Ethernet technology

Advances
in
Ethernet
Yaakov (J) Stein May 2011
Chief Scientist
RAD Data Communications

Outline
Modern Ethernet
VLANs and their uses
Ethernet services
Additional bridging functions
QoS Aspects
Link aggregation
Ethernet protection mechanisms
EFM
RPR
Ethernet OAM
Ethernet security
Synchronous Ethernet
AdvEth Slide 2

Modern Ethernet

Carrier grade Ethernet
IEEE 802 view
ITU-T view
MEF view
IETF view

AdvEth Slide 3

What is Ethernet anyway?
Ethernet has evolved far from its roots of half-duplex/CSMA/CD LANs
and is hard to pin down today

Metcalf’s original sketch of Ethernet
we may use the term today to describe
 full duplex 10G point-to-point optical links
 “Ethernet in the first mile” DSL access
 passive optical “GEPON” networks
 metro Ethernet networks
 “wireless Ethernet” 10M hot spots
 etc.

AdvEth Slide 4

“Carrier grade” Ethernet

Ethernet started out as a LAN technology
LAN networks are relatively small and operated by consumer
hence there are usually no management problems

as Ethernet technologies advances out of the LAN environment
new mechanisms are needed, e.g.
– OAM
– deterministic (Connection-Oriented) connections
– synchronization

the situation is further complicated by different “world views”
of various SDOs working on Ethernet standardization

AdvEth Slide 5

4 views

IEEE 802 LAN/MAN standards committee (since 1980)
Ethernet is a set of LAN/MAN standards

ITU-T (since 1865 / 1956)

Ethernet is several packet-based layer networks

Metro Ethernet Forum (since 2001)
Ethernet is a service provided to a customer

Internet Engineering Task Force (since 1986)
Ethernet is an IP-helper
AdvEth Slide 6

IEEE 802, misc WGs, documents
802 LAN/MAN Standards Committee
 802-2001
 802.1 LAN protocols WG
– 802.1D-2004 Note:
– 802.1Q-2005
– 802.1ad working groups and study groups
– 802.1ah (e.g 802.1, 802.3) are semi-permanent
 802.2 LLC
projects and task forces
 802.3 Ethernet WG
– 802.3-2005
(e.g. 802.3z, EFM) are temporary
– 802.3z GbE
– 802.3ad link aggregation project outputs are usually
– 802.3ah EFM absorbed into main WG document
– 802.3as 2000 byte frames
 802.11 Wireless LAN WG (WiFi)
– 802.11-2005
– 802.11a
– 802.11b
– 802.11g
 802.16 Broadband Wireless Access WG (WiMax)
 802.17 RPR WG
AdvEth Slide 7

802.3
actually, IEEE only calls 802.3 Ethernet

802.3 is a large standard, defining
 MAC frame format, including VLAN support
 medium specifications and attachment units (UTP, coax, fiber, PON)
 repeaters
 interfaces (e.g. MII, GMII)
 rate autonegotiation
 link aggregation (we will discuss later)
new projects continue to expand scope
 802.3aq 10GBASE-LRM
 802.3ar congestion management
 802.3as frame expansion

AdvEth Slide 8

MAC frame format
a MAC frame uses either of the following frame formats :

64 – 1518 B
DA (6B) SA (6B) T/L (2B) data (0-1500B) pad (0-46) FCS (4B)

68 – 1522 B
DA(6B) SA(6B) VT(2B) VLAN(2B) T/L(2B) data (0-1500B) pad(0-46) FCS(4B)
8100

802.3as expanded frame size to 2000B (approved September 2006)
Note: PHY frame may be larger – e.g. preamble, start-frame deliminator, etc.

AdvEth Slide 9

Ethernet Addressing

the most important part of any protocol’s overhead are the address fields

Ethernet has both source (SA) and destination (DA) fields
the addresses need to be unique to the network

the fields are 6-bytes in length in EUI-48 format
(once called MAC-48, EUI = Extended Unique Identifier)
248 = 281,474,976,710,656 possible addresses

addresses can be “universally administered” (burned in)
or “locally administered” (SW assigned)

AdvEth Slide 10

EUI-48 and EUI-64
EUI-48 used by
 Ethernet (802.3)
 Token ring (802.5)
 WiFi (802.11)
 Bluetooth
 FDDI
 SCSI/fiber-channel

IEEE defined a “next generation” 8-byte address called EUI-64
EUI-64 used for
 IEEE 1394 (firewire)
 802.15.4 (personal area networks)
 IPv6 (LSBs of non-temporary unicast address)

EUI addresses usually expressed in hex-hex format
Broadcast address is FF-FF-FF-FF-FF-FF
AdvEth Slide 11

EUI format
OUI1 OUI2 OUI3 EXT1 EXT2 EXT3

OUI 00-20-D2
X X X X X X U M is assigned to RAD

OUI (ex “company name”) is assigned by the IEEE Registration Authority
each OUI gives 16M addresses (IEEE expects not to run out before 2100)
the LSB of the OUI is the Multicast indicator (0=unicast, 1=multicast)
the next to LSB is the Universal / local bit
0 means UNIVERSALLY allocated address (all assigned OUIs have zero)
1 means there is no OUI - use any unique address
WARNING – bit is reversed in IPv6!
OUIs are also used by LLC SNAP and in slow protocols

AdvEth Slide 12

Ethernet clients
the 2-byte Ethertype identifies the client type
assigned by IEEE Registration Authority
all Ethertypes are greater than 0600 (1536 decimal)
some useful Ethertypes :
 0800 IPv4
 0806 ARP
 22F3 TRILL
 22F4 IS-IS
 8100 VLAN tag
 8138 Novell IPX
 814C SNMP over Ethernet
 86DD IPv6
 8809 slow protocols
 8847 MPLS unicast
 8848 MPLS multicast
 88D8 CESoETH
 88A8 Q-in-Q SVID / MAC-in-MAC BVID
 88F5 MVRP
 88F6 MMRP
 88F7 IEEE 1588v2
 8902 CFM OAM
see them all at http://standards.ieee.org/regauth/ethertype/eth.txt
get your own for only $2,500 ! (RAD has acquired 22E8 for bonding protocol)
AdvEth Slide 13

Slow protocol frames
slow protocols are slow – no more than 5 (or 10) frames per second
no more than 100 frames per link or ONU
slow protocol frames must be untagged, and must be padded if needed
slow protocols are for single links – they do not traverse bridges
there is a specific multicast address for multi-cast slow protocols
there can not be more than 10 slow protocols 01-80-C2-00-00-02

DA SA 8809 subtype …
802-3 Annex 43B
Subtype:
 1 is Link Aggregation Control Protocol (LACP)
 2 is link aggregation marker protocol
 3 is EFM OAM

AdvEth Slide 14

LLC
There are other ways to differentiate clients (other than by Ethertype)
 802.2 (Logical Link Control)

first three bytes of payload :
– Destination Service Access Point (1B)
– Source Service Access Point (1B)
– Control Field (1 or 2 B)

DA SA len LLC payload

Example SAPs 04 IBM SNA

06 IP

80 3Com

AA SNAP

BC Banyan

E0 Novel IPX/SPX

F4 FE CLNS

AdvEth Slide 15

SNAP
DA SA len LLC SNAP payload

 Sub-Network Access Protocol
LLC parameters plus expanded capabilities
SNAP can support IPX/SPX, TCP/IP, AppleTalk Phase 2, etc.
the first eight bytes of payload :
– Destination Service Access Point (1B) = 0xAA
– Source Service Access Point (1B) = 0xAA
– Control Field (1B) = 0x03
– OUI (3B)
– Type (2B) (if OUI=00:00:00 then EtherType)

 IPX (old Netware method, “raw”) - first 2B of payload FF:FF
– Note: standard DSAP/SSAP values can not be FF !
 RFC 1042 allows IPv4 over Ethernet with SNAP
– DSAP=AA, SSAP=AA, Control=3, SNAP=0 followed by Ethertype
AdvEth Slide 16

Parsing

if EtherType/Length > 1500 then EtherType

else if payload starts with FF-FF then Netware

else if payload starts with AA then SNAP

else LLC

DA SA len/Ethertype XX payload

AdvEth Slide 17

L2 control protocols
The IEEE (and others) have defined various control protocols (L2CPs)
Here are a few well-known L2CPs :
protocol DA reference
STP/RSTP/MSTP 01-80-C2-00-00-00 802.1D §8,9
802.2 LLC 802.1D§17 802.1Q §13
PAUSE 01-80-C2-00-00-01 802.3 §31B 802.3x
LACP/LAMP 01-80-C2-00-00-02 802.3 §43 (ex 802.3ad)
EtherType 88-09
Subtype 01 and 02
Link OAM 01-80-C2-00-00-02 802.3 §57 (ex 802.3ah)
EtherType 88-09
Subtype 03
ESMC 01-80-C2-00-00-02 G.8264
EtherType 88-09
Subtype 10
Port Authentication 01-80-C2-00-00-03 802.1X
E-LMI 01-80-C2-00-00-07 MEF-16
Provider MSTP 01-80-C2-00-00-08 802.1D § 802.1ad
Provider MMRP 01-80-C2-00-00-0D 802.1ak
LLDP 01-80-C2-00-00-0E 802.1AB-2009
EtherType 88-CC
GARP (GMRP, GVRP) Block 01-80-C2-00-00-20 802.1D §10, 11, 12
through 01-80-C2-00-00-2F

Note: we won’t discuss autonegotiation as it is a physical layer protocol (uses link pulses) AdvEth Slide 18

Ethernet over coax
IEEE notation: Rate-Modulation-CableLimits
 Rate in Mb/s
 Modulation can be BASEband, BROADband, PASSband
 CableLimits e.g. distance in units of 100m

