![VCCV Stitching procedure for CC Type 3
5
S-PE1 T-PE2
T-PE1
LSP1 LSP2
PW Segment
(with CC Type 3 and no CW)
PW Segment
(with CC Type 1 and CW)
LSP1
PW1 (S=1) [1]
OAM
PDU
LSP2
PW2 (S=1) [1]
OAM
PDU
ACH (CT=IPv4/v6) [2]
IP Header IP Header
[1] S-PE1 needs to know the TTL distance in the PW layer to T-PE1 and
T-PE2 to differentiate between VCCV messages and data packets
[2] ACH Channel Type is set based on the IP version in the IP header
PW label swapped
PW-TTL decremented
ACH added/removed](https://image.slidesharecdn.com/17122690-231011013534-1a60569c/85/17122690-ppt-5-320.jpg)
![CW Stitching Signalling
6
S-PE1 T-PE2
T-PE1
LSP1 LSP2
PW Segment
(no CW)
PW Segment
(with CW)
C=0
[C=1 -> ]C=0
C=1
C=1
Protocol rules implemented by S-PE1 to be updated
• S-PE1 behaves on one PW segment as if support for CW
has been always signalled on the other PW segment
No protocol changes needed on T-PE1 and T-PE2](https://image.slidesharecdn.com/17122690-231011013534-1a60569c/85/17122690-ppt-6-320.jpg)
17122690.ppt
- 1. Italo Busi (Huawei) Stewart Bryant (Huawei) Andrew G. Malis (Huawei) Dongjie (Huawei) draft-busi-pals-pw-cw-stitching-00 IETF 102 – Montreal
- 2. Problem Statement • Being capable of sending Ethernet PW packets with the CW when at least one T-PE is not capable to insert the CW • draft-ietf-pals-ethernet-cw describes why use of the CW is RECOMMENDED for Ethernet PWs – Use of the PW CW is not possible when at least one T-PE is not capable to use it • Replacing the old piece of equipment is a possible solution but not always viable – This draft does not preclude the possibility of replacing the old piece of equipment but provides an alternative option in case replacement is not viable/desired 2 MPLS Network with ECMP T-PE1 T-PE2 Not capable to insert CW Capable to insert CW
- 3. Proposal • Introduce a new S-PE type which is capable to switch an Ethernet PW segment, using the CW, with an Ethernet PW segment, not using the CW – It is easier to ensure control no ECMP behavior over a Link or a small-sized network – It is expected that T-PE1 and S-PE1 are one-hop away at the MPLS layer • This new S-PE can be added to the network with minimum or no service disruption – PW redundancy can be used to move the traffic from the original SS-PW to the new MS- PW (using CW on the PW segment setup over an MPLS network with ECMP) • It is assumed that T-PE1 is able to operate without being aware of whether it is terminating SS-PW or MS-PW (RFC 6073) 3 MPLS Network with ECMP T-PE1 T-PE2 S-PE1 PW Segment (w/o CW) over an LSP without ECMP PW Segment (with CW)
- 4. CW Stitching procedure 4 S-PE1 T-PE2 T-PE1 LSP1 LSP2 PW Segment (no CW) PW Segment (with CW) LSP1 PW1 (S=1) Ethernet Frame LSP2 PW1 (S=1) Ethernet Frame CW PW label swapped PW-TTL decremented CW added/removed
- 5. VCCV Stitching procedure for CC Type 3 5 S-PE1 T-PE2 T-PE1 LSP1 LSP2 PW Segment (with CC Type 3 and no CW) PW Segment (with CC Type 1 and CW) LSP1 PW1 (S=1) [1] OAM PDU LSP2 PW2 (S=1) [1] OAM PDU ACH (CT=IPv4/v6) [2] IP Header IP Header [1] S-PE1 needs to know the TTL distance in the PW layer to T-PE1 and T-PE2 to differentiate between VCCV messages and data packets [2] ACH Channel Type is set based on the IP version in the IP header PW label swapped PW-TTL decremented ACH added/removed
- 6. CW Stitching Signalling 6 S-PE1 T-PE2 T-PE1 LSP1 LSP2 PW Segment (no CW) PW Segment (with CW) C=0 [C=1 -> ]C=0 C=1 C=1 Protocol rules implemented by S-PE1 to be updated • S-PE1 behaves on one PW segment as if support for CW has been always signalled on the other PW segment No protocol changes needed on T-PE1 and T-PE2
- 7. VCCV Stitching Signalling 7 Protocol rules implemented by S-PE1 to be updated • S-PE1 advertises support for CC Type 1 to T-PE2 only if T-PE1 has advertised support for a CC Type S-PE1 is capable to stitch to CC Type 1 • S-PE1 advertises to T-PE1 support for all the CC Types it is capable stitch to CC Type 1 only if T-PE2 advertises support for CC Type 1 • S-PE1 can advertise support for ACH-based CV types if and only if it supports VCCV stitching for CC Type 4 No protocol changes needed on T-PE1 and T-PE2 S-PE1 T-PE2 T-PE1 LSP1 LSP2 PW Segment (no CW) PW Segment (with CW) CC Type 2 or 3 CC Type 1 CC Type 1, 2 or 3 CC Type 3 or 4
- 8. Other Deployment Scenarios 8 MPLS Network with ECMP T-PE1 T-PE2 S-PE1 PW Segment (w/o CW) over an LSP without ECMP S-PE2 PW Segment (with CW) PW Segment (w/o CW) over an LSP without ECMP T-PE1 T-PE2 S-PE1 S-PE4 PW Segment (with CW) over an LSP with or without ECMP PW Segment (w/o CW) over an LSP without ECMP S-PE2 S-PE3
- 9. Next Steps • Validate the current assumptions – How many devices not being capable to use the PW CW exist in the network? – What are their capabilities in terms of CC/CV types and (re-)configuration of TTL? • Further comments to improve the proposal are welcome 9