Port aggregation
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1. The document describes how to configure port aggregation or EtherChannel on Cisco switches to bundle multiple network links together. 2. EtherChannel allows scaling of bandwidth by treating multiple physical ports as one logical trunk. It provides link redundancy so if one link fails, traffic moves to another link. 3. The Cisco switches support two aggregation protocols: PAgP (proprietary Cisco) and LACP (standard). Both sides must use the same protocol and configuration.
![A.K. Gautam
ciscobulls@gmail.com
switch(config-if-range)# channel-group number mode {active | on | {auto [non-
silent]} | {desirable [non-silent]} | passive}
if No PAgP or LACP negotiation used
switch(config)# interface range fa 0/1 – 4
switch(config-if-range)# channel-protocol pagp
switch(config-if-range)# channel-group 1 mode on
active Enable LACP unconditionally
auto Enable PAgP only if a PAgP device is detected
desirable Enable PAgP unconditionally
on Enable Etherchannel only
passive Enable LACP only if a LACP device is detected
Note: - Both ends must be on
PAgP (Port Aggregation Protocol)
PAgP modes: -
1: -Desirable
2: -Auto
1:- in this mode switch sends a request to neighbor switch for either channel negotiation.
2:- in this mode a switch read for negotiation but it does not send a request to neighbor switch for either channel
negotiation.
Switch1(config)# interface range fa 0/1 – 4
Switch1(config-if-range)#switchport mode trunk
Switch1(config-if-range)# switchport trunk encapsulation dot1q
Switch1(config-if-range)# channel-protocol pagp
Switch1(config-if-range)# channel-group 1 mode desirable
Switch2(config)# interface range fa 0/1 – 4
Switch2(config-if-range)#switchport mode trunk
Switch2(config-if-range)#switchport trunk encapsulation dot1q
Switch2(config-if-range)# channel-protocol pagp
Switch2(config-if-range)# channel-group 1 mode auto
Note: - Load balancing does not have to match.
switch1(config)# port-channel load-balance dst-ip
switch2(config)# port-channel load-balance src-dst-ip
Verifying: -
Switch#show etherchannel protocol
Switch#show etherchannel load-balance
Switch#show ehterchannel summary
Switch#show etherchannel port](https://image.slidesharecdn.com/portaggregation-120217045136-phpapp01/85/Port-aggregation-6-320.jpg)
Port aggregation
- 1. A.K. Gautam ciscobulls@gmail.com CCNP SWITCH PORTABLE STUDY GUIDE & PRACTICE WORK BOOK ANUJ KUMAR email:- ciscobulls@gmail.com anuj_dev007@yahoo.com networkbulls.com
- 2. A.K. Gautam ciscobulls@gmail.com PORT AGGREGATION/ETHERCHANNEL Spanning tree protocol only allows a single link between switch to switch because it prevents bridge loop. Cisco Ether channel technology allows for the scaling of the link bandwidth by aggregating or bundling parallel links. In Ether channel treats multiple line as a single link, logical link. The ether channel allows for two or eight links. The Cisco catalyst family of switches supports two types of link aggregation. PAgP (port aggregation protocol): - It is cisco proprietary protocol. It is default protocol, when we port channel created. LACP (link aggregation control protocol): - It is industy standard protocol. Its standard IEEE 802.3ad based protocol. Etherchannel provide redundancy. If one link fails traffic is automatically moved to another link. Conditions:- 1. Both side same media type and speed. 2. Same duplex. 3. Same Vlan(If access) 4. Same trunking encapsulation and mode(if trunk) 5. Same native vlan. Note: - Load is not balanced equally across links. Etherchannel uses a hashing algorithm. Two inputs are used (Source IP address and Destination IP address) How this work. We will focus on the 2, 4, or 8 link because it is easier to understand for you. A 2 link Etherchannel bundle require a 1 bit index using an XOR. If the index is 0, link 0 is selected. If the index is 1, link 1 is selected. A 4 link Etherchannel bundle requires a 2 bit index using an XOR. 4 possible links: 00, 01, 10, 11 Let’s See 00 = link 0 01 = link 1 10 = link 2 11 = link 3 An 8 link etherchannel bundle requires a 3 bit index using an XOR. 8 possible links: 000, 001, 010, 011, 100, 101, 110, 111. Same as:- 000 = link 0 001 = link 1 010 = link 2 011 = link 3 100 = link 4 101 = link 5 110 = link 6 111 = link 7 Note: - XOR (Exclusive OR), 0 value = false, 1 value = True. If boot bits have same value (both 0, both 1), the XOR will result in a 0. Otherwise, if these value are different (one is a 0 and other is a 1), the result will be 1.