 10BASE2
10 Mb/s thin coax (RG58) 185m CSMA/CD

 10BASE5
10 Mb/s thick coax (RG11) 500m CSMA/CD

 10BROAD36
10 Mb/s PSK CATV 2.8-3.6km CSMA/CD

AdvEth Slide 19

Ethernet over twisted pairs
 10BASE-T (T=Twisted pair)
10 Mb/s, Manchester, >100m, 2 pairs of UTP, CSMA/CD or FD
 100BASE-TX
“fast Ethernet”, 100Mb/s, 4B5B encoding, 2 pair CAT5, FD
 1000BASE-T
(ex 802.3ab, now 802.3 clause 40)
GbE, 4D-TCM-PAM5/EC, 100m, 4 pairs CAT5/5e/6, FD
 10PASS-TS
(ex EFM, now 802.3 clause 62), 10Mb/s, 750m DMT VDSL
 2BASE-TL
(ex EFM, now 802.3 clause 63), 2Mb/s, 2.7km, SHDSL

AdvEth Slide 20

Ethernet over optical fiber
 10BASE-FL
10 Mb/s, P2P, CSMA/CD / FD, 2km, backward-compatible with FOIRL
 100BASE-FX
100 Mb/s, multimode fiber, 4B5B, 400m HD / 2km FD
 1000BASE-LX
long (1270-1355 nm), 8B10B, >2km (single-mode), FD only
 1000BASE-SX
short- 850nm near IR , 8B10B, 220m (multi-mode), FD only
 10GBASE-SR/LR/ER/LX4
ex 802.3ae, short-range, long-range, extended range, WDM

AdvEth Slide 21

802.1D
802.1 discusses MAC bridges

802.1D is also a large standard, defining
 bridge operation (learning, aging, STP, etc.)
 the architectural model of a bridge
 bridge Protocol and BPDUs
 GARP management protocols
802.1Q is a separate document on VLAN operation

new projects continue to expand scope
 802.1ad – Q-in-Q
 802.1af – MAC key security
 802.1ag – OAM
 802.1ah – MAC-in-MAC
 802.1aj – 2-port MAC relay
 802.1au – congestion notification
AdvEth Slide 22

802.1 Baggy pants model

higher layer entities
(STP entity, bridge management, etc.)
frames
info
LLC LLC

MAC relay entity
MAC entity MAC entity

media media
dependent dependent
functions functions

port 1 port 2

Note: a bridge must have at least 2 ports
here we depict exactly 2 ports
AdvEth Slide 23

Baggy pants - forwarding


LLC LLC

MAC relay entity

receive transmit
frame frame

port 1 port 2

Note: relay entity passes frame to port 2
dependent on port state and filtering database
AdvEth Slide 24

Baggy pants - learning


LLC LLC
port
state learning
filtering DB
receive transmit
frame frame

port 1 port 2

Note: we do not show forwarding of packet that may occur
AdvEth Slide 25

Baggy pants - STP
bridge
protocol
entity

LLC LLC
port port
state state
filtering DB

RCV XMT XMT RCV

port 1 port 2

Note: PDUs are sent and received by the bridge protocol entity
bridge protocol entity updates filtering DB and port states
AdvEth Slide 26

Translation to G.805
we can redraw the baggy pants model per G.805
(from G.8010 Appendix II) Note: drawn for CO case only

ETH/BP ETH/BP

ETH ETH
ETH

ETY/ETH ETY/ETH

ETY ETY

AdvEth Slide 27

Extension to N ports

higher layer entities in the baggy pants diagram
port 1 and port 2 are identical
so it is enough to draw once
LLC if there are many ports
the relay entity becomes
MAC relay entity an internal LAN !
MAC entity

media
dependent
functions

port 1
MAC
entity
MAC … MAC
entity entity

port 1 port 2 port N AdvEth Slide 28

ITU-T view
the name Ethernet disguises many different layer networks

ETH (MAC layer) is a packet/frame CO/CL network
there is also a VLAN variant called ETH-m
ETH can run over various server layers, including ETY

ETY (PHY layer) has a number of options
ETYn n = 1, 2.1, 2.2, 3.1, 3.2, 3.3, 4
 ETY1 : 10BASE-T (twisted pair electrical; full-duplex only)
 ETY2.1: 100BASE-TX (twisted pair electrical; full-duplex only; for further study)
 ETY2.2: 100BASE-FX (optical; full-duplex only; for further study)
 ETY3.1: 1000BASE-T (copper; for further study)
 ETY3.2: 1000BASE-LX/SX (long- and short-haul optical; full duplex only)
 ETY3.3: 1000BASE-CX (short-haul copper; full duplex only; for further study)
 ETY4 : 10GBASE-S/L/E (optical; for further study)

AdvEth Slide 29

ITU-T Recommendations

G.8001 – EoT definitions
G.8010 – Ethernet layer network architecture
G.8011 – Ethernet over Transport services framework
G.8011.1 – Ethernet private line service
G.8011.2 – Ethernet virtual private line service
G.8012 – Ethernet UNI and NNI
G.8021 – Ethernet transport equipment characteristics
G.8031 – Ethernet linear protection switching
G.8032 – Ethernet ring protection switching
Y.1730 – Ethernet OAM - requirements
Y.1731 – Ethernet OAM

AdvEth Slide 30

Ethernet servers

Ethernet can be carried over
 coaxial cable
ETYn  twisted copper pairs
 optical fibers

 synchronous (TDM) networks

 packet switched networks (PSN)

AdvEth Slide 31

Ethernet over TDM

over SONET/SDH (see EoS course)
 PoS (PPP/HDLC)
 LAPS
 GFP

over low-rate TDM
 PPP/HDLC
 GFP

over OTN
 GFP

AdvEth Slide 32

Ethernet over PSN

IP (EtherIP RFC 3378)

MPLS
Ethernet PW (RFC 4448, Y.1415)
see PWE3 course
L2VPN services (VPWS/VPLS)
see VPLS course

Ethernet (MAC-in-MAC 802.1ah)

ATM (LAN emulation)

AdvEth Slide 33

ETH layer network
ETH is a packet/frame-based layer network
it maintains client/server relationships with other networks
networks that use Ethernet are Ethernet clients
networks that Ethernet uses are Ethernet servers
sometimes Ethernet ETY is the lowest server
i.e. there is no lower layer server network
ETH is usually connectionless
but connection-oriented variants have been proposed (PBT, PVT, etc)
ETH is a relatively simple layer network
it has no real forwarding operations
just filtering and topology pruning
it has no real control plane
just STP, GARP, “slow protocol frames”, etc.
until recently it had no OAM
but now there are two
AdvEth Slide 34

ETH adaptations
ETH_TFP ETH_FP ETH_TFP ETH_FP s

SRV/ETH SRV/ETH-m

SRV_AP SRV_AP

the adaptation from ETH to the server layer (e.g. ETY) has
 1 ETH Termination Flow Point responsible for DA, SA, P bits, OAM
 1 (for ETH-m between 1 and 4094) ETH Flow Point(s)
where the ETH CI enters
 1 SRV Access Point (SRV can be ETY, but can be other server networks)

AdvEth Slide 35

Traffic conditioning

ETH_FP
G.8010 defines a new function (not in G.805/G.809)
traffic conditioning function:
 inputs CI
ETH
 classifies traffic units according to configured rules
 meters traffic units within class to determine eligibility
 polices non-conformant traffic units ETH_FP

 outputs remaining traffic units as CI

technically, the TC function is placed by expanding the ETH Flow Point

AdvEth Slide 36

MEF view
MEF focuses on Ethernet as a service to a customer
the service is provided by a Metro Ethernet Network (any technology / architecture)
the service is seen by the Customer Edge
the UNI is the demarcation point between customer and MEN
each UNI serves a single customer, presents a standard Ethernet interface
at the UNI CE and MEN exchanged service (MAC) frames
connection between UNIs called an Ethernet Virtual Connection

UNI UNI
CE CE
MEN
ingress
egress

AdvEth Slide 37

MEF Technical Specifications (1)
MEF 1 Ethernet Services Model - Phase 1 (obsoleted by MEF 10)
MEF 2 Requirements and Framework for Ethernet Service Protection
MEF 3 Circuit Emulation Requirements
MEF 4 MEN Architecture Framework Part 1: Generic Framework
MEF 5 Traffic Management Specification – Phase 1 (obsoleted by MEF 10)
MEF 6.1 Metro Ethernet Services Definitions (Phase 2)
MEF 7.1 EMS-NMS Information Model (Phase 2)
MEF 8 PDH over MEN Implementation Agreement (CESoETH)
MEF 9 Abstract Test Suite for Ethernet Services at the UNI
MEF 10.2 Ethernet Services Attributes (Phase 2)
MEF 10.2.1 Performance Attributes Amendment to MEF10.2
MEF 11 User Network Interface (UNI) Requirements and Framework
MEF 12 MAN Architecture Framework Part 2: Ethernet Services Layer
MEF 12.1 MAN Architecture Framework Part 2: Ethernet Services Layer Basic Elements
MEF 13 User Network Interface (UNI) Type 1 Implementation Agreement
MEF 14 Abstract Test Suite for Ethernet Services at the UNI
MEF 15 MEN Management Requirements - Phase 1 Network Elements
MEF 16 Ethernet Local Management Interface
MEF 17 Service OAM Framework and Requirements
MEF 18 Abstract Test Suite for Circuit Emulation Services
MEF 19 Abstract Test Suite for UNI Type 1
MEF 20 UNI Type 2 Implementation Agreement

AdvEth Slide 38

MEF Technical Specifications (1)
MEF 21 Abstract Test Suite for UNI Type 2 Part 1 Link OAM
MEF 22 Mobile Backhaul Implementation Agreement
MEF 23 Class of Service Phase 1 Implementation Agreement
MEF 24 Abstract Test Suite for UNI Type 2 Part 2 E-LMI
MEF 25 Abstract Test Suite for UNI Type 2 Part 3 Service OAM
MEF 26 External Network Network Interface - ENNI (Phase 1)
MEF 26.0.1 Amendment to MEF-26 – The Bandwidth Profile Algorithm
MEF 26.0.2 OVC Layer 2 Control Protocol Tunneling Amendment to MEF 26
MEF 27 Abstract Test Suite for UNI Type 2 Part 5: Enhanced UNI and Part 6: L2CP Handling
MEF 28 ENNI Support for UNI Tunnel Access and Virtual UNI
MEF 29 Ethernet Service Constructs
MEF 30 Service OAM FM IA
MEF 31 Service OAM FM MIB