- 3. A.K. Gautam ciscobulls@gmail.com Example: 2 Link EtherChannel. Packet sent from 172.16.1.1 to 10.10.10.16. The chosen hash uses Source IP (172.16.1.1) and Destination IP (10.10.10.16) address. 172.16.1.1 => 00000001 (Source IP address) 10.10.10.16 => 00001000 (Destination IP address) In our example we have 2 links in the EtherChannel (1 bit index): The XOR is performed only one rightmost(right side) bit 1 XOR 0 1 XOR 0 = 1 Link 1 is used Note: - XOR of the two bits result in 0, then link 0 is used. If XOR of the two bits result in 1, then link 1 is used. Example: 4 Link EtherChannel. Link 0 Link 3 Packet sent from 172.16.1.1 to 10.10.10.46. The chosen hash uses Source IP (172.16.1.1) and Destination IP (10.10.10.46) address. 172.16.1.1 => 00000001 (Source IP address) 10.10.10.46 => 00001110 (Destination IP address) In our example we have 4 links in the EtherChannel (2 bit index): The XOR is performed only 2 rightmost (right side) bit 01 XOR 00 Each bit is computed separately 01 XOR 10 = 11 1 XOR 0 = 1
- 4. A.K. Gautam ciscobulls@gmail.com 0 XOR 1 = 1 According to link 0 XOR 0 = 0 link = 0 0 XOR 1 = 1 link = 1 1 XOR 0 = 1 link = 2 1 XOR 1 = 0 link = 3 Link 0 Example: 4 Link EtherChannel Link 7 Packet sent from 172.16.1.1 to 10.10.10.46. The chosen hash uses Source IP (172.16.1.1) and Destination IP (10.10.10.46) address. 172.16.1.1 => 00000001 (Source IP address) 10.10.10.46 => 00001110 (Destination IP address) If there are 8 links in the EtherChannel (3 bit index): The XOR is performed only on the 3 rightmost bits 001 XOR 110 Each bit is computed separately 001 XOR 110 = 111 1 XOR 0 = 1 0 XOR 1 = 1 0 XOR 1 = 1 According to link 8 possible links: 000, 001, 010, 011, 100, 101, 110, 111. Same as:- 000 = link 0 001 = link 1 010 = link 2 011 = link 3 100 = link 4 101 = link 5 110 = link 6 111 = link 7 See more Information:- http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml
- 5. A.K. Gautam ciscobulls@gmail.com CONFIGURE ETHERCHANNEL LOAD BALANCING. EthjerChannel On On PAgP Negotiated EtherChannel Desirable EtherChannel Auto LACP Negotiated EtherChannel Active Passive Load balancing configure on Global mode. Switch(config)# port-channel load-balance method Switch(config)# port-channel load-balance ? dst-ip Dst IP Addr bits dst-mac Dst Mac Addr bits src-dst-ip Src XOR Dst IP Addr XOR src-dst-mac Src XOR Dst Mac Addr XOR src-ip Src IP Addr bits src-mac Src Mac Addr bits EtherChannel protocol The Cisco Catalyst family of switches supports both: Port Aggregation Protocol (PAgP) - Cisco proprietary (Default when port channel is created). Link Aggregation Control Protocol (LACP) - Industry standard 802.3ad-based protocol (When a Cisco switch is connected to a non-Cisco switch use LACP) Note: - Must be same protocol on the both side. switch(config)# interface range fa 0/1 - 4 switch(config-if-range)# channel-protocol ? lacp Prepare interface for LACP protocol pagp Prepare interface for PAgP protocol switch(config-if-range)# channel-protocol pagp Channel-group number: 1 – 64 (Does not need to be the same on both switches but it’s recommended that it usually is) switch(config)# interface range fa 0/1 - 4 switch(config-if-range)# channel-protocol ? lacp Prepare interface for LACP protocol pagp Prepare interface for PAgP protocol