AdvEth Slide 39

Other reference points
the UNI stands between the CE and MEN
the processing functions needed at the CE to connect to the MEN
are called UNI-C
the processing functions needed at the MEN to connect to the CE
are called UNI-N

between networks elements of a MEN we have I-NNI interfaces
while between different MENs we have E-NNI interfaces
(MEF 4 also defines NI-NNI, SI-NNI and SNI interfaces)

CE
UNI I-NNI E-NNI
UNI-C UNI-N MEN-y
MEN-x
AdvEth Slide 40

EVCs
a public MEN can not behave like a shared LAN
since ingress frames must not be delivered to incorrect customers
an association of 2 or more UNIs is called an EVC
ingress frames must be delivered only to UNI(s) in the same EVC
when several UNIs frames may be flooded to all or selectively forwarded
frames with FCS errors must be dropped in the MEN (to avoid incorrect delivery)
a single UNI may belong to several EVCs (differentiated by port and/or VLAN ID)

EVC 1 EVC 2
HQ
EVCs 1, 2, 3
MEN

EVC 3

AdvEth Slide 41

EVC types
a point-to-point EVC associates exactly 2 UNIs
 the service provided is called E-LINE [MEF-6] UNI UNI
MEN
a multipoint-to-multipoint EVC connects 2 or more UNIs

Note: MP2MP w/ 2 UNIs is different from P2P (new UNIs can be added)
unicast frames may flooded or selectively forwarded
broadcast/multicast frames are replicated and sent to all UNIs in the EVC
 the service provided is called E-LAN [MEF-6]

UNI
a tree-topology EVC connects one UNI to many UNIs
 the service provided is called E-TREE UNI UNI
MEN
we will see more details on Ethernet services later UNI

AdvEth Slide 42

New MEF Model (12.1)
MEF is updating their architecture model
 Metro  Carrier so MEN  CEN
 EVC is no longer a transport entity
 Ethernet Connection (EC) is the entity that connects
Ethernet flow termination points
 ECs traversing several CENs are composed of EC segments (ECS)
 Operator Virtual Connections (OVCs) connect ENNIs
with other ENNIs or UNIs
ENNI-N ENNI-N UNI-N UNI-C
UNI-C UNI-N

UNI ENNI UNI
Subscriber
Subscriber CEN 1 CEN 2 B
A

EVC
S-EC
S-ECSs
OVCs
SP-EC
O-ECSs AdvEth Slide 43

What about the IETF?
Ethernet is often used to carry IP packets
since IP does not define lower layers
since IP only forwards up to the LAN, not to the endpoint

both IP and Ethernet use addresses
but these addresses are not compatible (exception – IPv6 local address)

the Address Resolution Protocol (RFC 826 / STD 37) solves this problem
if you need to know the MAC address that corresponds to an IP address
– broadcast an ARP request (Ethertype 0806, address FF…FF)
– all hosts on LAN receive
– host with given IP address unicasts back an “ARP reply”

AdvEth Slide 44

Other ARP-like protocols
other related protocols (some use the ARP packet format)
 GARP (gratuitous ARP – WARNING not 802.1 GARP)
host sends its MAC-IP binding without request (e.g. backup server)
 Proxy ARP
router responds to ARP request to capture frames
 Reverse ARP, BOOTP, DHCP
host sends its MAC and wants to know its IP address
 Inverse ARP
frame-relay station unicasts DLCI to find out remote IP address
 ARP mediation
mediate over L2VPN between networks using different ARPs
(e.g. Ethernet on one side and FR on the other)

AdvEth Slide 45

VLANs

VLANs
tagging (802.1Q)
SVL and IVL switches
VLAN stacking
PBN and PBBN
PBT
MPLS-TP

AdvEth Slide 46

Virtual LANs
in standard practice each LAN needs its own infrastructure
 1 broadcast domain per set of cables and hubs
 all stations on LAN see all traffic

we may want a single physical infrastructure to support many LANs
 simpler and less expensive than maintaining separate infrastructures
 multiple low-speed LANs on one high-speed infrastructure
 segment broadcast domains (lower BW/processing) without routers
 security for different departments in company / groups in campus

separation may be based on switch ports or MAC address or VLAN ID (tag)

we will not delve deeply into VLANs here (see e.g. 802.1Q Appendix D)
I assume that this is treated in elementary Ethernet course

port-based
VLAN

AdvEth Slide 47

Virtual LANs (cont.)
initially there were proprietary solutions to tagging

802.1Q & 802.1p projects defined format, protocols, and procedures
 802.1p results were incorporated into 802.1D-1998
– priority
 802.1Q intentionally left separate and NOT incorporated
considered sufficiently distinct from non-VLAN bridging
– in particular, baggy pants model enhanced
– new protocol – GVRP (see below)

802.1ad and 802.1ah further extend tagging formats and procedures

VID VLAN

AdvEth Slide 48

VLAN ID (VID)
2B VLAN tag

P-bits(3b) CFI(1b) VID(12b)
Canonical Format Indicator

802.1Q mandates 12 bit VID (carried after Ethertype 8100)
 2 bytes carry P (priority) bits, CFI (not important here, always 0) and VID
 4094 possible VID values (0 and 4095 are reserved)
 VID=0 frames are priority tagged, able to carry P bits

VLAN-aware switches
 take VID into account when forwarding
 perform VID insertion/removal
 never output a priority-tagged frame

when VLAN-aware switch receives
 VLAN tagged frame – treats according to VID
 untagged frame – may push permanent VID (PVID) of receive port
 priority-tagged frame treated like untagged frame (VLAN tag MAY be added)

Insertion / removal of VLAN tag necessitates recomputing FCS and adjusting padding
AdvEth Slide 49

VLAN switch operation
A VLAN-aware switch performs 5-stage processing:
 ingress rule checking
– 2 modes: admit only tagged, admit all
– classify every incoming frame to a VID (if untagged to PVID)
– discard frame not obeying rules, e.g.
 port not in VID member set

 untagged with admit only tagged

 active topology enforcement
– check that frame should be forwarded, discard if, e.g.
 spanning tree forbids forwarding or forwarding is back to port of origin

 port not in forwarding state

 MTU exceeded

 frame filtering (according to MAC, VID and filtering DB entry)
 egress rule checking
– discard if VID not in member set
– add/remove tag as needed
 queuing for transmission

AdvEth Slide 50

SVL (SFD) switches
MAC address PORT
Shared VLAN Learning

(Single Forwarding Database)

how do VIDs interact with 802.1D (forwarding and learning) ?
there are two different answers to this question
SVL switches still maintain a single 802.1D filtering database
but use VLAN in ingress/egress classification

MAC addresses are learnt together for all VLANs (flood MAC once)
path to MAC does not depend on VID
a MAC address belongs to at most 1 VLAN
asymmetry possible
AdvEth Slide 51

Asymmetry case
1

3
2

green PC can talk to server
 untagged frames on port 1 are tagged with VID=1
 tags removed when sent to server

red PC can talk to server
 untagged frames on port 2 are tagged with VID=2
 tags removed when sent to server

server can reply to both
 untagged frames are tagged with VID=3
 tags removed when sent out of ports 1 or 2

but green and red PCs can NOT talk to each other
 VID=1 traffic can not be sent to red PC with MAC associated with VID=2
 VID=2 traffic can not be sent to green PC with MAC associated with VID=1

AdvEth Slide 52

IVL (MFD) switches
MAC address PORT VID=1
Independent VLAN Learning
(Multiple Forwarding Databases)
MAC address PORT …

IVL switches maintain separate 802.1D filtering databases per VID
MAC addresses are learnt independently for each VID (more flooding)
1 MAC address can belong to several VLANs
 but path to MAC depends on VID
asymmetry impossible
Note: IVL switch can be implemented as 60 (48+12) bit lookup
AdvEth Slide 53

VLAN stacking

we tag Ethernet frames by using Ethertype 8100
DA SA 8100 VLAN 1 type data pad FCS

first Ethertype is set to 8100
second Ethertype is payload protocol (as in untagged frame)
but what if we add another Ethertype to 8100 ?

DA SA 8100 VLAN 2 8100 VLAN 1 type data pad FCS

this is called VLAN stacking
Warning:
or (for obvious reasons) Q-in-Q
although superficially Q-in-Q
stacking is not mentioned in 802.1Q looks like an MPLS stack,
but not ruled out either! there is no network layering here –
the DA remains the same!
AdvEth Slide 54

Provider Bridges – 802.1ad
why stack VLANs? CE PE PBN PE CE
1 reason is for Provider Bridge Networks
customers may use VIDs for internal reasons
and will want them maintained across the PBN
802.1ad
but what if multiple customers use the same VIDs ?
approved Dec 2005
the provider must either: published May 2006
 manage customer VIDs
– allocate ranges to customers
– swap at ingress and egress or
 treat them as Customer VIDs, and push a Service VID (customer ID)

CVID=1…100
CE SVID=1…2 CE
CVID=1…100 PE PE
CE CE
AdvEth Slide 55

CVID and SVID
customer frames have C-TAGs, may only have priority S-TAGs
PBN frames have S-TAGs and usually have C-TAGs
 C-TAG contains a C-VID
 S-TAG contains an S-VID

C-TAGs are standard format VLAN tags
802.1ad S-TAGs are similar, but use Ethertype 88A8
since they have Drop Eligible Indicator instead of CFI
service transparency
 PE inserts S-TAG, C-TAG becomes invisible to PBN
 PE removes S-TAG, C-TAG becomes visible to customer network

D
88A8 (S-TAG) P E S-VID
I
C
8100 (C-TAG) P F C-VID
I
AdvEth Slide 56

Problems with PBNs

Q-in-Q PBNs simplify provider-customer interface, but
 are limited to 4K SVIDs, i.e. 4K customers
(VLANs derive from enterprise (not carrier) applications)
 do not provide true client/server (decoupled) relationship
– customer VIDs are hidden
but not customer MAC addresses
– no true OAM trace functionality
 provider switches still have to learn customer MAC addresses
we would really like full decoupling, i.e. a client/server relationship
this can be done via MAC-in-MAC

AdvEth Slide 57

Progress to MAC-in-MAC
802.1D
DA SA T payload FCS

802.1Q
DA SA 8100 VLAN T payload FCS

802.1ad
DA SA 88A8 S-TAG 8100 C-TAG T payload FCS

802.1ah
B-DA B-SA 88A8 B-TAG TBD I-TAG …
DA SA 88A8 S-TAG 8100 C-TAG T payload FCS

AdvEth Slide 58

802.1ah
PBBN 802.1ah CE
approved – June 2008 CE 802.1ad interface CE
CE PE PBN
802.1D or 802.1Q interface BE CE
BE PBBN
CE PBN PE
CE
B B BE
CE
802.1ah interface PE
Provider Backbone Bridge Networks PBN
backbone provider is a “carrier’s carrier”
Backbone Edge switches use CE
CE CE
 I-TAGs with I-SID
 B-TAG with B-VID
 one or more I-TAGs and a B-TAG

I-TAG is a new format, I-SID is a 24-bit label (no more 4K limitation)

4B I-TAG
I-P(3b) I-DEI(1b) RES(4b) ISID (24b)
AdvEth Slide 59

PBT (PBB-TE) 802.1Qay
Provider Backbone Transport builds on 802.1ah PBBNs
to achieves reliable, deterministic, carrier-class behavior
802.1ah gives backbone provider its own addressing space (MAC + VLAN)
addresses not shared with customer (no need to learn customer MACs)
and so provider is free to use address space as it sees fit

we saw before that IVL switches forward based on 60-bit addresses
but their capabilities limited due to limitations of STP, flooding, etc

but most IVL switches allow static FID (preconfigured forwarding behavior)
and support turning off learning/STP/flooding/aging BVID=1
we can thus set up pure connection-oriented topology

we can use management (OSS) BVID=2
or control plane protocols (e.g. RSVP-TE) to populate FID tables
(IETF GELS/CCAMP, ITU G.pbt)

AdvEth Slide 60

What about MPLS ?

another way of carrying customer Ethernet frames over a provider network
is to use MPLS (Ethernet PW, VPWS, VPLS)
(see MPLS, PWE and VPLS courses)
also complete decouples customer and provider networks
furthermore, MPLS is carrier-class (deterministic, CO, OAM, etc.)
and widely deployed (for IP and L3VPN applications)
MPLS can be carried over carrier SONET/SDH networks

MPLS label PW label CW DA SA 8100 C-TAG T payload FCS

AdvEth Slide 61

PBT vs. MPLS

 both achieve complete client/server decoupling
 PBT exploits existing IVL switches
– but many switches today can do MPLS forwarding
 Ethernet frame has SA, so OAM traceback easy
– MPLS swaps labels and contains only destination semantics
so need OAM for CV and mismerge detection
 PBT can co-exist with bridged Ethernet
 MPLS has highly developed control plane
– Ethernet presently requires manual configuration
– can use OSS, but not standardized
– may be able to use GMPLS control plane (GELS)
 MPLS can transport non-Ethernet clients (IP, PWs)

AdvEth Slide 62

More alternatives
there are other ways to
 set up CO connections
 avoid use of customer MAC addresses

MPLS-TP (Transport Profile)
 add an MPLS label to the ETH overhead
 in provider network switch solely based on label

similar to regular MPLS, but
 performed by switch instead of LSR
 various transport extensions such as linear/ring protection, OAM

TRILL (Transparent Interconnection of Lots of Links ) - see later on
 invented by Radia Perlman (inventor of STP and IS-IS)
 uses IS-IS directly on MAC addresses (no need to configure IP addresses)
 adds outer MAC header + shim header (with TTL)
 is completely "no-touch" (plug-and-play).
 finds optimal paths
AdvEth Slide 63

Ethernet services

EVCs and bundling
Ethernet Private Line (EPL)
Ethernet Virtual Private Line (EVPL)
Ethernet Private LAN (EPLAN)
Ethernet Virtual Private LAN (EVPLAN)

AdvEth Slide 64

Ethernet services
we previously defined
 E-LINE point-to-point layer 2 service
 E-LAN multipoint-to-multipoint Ethernet service

but MEF and ITU have gone a step further

MEF 6 splits E-LINE into EPL and EVPL
ITU followed - Recommendations: G.8011.1 and G.8011.2
and E-LAN can be split into EPLAN and EVPLAN

these distinctions are made in order to live up to SLAs
i.e. provide defined service attributes

AdvEth Slide 65

EVCs revisited
in our previous discussion of EVCs we didn’t mention VLANs
we now realize customer EVCs can be distinguished by VLAN IDs

if the transport infrastructure is ETH, there may be an SVID
if the customer wants to have several EVCs, there will be a CVID
(here we simply mean the customer’s 802.1Q VLAN ID)

the provider may promise “VLAN preservation”
i.e. not change CVIDs (untagged remain untagged)

at the UNI-N there will be a CVID to EVC map (see MEF 10.1)
there can be three types of maps:
 all to one
 one to one (not MEF 10 term)
 arbitrary (not MEF 10 term)

AdvEth Slide 66

All to one bundling map
 all frames (independent of CVID) are mapped to the same EVC
 VLAN preservation
 no need for customer-provider coordination
 when p2p: similar to leased line
 when mp2mp: similar to TLS
 support multiple customer EVCs by different switch ports
 can’t mix all to one switch with other map types in single EVC

all CVIDs all to one
1 EVC 1 150
arbitrary
2 EVC 2 1 .. 100
150
101 .. 200
all CVIDs
wrong switch gets response
AdvEth Slide 67

One to one bundling map

 each CVID mapped to a different EVC
 untagged (and priority tagged) mapped to default EVC
 support multiple EVCs from a single switch port
 no VLAN preservation can makes customer configuration easier
 similar to frame relay (DLCI identifies PVC)

C
CVID=1001
CVID=1
CVID=1
EVC 1
CVID=1002
CVID=2 SP CVID=1
C
EVC 2

default EVC CVID=1003 CVID=1
untagged
C
AdvEth Slide 68

Arbitrary bundling map
 multiple CVIDs per EVC
 but multiple EVCs per port
 VLAN preservation
 can ensure customer traffic only goes to sites where VLAN is needed
 more efficient BW use
 need customer and SP coordination as to CVID – EVC map
 can coexist with one to one switches on same EVC

CVID=1 … 100 EVC 1
CVID=101 … 200
EVC 2

untagged default EVC

AdvEth Slide 69

EPL
Ethernet Private Line is a dedicated-BW E-LINE (p2p) service
transport network seems to be a transparent cable
no frame loss unless FCS errors
CE PE SP PE CE
transport layer may be
 native Ethernet – dedicated to single EVC (e.g. 100 Mb/s)
 TDM or SONET/SDH timeslot (e.g. X.86, GFP)
 VPWS service in TE tunnel

ITU further divides EPL into
 type 1 – terminate ETY, transport MAC frame over server (SDH/GFP-F, MPLS)
 type 2 – transparent transport (e.g. GFP-T)
 native (special case for 10GBASE-W)

AdvEth Slide 70

EVPL
Ethernet Virtual Private Line is a shared-BW E-LINE (p2p) service
statistical multiplexing of user traffic, marked by VLAN IDs
(actually, all resources are shared – constraint may be switch fabric computation)
there may be frame loss due to congestion
normally a policing function is required at SP network ingress

CE CE
EPL CE
PE PE
CE ITU terms:
spatial vs. logical
traffic separation
CE CE
EVPL PE PE
CE CE
AdvEth Slide 71

EPLAN
Ethernet Private LAN is a dedicated-BW E-LAN service
possible SP topologies
 full mesh CE PE PE CE
 star
 main switch PE

CE PE PE CE CE
P

PE

CE PE PE CE CE

PE

CE

AdvEth Slide 72

EVPLAN
Ethernet Virtual Private LAN is a shared-BW E-LAN service
statmuxed BW and switch fabric are shared among customers
useful service, but most difficult to manage (not yet studied)
when server is MPLS, this is VPLS
best effort version is widely deployed

CE
CE PE PE CE
CE CE
PE

CE CE CE

AdvEth Slide 73

Additional bridging functions

GARP, GVRP, GMRP (802.1ak)
rapid spanning tree (802.1w)
multiple spanning trees (802.1s-2002)
Rbridges

AdvEth Slide 74

GARP (802.1D clause 12)

Generic Attribute Registration Protocol (WARNING not Gratuitous ARP)
generic framework to declare, withdraw, register and remove attributes
GARP defines architecture, protocol, state machine
Example uses:
– VLAN IDs (GVRP)
– multicast group membership (GMRP)

PID MSG1 MSG2 … MSGn END

TYPE ATTR1 ATTR2 … ATTRn END

LEN EVENT VALUE GARP PDU
AdvEth Slide 75

GVRP (802.1Q clause 11)
GARP VLAN Registration Protocol performs automatic VLAN configuration
to properly process VLAN tagged frames, the VLAN switches need to know
 the VLANs in which it participates
 which ports to use for VLAN members
VLAN configuration of all switches needs to be consistent
802.1Q allows:
 static provisioning of VLAN membership information
(via management mechanisms)
 dynamic configuration and distribution of VLAN membership info

to add a new switch to a VLAN:
 with static provisioning need to configure every switch
 with GVRP need to configure only one switch
GVRP then sends out info needed to configure all the other switches

AdvEth Slide 76

GMRP (802.1D clause 10)

GARP Multicast Registration Protocol distributes multicast group info

frames with multicast address
need to be replicated and sent to all members of the multicast group

GMRP enables automatic registering and deregistering
FIDs ensure that multicast frames are only sent to bridges that need them
GMRP must find a sub-tree of the spanning tree

AdvEth Slide 77

RSTP (802.1w)
Rapid Spanning Tree Protocol (AKA rapid reconfiguration)
RSTP configures the state of each switch port
in order to eliminate loops
STP may takes minutes to (re)converge
goal of RSTP is 10 ms. convergence
RSTP is an evolutionary update of STP 802.1w incorporated into
new algorithm 802.1D-2004 clause 17
same terminology it supersedes the previous
mostly same parameters STP and STA
backwards compatible with STP
but
additions to BPDU format (all 8 bits of flag byte used)
simplified port states
new variable holding the port role

AdvEth Slide 78

RSTP states and roles
The 802.1D concept of port state includes both
 forwarding state (blocks or forwards traffic) and
 topology role (root port, designated port).