- 6. A.K. Gautam ciscobulls@gmail.com switch(config-if-range)# channel-group number mode {active | on | {auto [non- silent]} | {desirable [non-silent]} | passive} if No PAgP or LACP negotiation used switch(config)# interface range fa 0/1 – 4 switch(config-if-range)# channel-protocol pagp switch(config-if-range)# channel-group 1 mode on active Enable LACP unconditionally auto Enable PAgP only if a PAgP device is detected desirable Enable PAgP unconditionally on Enable Etherchannel only passive Enable LACP only if a LACP device is detected Note: - Both ends must be on PAgP (Port Aggregation Protocol) PAgP modes: - 1: -Desirable 2: -Auto 1:- in this mode switch sends a request to neighbor switch for either channel negotiation. 2:- in this mode a switch read for negotiation but it does not send a request to neighbor switch for either channel negotiation. Switch1(config)# interface range fa 0/1 – 4 Switch1(config-if-range)#switchport mode trunk Switch1(config-if-range)# switchport trunk encapsulation dot1q Switch1(config-if-range)# channel-protocol pagp Switch1(config-if-range)# channel-group 1 mode desirable Switch2(config)# interface range fa 0/1 – 4 Switch2(config-if-range)#switchport mode trunk Switch2(config-if-range)#switchport trunk encapsulation dot1q Switch2(config-if-range)# channel-protocol pagp Switch2(config-if-range)# channel-group 1 mode auto Note: - Load balancing does not have to match. switch1(config)# port-channel load-balance dst-ip switch2(config)# port-channel load-balance src-dst-ip Verifying: - Switch#show etherchannel protocol Switch#show etherchannel load-balance Switch#show ehterchannel summary Switch#show etherchannel port
- 7. A.K. Gautam ciscobulls@gmail.com LACP (Link Aggregation control Protocol) LACP Modes: - 1: -Active: 2: -Passive: 1: - An interface in the active mode can negotiation an EtherChannel with another interface that is in the active or passive mode. 2: - An interface in the passive mode cans negotiation an EtherChannel with another interface that is in the active mode. Note: - An interface in the passive mode cannot negotiation an EtherChannel with another interface that is also in the passive mode because neither interface starts LACP negotiation. Switch1(config)# interface range fa 0/1 – 4 Switch1(config-if-range)#switchport mode trunk Switch1(config-if-range)# switchport trunk encapsulation dot1q Switch1(config-if-range)# channel-protocol lacp Switch1(config-if-range)# channel-group 1 mode active Switch2(config)# interface range fa 0/1 – 4 Switch2(config-if-range)#switchport mode trunk Switch2(config-if-range)#switchport trunk encapsulation dot1q Switch2(config-if-range)# channel-protocol lacp Switch2(config-if-range)# channel-group 1 mode passive Port Priority LACP uses the port priority to decide which port should be put in standby mode. Ports with lower priority are active, and rest ports are standby (Default 32678). For Example we use 4 links. Switch1(config)# interface range fa 0/1 – 2 Switch1(config-if-range)#switchport mode trunk Switch1(config-if-range)# switchport trunk encapsulation dot1q Switch1(config-if-range)# channel-protocol lacp Switch1(config-if-range)# channel-group 1 mode active Switch1(config-if-range)#lacp port-priority 99 Switch1(config)# interface range fa 0/3 – 4 Switch1(config-if-range)#switchport mode trunk Switch1(config-if-range)#switchport trunk encapsulation dot1q Switch1(config-if-range)# channel-protocol lacp Switch1(config-if-range)# channel-group 1 mode passive Note: - Load balancing does not have to match. switch1(config)# port-channel load-balance dst-ip switch2(config)# port-channel load-balance src-dst-ip Verifying: - Switch#show etherchannel protocol
- 8. A.K. Gautam ciscobulls@gmail.com Switch#show etherchannel load-balance Switch#show ehterchannel summary Switch#show etherchannel port Thanks giving me your precious time. A.K. Gautam