802.1w decouples the concepts
802.1D has 5 port states 802.1w has only 3
disabled
blocking discarding
listening
learning learning
forwarding forwarding
802.1D defines a concept of port role, but has no matching variable
Spanning Tree Algorithm determines role based on BPDUs
802.1w defines 4 port roles
 root
 designated
 backup
 alternate

AdvEth Slide 79

multiple spanning trees 802.1s
conventionally, all VLANs use the same spanning tree
(even if IVL switches use different FIDs)
so links blocked by STP will never carry any traffic

we can utilize these links
if different VLANs could use different spanning trees

Multiple Spanning Tree Protocol - 1998 amendment to 802.1Q
the protocol and algorithm are now in 802.1Q-2003 clauses 13 and 14

MSTP configures a separate spanning tree for each VLAN
blocks redundant links separately for each spanning tree

Cisco has its own Per VLAN Spanning Tree (PVST and PVST+) protocols

AdvEth Slide 80

Rbridges (IETF TRILL WG)

Spanning tree is a clean protocol - needs no configuration
but STP converges slowly
and may make inefficient trees
hosts that are actually close become far apart
we could use IP routing protocols
but that requires allocating IP addresses, etc.

A new solution TRansparent Interconnection of Lots of Links
defines a combination of router and bridge called an Rbridge
that run a link state protocol (e.g. OSPF, IS-IS)

Rbridges have the advantages of both with the disadvantages of neither
 optimized paths
 but no configuration
 no IP layer
AdvEth Slide 81

Algorhyme
I think that I shall never see
a graph more lovely than a tree.
A tree whose crucial property
is loop-free connectivity.
A tree that must be sure to span
so packet can reach every LAN.
First, the root must be selected.
by ID, it is elected.
Least-cost paths from root are traced.
in the tree, these paths are placed.
A mesh is made by folks like me,
then bridges find a spanning tree.

Radia Perlman

AdvEth Slide 82

Algorhyme v2
I hope that we shall one day see
a graph more lovely than a tree.
A graph to boost efficiency
while still configuration-free.
A network where RBridges can
route packets to their target LAN.
The paths they find, to our elation,
are least cost paths to destination.
With packet hop counts we now see,
the network need not be loop-free.
RBridges work transparently.
without a common spanning tree.
Ray Perlner

AdvEth Slide 83

QoS Aspects

Flow control (PAUSE frames)
handling QoS
prioritization (802.1p)
MEF service attributes

AdvEth Slide 84

Flow control
When an Ethernet switch receives traffic faster than it can process it
it needs to tell its immediate neighbor(s) to slow down

On half-duplex links the back pressure can be employed
 overloaded device jams the shared media by sending preambles or idle frames

 detected by other devices as collisions causing senders to wait (CSMA/CD)

On full-duplex point-to-point links, PAUSE frames are sent
Since they are sent on a point-to-point link, the DA is unimportant,
and the standard multicast address 01-80-C2-00-00-01 is used
making the PAUSE frame easy to recognize

The PAUSE frame encodes the requested pause period
as a 2-byte unsigned integer representing units of 512 bit times

AdvEth Slide 85

Handling QoS

output port 3
output port 1

output port 2
Ethernet switches have FIFO buffers
on each port's input and output
But prioritization may be needed
so output buffers may be divided into multiple queues
outgoing frames put into queues of specified priority switch switch
fabric fabric
we could base priority on input port
but then for the next switch to know the priority too

input port 2
input port 1

input port 3
we would need to send to its appropriate port too
so the number of both input and output ports
would be multiplied by the number of priority levels!

a better way is to mark the frames

AdvEth Slide 86

802.1p
the VLAN tag reserves a 3 bit user priority field AKA P-bits
P-bits allow marking individual frames with a value 0 … 7
non-VLAN frames can use priority tagging (VLAN=0)
just to have a user priority field

user priority levels map to traffic classes (CoS)
traffic class indicates drop probability, latency across the switch, etc.
but there are no BW/latency/jitter guarantees

P=0 means non-expedited traffic
802.1Q recommends mappings from P-bits to traffic class

see later for RPR traffic classes and priority

AdvEth Slide 87

(MEF) Service attributes
all per EVC, per CoS
 frame loss
fraction of frames that should be delivered that actually are delivered
specified by T (time interval) and L (loss objective)

 frame delay
measured UNI-N to UNI-N on delivered frames
specified by T, P (percentage) and D (delay objective)

 frame delay variation
specified by T, P, L (difference in arrival times), V (FDV objective)

 BW profiles
per EVC, per CoS, per UNI
specified by CIR, CBS, EIR, EBS, …

AdvEth Slide 88

Burst size token buckets
the profile is enforced in the following way
there are two byte buckets, C of size CBS and E of size EBS
tokens are added to the buckets at rate CIR/8 and EIR/8
when bucket overflows tokens are lost (use it or lose it)

if ingress frame length < number of tokens in C bucket
frame is green and its length in tokens is debited from C bucket
else if ingress frame length < number of tokens in E bucket
frame is yellow and its length of tokens is debited from E bucket
else frame is red
CBS
EBS
green frames are delivered and service objectives apply
yellow frames are delivered by service objectives don’t apply
red frames are discarded C E

AdvEth Slide 89

Hierarchical BW profiles
MEF 10.1 allows bandwidth profile
 per UNI (can be different at different UNIs of same multipoint EVC)
 per EVC and CoS
but doesn’t allow a single frame to be subject to more than 1 profile
New work in the MEF is aimed at allowing
 per CoS bandwidth profile, followed by
 per EVC color-aware profile

The idea is to allow the user to use excess “paid for” bandwidth
for lower priority traffic (BW sharing)
Thus
 frames will never be downgraded

sharing
(greenyellow, or yellowred) coupling

 frames may be upgraded
(redyellow, yellowgreen)
There are complex inter-relationships
between sharing and coupling
AdvEth Slide 90

Link aggregation

Link aggregation (ex 802.3ad, 802.3 clause 43)
Link Aggregation Control Protocol (LACP)
conversations

AdvEth Slide 91

Link Aggregation task force
Ethernet needed “link aggregation”
(AKA bonding, Ethernet trunk, inverse mux, NIC teaming, etc)

enables bonding several ports together as single uplink
 increased uplink BW can exceed 1 Gb/s (or now 10Gb/s)
 common practice to install multiple fibers/cables
 incrementally grow uplink capacity
– needn’t purchase new expensive Gb switch when exceed 100 Mb
 increased availability continue at reduced rate when 1 link fails
 needn’t constrain peak capacity of individual ports

Link Aggregation 802.3ad task force
PAR approved June 1998
WG ballot Nov 1999
LMSC ballot Nov 1999
standard Feb 2000
folded into 802.3-2000 as clause 43

Alternative inverse MUX defined by EFM task force (EFM bonding)
AdvEth Slide 92

Link aggregation in action
Link Aggregation Group controlled by aggregator
aggregation port looks standard Ethernet MAC (no SN, etc.)
MAC address may be one that of one of the links
only for p2p full duplex operation
the aggregator = frame distributor + frame collector + parser + multiplexer
 distributes frames to links making up LAG
 collects frames from LAG and passes to clients

link aggregation should not cause misordering, replication, etc.
binding of ports to LAGs distributed via Link Aggregation Control Protocol
LACP uses slow protocol frames
links may be dynamically added/removed from LAG
optional marker protocol provides sequence markers

AdvEth Slide 93

LA conversations
frame distributor assigns all frames from a conversation to one link
a conversation is defined as frames with same:
 SA
 DA
 reception port
 protocol (Ethertype)
 higher layer protocol (LC info)

hash on above maps to port
before moving conversation to a different link,
ensure that all transmitted frames have been received (marker protocol)

LACP continuously monitors to detect if changes needed

AdvEth Slide 94

Ethernet protection

Linear protection
Ring protection

Y(J)S APS Slide 95

APS
Automatic Protection Switching (APS)
is a functionality of carrier-grade transport networks
is often called resilience
since it enables service to quickly recover from failures
is required to ensure high reliability and availability

APS includes :
 detection of failures (signal fail or signal degrade) on a working channel
 switching traffic transmission to a protection channel
 selecting traffic reception from the protection channel
 (optionally) reverting back to the working channel once failure is repaired

Y(J)S APS Slide 96

Using STP and LAG
STP and RSTP automatically converge to a loop-free topology
RSTP converges in about the same time as STP
but can reconverge after a topology change in less than 1 second
Thus RSTP can be used as a protection mechanism
However, the switching time will be many tens of ms to 100s of ms

LAG also detects failures (using physical layer or LACP)
and automatically removes failed links
Thus LAG too can be used as a primitive protection mechanism
When used this way it is called worker/standby or N+N mode
The restoration time will be on the order of 1 second

Y(J)S APS Slide 97

G.8031
Q9 of SG15 in the ITU-T is responsible for protection switching
In 2006 it produced G.8031 Linear Ethernet Protection Switching
G.8031 uses standard Ethernet formats, but is incompatible with STP
The standard addresses
 point-to-point VLAN connections
 SNC (local) protection class
 1+1 and 1:1 protection types
 unidirectional and bidirectional switching for 1+1
 bidirectional switching for 1:1
 revertive and nonrevertive modes
 1-phase signaling protocol

G.8031 uses Y.1731 OAM CCM messages in order to detect failures
G.8031 defines a new OAM opcode (39) for APS signaling messages
Switching times should be under 50 ms (only holdoff timers when groups)
Y(J)S APS Slide 98

G.8031 signaling
The APS signaling message looks like this :

MEL VER=0 OPCODE=39 FLAGS=0 OFFSET=4
(3b) (5b) (1B) (1B) (1B)

req/state prot. type requested sig bridged sig reserved
(4b) (4b) (1B) (1B) (1B)
END=0
(1B) – regular APS messages are sent 1 per 5 seconds
– after change 3 messages are sent at max rate (300 per sec)
where
 req/state identifies the message (NR, SF, WTR, SD, forced switch, etc)
 prot. type identifies the protection type (1+1, 1:1, uni/bidirectional, etc.)
 requested and bridged signal identify incoming / outgoing traffic
since only 1+1 and 1:1 they are either null or traffic (all other values reserved)
Y(J)S APS Slide 99

G.8031 1:1 revertive operation
In the normal (NR) state :
 head-end and tail-end exchange CCM (at 300 per second rate)
on both working and protection channels
 head-end and tail-end exchange NR APS messages
on the protection channel (every 5 seconds)
When a failure appears in the working channel
 tail-end stops receiving 3 CCM messages on working channel
 tail-end enters SF state
 tail-end sends 3 SF messages at 300 per second on the APS channel
 tail-end switches selector (bi-d and bridge) to the protection channel
 head-end (receiving SF) switches bridge (bi-d and selector) to protection channel
 tail-end continues sending SF messages every 5 seconds
 head-end sends NR messages but with bridged=normal
When the failure is cleared
 tail-end leaves SF state and enters WTR state (typically 5 minutes, 5..12 min)
 tail-end sends WTR message to head-end (in nonrevertive - DNR message)
 tail-end sends WTR every 5 seconds
 when WTR expires both sides enter NR state
Y(J)S APS Slide

Ethernet rings ?
Ethernet has become carrier grade :
 deterministic connection-oriented forwarding
 OAM
 synchronization
The only thing missing to completely replace SDH is ring protection
However, Ethernet and ring architectures don’t go together
 Ethernet has no TTL, so looped traffic will loop forever
 STP builds trees out of any architecture – no loops allowed
There are two ways to make an Ethernet ring
 open loop
– cut the ring by blocking some link
– when protection is required - block the failed link
 closed loop
– disable STP (but avoid infinite loops in some way !)
– when protection is required - steer and/or wrap traffic
Y(J)S APS Slide 101

Ethernet ring protocols
Open loop methods
 G.8032 (ERPS)
 rSTP (ex 802.1w)
 RFER (RAD)
 ERP (NSN)
 RRST (based on RSTP)
 REP (Cisco)
 RRSTP (Alcatel)
 RRPP (Huawei)
 EAPS (Extreme, RFC 3619)
 EPSR (Allied Telesis)
 PSR (Overture)
Closed loop methods
 RPR (IEEE 802.17)
 CLEER and NERT (RAD)

Y(J)S APS Slide 102

G.8032
Q9 of SG15 produced G.8032 between 2006 and 2008

G.8032 is similar to G.8031
 strives for 50 ms protection (< 1200 km, < 16 nodes)
– but here this number is deceiving as MAC table is flushed
 standard Ethernet format but incompatible with STP
 uses Y.1731 CCM for failure detection
 employs Y.1731 extension for R-APS signaling (opcode=40)
 R-APS message format similar to APS of G.8031
(but between every 2 nodes and to MAC address 01-19-A7-00-00-01)
 revertive and nonrevertive operation defined

However, G.8032 is more complex due to
 requirement to avoid loop creation under any circumstances
 need to localize failures
 need to maintain consistency between all nodes on ring
 existence of a special node (RPL owner)
Y(J)S APS Slide 103

RPL
G.8032 defines the Ring Protection Link (RPL)
as the link to be blocked (to avoid closing the loop) in NR state
One of the 2 nodes connected to the RPL
is designated the RPL owner
Unlike RAD’s RFER
 there is only one RPL owner
 the RPL and owner are designated before setup
 operation is usually revertive

All ring nodes are simultaneously in 1 of 2 modes – idle or protecting
 in idle mode the RPL is blocked
 in protecting mode the failed link is blocked and RPL is unblocked
 in revertive operation
once the failure is cleared the block link is unblocked
and the RPL is blocked again

Y(J)S APS Slide 104

G.8032 revertive operation
In the idle state :
 adjacent nodes exchange CCM at 300 per second rate (including over RPL)
 exchange NR RB (RPL Blocked) messages in dedicated VLAN every 5 seconds
(but not over RPL)
 R-APS messages are never forwarded
When a failure appears between 2 nodes
 node(s) missing CCM messages peek twice with holdoff time
 node(s) block failed link and flush MAC table
 node(s) send SF message (3 times @ max rate, then every 5 sec)
 node receiving SF message will check priority and unblock any blocked link
 node receiving SF message will send SF message to its other neighbor
 in stable protecting state SF messages over every unblocked link
When the failure is cleared
 node(s) detect CCM and start guard timer (blocks acting on R-APS messages)
 node(s) send NR messages to neighbors (3 times @ max rate, then every 5 sec)
 RPL owner receiving NR starts WTR timer
 when WTR expires RPL owner blocks RPL, flushes table, and sends NR RB
 node receiving NR RB flushes table, unblocks any blocked ports, sends NR RB
Y(J)S APS Slide

G.8032-2010
After coming out with G.8032 in 2008 (G.8032v1)
the ITU came out with G.8032-2010 (G.8032v2) in 2010
This new version is not backwards-compatible with v1
but a v2 node must support v1 as well (but then operation is according to v1)

Major differences :
 2 designated nodes – RPL owner and RPL node
 significant changes to
– state machine
– priority logic
– commands (forced/manual/clear) and protocol
 new Wait To Block timer
 supports more general topologies (sub-rings)
subring ring subring
– ladders (For Further Study in v1)
– multi-ring
 ring topology discovery ladder
 virtual channel based on VLAN or MAC address
Y(J)S APS Slide 106

EFM

Ethernet in the First Mile (ex-802.3ah)
EFM bonding
xDSL (2M and 10M)
P2P optics
P2MP optics (EPON)
EFM OAM

AdvEth Slide 107

EFM task force
in IEEE new works starts with a Call For Interest
after which a Study Group is formed to consider a new project
SG was formed in Nov. 2000 to think about Ethernet in the First Mile
the next step is defining a Project Authorization Request
PAR is approved if it passes the 5 criteria
1. Broad market potential
2. Compatibility
3. Distinct identity
4. Technical feasibility
5. Economic feasibility

EFM PAR was approved in Sept 2001
a task force or task group in a WG works on a specific project
it receives a name of the form WG.unique_chars
the EFM task force was called 802.3ah

AdvEth Slide 108

EFM task force (cont.)
a task force reviews proposals
and then produces and refines drafts
when complete the draft goes to WG ballot (need 75%)
EFM went to WG ballot in July 2003
after WG ballot, sponsor ballot (75%)
and then LMSC Standards Body approval
EFM became full standard in June 2004
after approval the standard is published
1 year later available free of charge
it is usually combined with the WG standard at its next revision
EFM was folded into 802.3-2005

AdvEth Slide 109

EFM …
LLC (802.2)
the 802.3ah task force had 4 tracks: OAM (57)
 Copper (now in clause 61) MP MAC (64)
– 10PASS-TS (10M, 750m) (now in clause 62) MAC
– 2BASE-TL (2M, 2.7km) (now in clause 63) reconciliation
– PME aggregation (now in subclause 61.2.2)
MII
 Optics
PCS (61)
– 100M (now in clause 58)
TC (G.993.1)
– 1G (now in clauses 59, 60)
PMA (62/63)
– EPON (now in clause 65 see GPON/GEPON course)
PMD
 P2MP clause 64 (58/59/60/62/63)
– logic to enable EPON (see GPON/GEPON course)
 OAM (see OAM section below) clause 57
PCS = Physical Coding Sublayer
TC = Transmission Convergence
PMA = Physical Medium Attachment
PMD = Physical Medium Dependent AdvEth Slide 110

EFM bonding (PME Aggregation)
Physical Medium Entity inverse MUX (EFM bonding)
Defined in 802.3-2005 61.2.2 and ITU-T G.998.2 (ITU-T allows for ADSL as well)
Optional feature applicable only to copper EFM (DSL) links
PME Aggregation Function (PAF) is part of PCS (between MII and TC)
 fragments Ethernet frame
 forms non-Ethernet fragments (16b header + fragment)

Divides fragments over physical links (mechanism is implementation dependent)
Uses 14-bit sequence number to recover order of fragments
Fragments can be from 64 to 512 bytes in length (all multiple of 4 except EOP)
Fragments delineated by TC layer framing (64/65 octet coding – not HDLC)
Can compensate for
 rate ratios up to 4
 differential delay up to 15,000 bit times
(delay is due to modem interleaving and rate differences)

AdvEth Slide 111

PME Aggregation (cont.)
IPG preamble SFD Ethernet frame IPG
the Ethernet frame from DA SA to FCS is fragmented

PME 1 header fragment 1 CRC header fragment 5 …



PME n header fragment 4 CRC header fragment 8 …
mechanism for choosing fragment size and order is implementation dependent
CRC is 16 bits for VDSL 32 bits for SHDSL with polynomials defined in 802.3 61.3.3.3

Fragmentation header :
sequence number SOP EOP
(14b) (1b) (1b) AdvEth Slide 112

RPR – 802.17

Resilient Packet Rings
resilience and fairness requirements
MAC operation
topology discovery

AdvEth Slide 113

RPR – 802.17
Resilient Packet Rings
 are compatible with standard Ethernet
 are robust (lossless, <50ms protection, OAM)
 are fair (based on client throttling)
 support QoS (3 classes – A, B, C)
 are efficient (full spatial reuse)
ringlet0
 are plug and play (automatic station autodiscovery)
 extend use of existing fiber rings

counter-rotating add/drop ringlets, running ringlet1
 SONET/SDH (any rate, PoS, GFP or LAPS) or
 “packetPHY” (1 or 10 Gb/s ETH PHY)

developed by 802.17 WG
based on Cisco’s Spatial Reuse Protocol (RFC 2892)

AdvEth Slide 114

Why rings?
conventional Ethernet topologies are
point-to-point bus star

while conventional SONET/SDH topologies are rings

advantages of ring topologies
 protection
 fairness
 simple multicast support

RPR mechanisms
– input shaping
– ringlet selection
– buffer insertion
– transit buffer(s)
AdvEth Slide 115

Basic queuing

traffic going around ring traffic for local sink
placed into internal buffer
placed in output buffer
in dual-transit queue mode
according to service class

A
B
C
placed into 1 of 2 buffers
according to service class
sent according to fairness

PTQ

STQ

traffic from local
fairness
A
B
C

Primary/Secondary Transit Queue
source
sent according to fairness
first sent to ringlet selection AdvEth Slide 116

RPR service classes
RPR defines 3 main classes
 class A : real time (low latency/FDV)
 class B : near real time (bounded predictable latency/FDV)
 class C : best effort

class use info rate D/FDV FE

A0 RT reserved low No

A1 RT allocated, low No
reclaimable
B-CIR near RT allocated, bounded No
reclaimable
B-EIR near RT opportunistic unbounded Yes

C BE opportunistic unbounded Yes
AdvEth Slide 117

Class use
A0 ring BW is reserved – not reclaimed even if no traffic
in dual-transit queue mode:
 class A frames from the ring are queued in PTQ
 class B, C in STQ

priority for egress
 frames in PTQ
 local class A frames
 local class B (when no frames in PTQ)
 frames in STQ
 local class C (when no PTQ, STQ, local A or B)

Notes:
class A have minimal delay
class B have higher priority than STQ transit frames, so bounded delay/FDV
classes B and C share STQ, so once in ring have similar delay

AdvEth Slide 118

RPR - fairness

1M 2M 4M 8M 16M

1M 2M 4M 8M

regular Ethernet is inherently unfair!
RPR never discards packets to resolve congestion
instead uses ingress policing
an upstream node can potentially starve a downstream node
when a downstream node experiences BW starvation
it sends a fairness request upstream
upstream node MUST reduce its traffic injection rate
AdvEth Slide 119

RPR - protection

rings give inherent protection against single point of failure
RPR specifies 2 mechanisms
 steering
 wrapping (optional)

(implementations may also do wrapping then steering)

steering info

wrap
AdvEth Slide 120

Twice as efficient as EoS ?
it is frequently said that RPR is twice as efficient as EoS
how could that be true?
RPR has inherent spatial re-use
slots in SONET/SDH rings are typically not re-used
due to management complexity

slot used BW
used

data remains in slot – BW reused
removed by originator
AdvEth Slide 121

RPR - multicast

for regular Ethernet multicast requires replicating frames
for RPR, broadcast/flooding/multicast
simply requires not removing frame from ring
multicast can be unidirectional or bidirectional
when TTL=0 the frame is finally removed

AdvEth Slide 122

RPR frame formats
802.17 defines 4 frame types:
 data frame
ETH MAC frame + TTL, frame type and flag fields
 control frame
attribute discovery, topology, protection, round-trip measure, OAM, etc.
 fairness frame
sent upstream to indicate required fair rate
 idle frame
sent to neighboring node to avoid PTQ overflow due to lack of sync

AdvEth Slide 123

Ethernet OAM

OAM functions
link OAM (802.3ah)
service OAM (Y.1731, 802.1ag)

AdvEth Slide 124

OAM
analog channels and 64 kbps digital channels
did not have mechanisms to check signal validity and quality
thus
 major faults could go undetected for long periods of time
 hard to characterize and localize faults when reported
 minor defects might be unnoticed indefinitely

as PDH networks evolved, more and more overhead was dedicated to
Operations, Administration and Maintenance (OAM) functions
including:
 monitoring for valid signal
 defect reporting
 alarm indication/inhibition

when SONET/SDH was designed
overhead was reserved for OAM functions
today service providers require complete OAM solutions

AdvEth Slide 125

OAM (cont.)
OAM is a user-plane function
but may influence control and management plane operations
for example
 OAM may trigger protection switching, but doesn’t switch
 OAM may detect provisioned links, but doesn’t provision them

OAM is more complex and more critical for PSNs
since in addition to previous problems
 loss of signal
 bit errors

we have new defect types
 packets may be lost
 packets may be delayed
 packets may incorrectly delivered

OAM requirements are different for CO and CL modes

AdvEth Slide 126

ITU-T concept - Trail
since OAM is critical to proper network functioning
OAM must be added to the concept of a connection
a trail is defined as a connection along with integrity supervision
clients gain access to the trail at access points (AP)
the trail termination function is responsible for
generating / processing OAM

trail =
AP AP

TCP TCP

AdvEth Slide 127

Trail Termination Functions
what functionality does the trail termination function add ?
 Continuity Check (e.g. LOS, periodic CC packets)
 Connectivity Verification (detect misrouting)
 signal quality monitoring (e.g. error detection coding)
 defect notification/alarm inhibition (AIS(FDI), RDI(BDI))

source termination functions:
 generates error check code (FEC, CRC, etc)
 returns remote indications (REI, RDI)
 inserts trail trace identification information

sink termination functions:
 detects misconnections
 detects loss of signal, loss of framing, AIS instead of signal, etc.
 detects code violations and/or bit errors
 monitors performance

AdvEth Slide 128

Defects, Faults, etc.
G.806 defines:
anomaly (n): smallest observable discrepancy
between desired and actual characteristics
defect (d): density of anomalies that interrupts some required function
fault cause (c): root cause behind multiple defects
failure (f): persistent fault cause - ability to perform function is terminated
action (a): action requested due to fault cause
performance parameter (p): calculatable value representing ability to function

for example: equipment specifications define relationships
 dLOS = loss of signal defect e.g.
 cPLM = payload mismatch cause aAIS <= dAIS or dLOS or dLOF
 aAIS = insertion of AIS action

alarms are human observable failure indications

AdvEth Slide 129

Supervision Flowchart

pX
performance statistics
monitoring gathering

anomaly nX

defect cX persistence fX
correlation monitoring

defect filter dX

consequent aX
N.B. this is a greatly simplified picture action
more generally there are external
signals, time constants, etc.
AdvEth Slide 130

Ethernet OAM functionality
 Continuity Check / Connectivity Verification

 LoopBacks
– in-service (nonintrusive)
– out-of service (intrusive)
– linktrace

 defect notification / alarm inhibition
– AIS (FDI)
– RDI (BDI)

 performance monitoring
– frame loss
– one-way delay
– round-trip delay
– delay variation
– throughput
AdvEth Slide 131

Two flavors

for many years there was no OAM for Ethernet
now there are two incompatible ones!
Link layer OAM – EFM 802.3ah 802.3 clause 57
single link only
limited functionality
Service OAM – Y.1731, 802.1ag (CFM)
any network configuration
full OAM functionality
in some cases may need to run both (e.g. ETH over ETY)
while in others only service OAM makes sense

AdvEth Slide 132

EFM OAM
EFM networks are mostly p2p links or p2mp PONs
thus a link layer OAM is sufficient for EFM applications
Since EFM link is between customer and Service Provider
EFM OAM entities are classified as active (SP) or passive (customer)
active entity can place passive one into LB mode, but not the reverse
but link OAM may be used for any Ethernet link, not just EFM ones

EFM OAMPDUs are a slow protocol frames – not forwarded by bridges
Ethertype = 88-09 and subtype 03
messages multicast to slow protocol specific group address
OAMPDUs must be sent once per second (heartbeat)
messages are TLV-based

DA TYPE SUB FLAGS CODE
01-80-C2-
SA TYPE (2B) (1B) DATA CRC
00-00-02 8809 03

AdvEth Slide 133

EFM OAM capabilities
6 codes are defined
 Information (autodiscovery, heartbeat, fault notification)
 Event notification (statistics reporting)
 Variable request (active entity query passive’s configuration) (not really OAM)
 Variable response (passive entity responds to query) (not really OAM)
 Loopback control (active entity enable/disable of passive’s PHY LB mode)
 Organization specific (proprietary extensions)

flags are in every OAMPDU
expedite notification of critical events
– link fault (RDI)
– dying gasp
– unspecified
monitor slowly degradations in performance

AdvEth Slide 134

Y.1731 OAM
SPs want to monitor full networks, not just single links
Service layer OAM provides end-to-end integrity
of the Ethernet service over arbitrary server layers

Ethernet is the hardest case for OAM
 connectionless – can’t use ATM-like connection continuity check
 MP2MP – so need full connectivity verification
 layering – need separate OAM for operator, SPs, customer
 specific ETH behaviors – flooding, multicast, etc.

AdvEth Slide 135

Y.1731 messages
Y.1731 supports many OAM message types:
 Continuity Check proactive heartbeat with 7 possible rates
 Synthetic Loss Measurement on demand loss rate estimation
 LoopBack unicast/multicast pings with optional patterns
 Link Trace identify path taken to detect failures and loops
 AIS periodically sent when CC fails
 RDI flag set to indicate reverse defect
 Client Signal Fail sent by MEP when client doesn’t support AIS
 LoCK signal inform peer entity about intentional diagnostic actions
 Test signal in-service/out-of-service tests for loss rate, etc.
 Automatic Protection Switching
 Maintenance Communications Channel remote maintenance
 EXPerimental
 Vendor SPecific

AdvEth Slide 136

Y.1731 frame format
after DA, SA and Ethertype (8902)
Y.1731/802.1ag PDUs have the following header (may be VLAN tagged)

LEVEL VER OPCODE FLAGS TLV-OFF
(3b) (5b) (1B) (1B) (1B)

if there are sequence numbers/timestamp(s), they immediately follow
then come TLVs, the “end TLV”, followed by the CRC

TLVs have 1B type and 2B length fields
there may or not be a value field
the “end-TLV” has type = zero and no length or value fields

AdvEth Slide 137

Y.1731 PDU types
opcode OAM Type DA
1 CCM M1 or U
3 LBM M1 or U
2 LBR U
5 LTM M2
4 LTR U
6-31 RES IEEE
32-63 unused RES ITU-T
33 AIS M1 or U
35 LCK M1or U
37 TST M1 or U
39 Linear APS M1or U
40 Ring APS M1or U
41 MCC M1 or U
43 LMM M1 or U
42 LMR U DA
45 1DM M1 or U
47 DMM M1 or U
46 DMR UA
49 EXM
48 EXR
51 VSM
50 VSR
52 CSF M1 or U
55 SLM U
54 SLR U
64-255 RES IEEE

AdvEth Slide 138

MEPs and MIPs
Maintenance Entity (ME) – entity that requires maintenance
ME is a relationship between ME end points
because Ethernet is MP2MP, we need to define a ME Group
MEGs can be nested, but not overlapped
MEG LEVEL takes a value 0 … 7
by default - 0,1,2 operator, 3,4 SP, 5,6,7 customer
MEP = MEG end point (MEG = ME group, ME = Maintenance Entity)
(in IEEE MEG MA = Maintenance Association)
unique MEG IDs specify to which MEG we send the OAM message
MEPs responsible for OAM messages not leaking out
but transparently transfer OAM messages of higher level
MIPs = MEG Intermediate Points
 never originate OAM messages,
 process some OAM messages
 transparently transfer others

AdvEth Slide 139

MEPs and MIPs (cont.)

AdvEth Slide 140

How do we use all this ?
MEF-30 Service OAM FM and MEF-xx Service OAM PM
Describe the use of OAM for Carrier Ethernet networks, such as
 which Y.1731/802.1 features should be implemented
 which Y.1731/802.1 messages should be used
 what MA names should be used
 where to put MEPs
 how to use MEG levels
 minimum number of EVCs that must be supported
 what should be reported and how

Y.1564 (ex Y.156sam)
Ethernet Service Activation Test Methodology
Details how to check configuration and performance before EVC activation

AdvEth Slide 141

Y.1564
Ethernet Service Activation Test Methodology
Replaces widespread proprietary use of RFC 2544 benchmarking
Tests that desired performance level can be achieved, including
 CIR, EIR (and optionally CBS and EBS for bursting)
 Traffic policing
 Rate, loss, delay, delay variation, availability (measured simultaneously)

Testing in two steps :
 Service Configuration Test – each service separately
 Service Performance Test – all services together

Performance testing may be for :
 15 minutes (new service on operational network)
 2 hours (single operator network)
 24 hours (multiple operator networks)

AdvEth Slide 142

Ethernet security

Security functions
802.1X
MACsec (802.1AE)
MACkey (802.1af, now in 802.1X)

AdvEth Slide 143

Security functions

Some threats that may need to be countered in Ethernet networks
 denial of service (DoS) to all or some stations
 theft of service
 access to confidential information
 modification of information
 control of restricted resources

Some security functions that solve some of these problems
 source authentication
 confidentiality
 data integrity
 replay protection
 non-repudiation
 blocking DoS attacks
 protection against traffic analysis

AdvEth Slide 144

802.1X
802.1X is a port-based access control mechanism
 it enables or blocks traffic from a port

It provides authentication for devices wishing to communicate
It is based on the Extensible Authentication Protocol (RFC3748)
It is used in 802.11i for WiFi (WPA2)

In 802.1X there are three entities :
 the authenticator

 the supplicant

 the authentication server (usually a RADIUS server)

802.1X PDUs use EtherType 88-8E
and multicast address 01-80-C2-00-00-03

AdvEth Slide 145

802.1X operation
Upon detection of a new supplicant
 the authenticator’s switch port is set to unauthorized

 only 802.1X traffic is allowed

The authenticator sends EAP-Request identity to the supplicant
The supplicant responds with EAP-response
The authenticator forwards response to the authenticating (RADIUS) server
If the server accepts the request
 the authenticator sets the port to the "authorized" mode

 traffic from supplicant is allowed in

AdvEth Slide 146

MACsec
802.1AE was approved in June 2006
based on well known AES-128 encryption
but with a new mode - Galois Counter Mode
Main features
 works over Connectionless network by forming secure
associations
 integrated into Ethernet frame format
 key management and association establishment outside scope

802.1AE MACsec provides
 origin authentication
 confidentiality
 connectionless data integrity
 replay protection
 limited blocking of DoS attacks
but may lower some QoS attributes (e.g. introduces bounded delay)

AdvEth Slide 147

MACsec format

DA SA Type payload FCS

DA SA SecTAG (incl. IV) secure data ICV FCS’
optional
confidentiality
integrity
SecTAG contains
 MACsec Ethertype (88E5)
 4B Packet Number (sequence number)
 8B Secure Channel Identifier 12 B Initialization Vector
 …

AdvEth Slide 148

AES/GCM advantages
 encryption is provided by “state-of-the-art” AES (128/256 bit keys)
 mode of operation uses a counter to thwart replay attacks
 Integrity Check Value verifies the payload integrity
 encryption, integrity, and source authentication by a single algorithm
 authentication can be performed without encrypting
 data not in packet payload (e.g. source identifiers) can be authenticated too
 Initialization Vector nonce can be any length (but should not repeat for given key)
 algorithm can be efficiently implemented in software
 computation can be parallelized for high speed hardware implementations
 unencumbered by IPR claims

adopted by IEEE 802.1ae for MACsec and RFCs 4106 and 4543 for IPsec

AdvEth Slide 149

AES/GCM Input / Output
Encryption Input
 plaintext to be encrypted (up to 236-32 bytes)
 encryption key (128 or 256 bits)
 per-packet randomly generated IV (12 B recommended)
 additional data to be authenticated but not encrypted (0 .. 2^61 B)

Encryption Output
 ciphertext (length = length of plaintext)
 ICV (16 B)

Decryption Input
 ciphertext
 encryption key
 IV used for encryption
 ICV generated by encryption

Encryption Output
 Authentication pass/fail
 if pass - plaintext

AdvEth Slide 150

802.1af – absorbed into 802.1X
MACsec peers need to share encryption keys
keys need to be regularly updated

MACkey (802.1af) is a key distribution protocol
provides authenticated distribution of keys needed by MACsec

MACkey defines MAC Key Distribution Protocol Data Units MKDPDUs

Authentication based on Extensible Authentication Protocol (RFC 3748)
uses a centrally administered Authentication Server
MACkey defines EAP encapsulation over LANs (EAPOL)

AdvEth Slide 151

Other 802 security documents
802.1AR - Secure Device Identity
Extends 802.1X specifying unique per-device identifiers (DevID)
Management and binding of a device to its identifiers

802.11i Enhanced WiFi security
WiFi's Wired Equivalent Privacy encryption broken by Biham (Technion)
802.11i (WPA2) amendment approved June 2004
Uses 802.1X/EAP and AES block cipher

802.10 Enhanced WiFi security
Former 802 security protocol (approved 1998)
Had security associations, key management, confidentiality, integrity
Used by Cisco’s Inter Switch Link (ISL) protocol
Withdrawn (Jan 2004) due to lack of use

AdvEth Slide 152

Synchronous Ethernet

synchronizing networks
packet time protocols
synchronous Ethernet physical layer

AdvEth Slide 153

Synchronizing networks
SONET/SDH/PDH/TDM networks require highly accurate timing
in every such network there is a primary reference clock
all other clocks derive timing from the PRC
the clock signal is carried in the physical layer
we can say that such networks distribute data + timing

applications needing accurate timing get it “free”
 cellular base stations
 electric power facilities
 data/modem terminals
 TDMoIP GWs
 high quality audio/video systems

PSNs such as Ethernet have no physical layer clock
and thus do not natively distribute timing
how can we support applications needing timing?
AdvEth Slide 154

Packet time protocols

TDM networks distribute accurate frequency but not wall-clock
RAD has developed methods for adaptive frequency recovery
for TDMoIP applications
There are packet-based protocols for timing distribution, e.g.,
 IETF NTP (over UDP/IP)
 IEEE 1588 (over UDP/IP or pure Ethernet)
both are based on time servers that send timestamps
usually frequency is acquired first, then ranging, then calibration

NTP and 1588 can be used for frequency distribution
present versions are not sufficiently accurate for all applications
1588 can exploit Transparent Clocks and Boundary Clocks

AdvEth Slide 155

Synchronous Ethernet (SyncE)

Ethernet started as a CSMA/CD bursty LAN technology
receiver acquired the transmitter clock by locking onto preamble

But for all continuously transmitting full duplex ETY layers
we can lock clocks based on PHY layer
then synchronous Ethernet distributes clock just like TDM networks

This requires modifications to the Ethernet PHY
but no other changes to network
SyncE can co-exist with nonsynchronous Ethernet
and makes IEEE 1588 wall-clock distribution work even better!

AdvEth Slide 156

ESMC
Synchronous network devices need to identify their clock quality
This is traditionally done using Synchronization Status Messages

G.8264 defines an Ethernet Synchronization Messaging Channel

ESMC frames are slow protocol frames
– with the ITU’s OUI (0x0019A7)
– and a new slow protocol subtype 0x0A

The frames carry a 4-bit SSM code
This code can contain any of the usual SSM values (PRC, SSU, SEC, …)
or one of 2 new values defined for SyncE interfaces

AdvEth Slide 157

Ethernet technology

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Ethernet technology