Dual-Homing Protection for MPLS and
MPLS-TP Pseudowires
Weiqiang Cheng, L. Wang, H. Li (China Mobile)
K. Liu, J. Dong (Huawei)
S. Davari (Broadcom)
A. D'Alessandro (Telecom Italia)
IETF91 PALS Honolulu 2014
Background
• Work was presented in IETF 88 and 90
• Split the draft according to PWE3 chairs’ suggestion:
– Framework and scenarios of dual-homing PW protection
– Protocol extensions for dual-homing protection with static
MPLS-TP PWs
Benefits of Dual-homing Protection
• Local protection
– Avoid PW switchover due to AC failure
– Avoid AC switchover due to PW failure
• PSN tunnel protection is no longer a MUST
PE Architecture Update
AC
Dual-homing PE Device
Forwarder
Service PW
Service PW
DNI PW
DNI PW
Peer Dual-homing PE Device
• DNI PW between dual-homing PEs can carry traffic during failure
• Forwarder is responsible for switching traffic between AC, service
PW and DNI PW.
One-side Dual-homing Scenario
linear protection
PE1
Working PW
CE2
PE3
Protection PW
Service PW
AC1
DNI
PW
Service PW
PE2
CE1
AC2
linear protection
dual-homing coordination
• Can Provide protection for:
– AC failure
– PE failure
– PSN network failure
AC
Redundancy
Mechanism
One-side Dual-homing Scenario
linear protection
PE1
1
Working PW
CE2
AC1
DNI
PW
PE3
Protection PW
PE2
CE1
AC2
linear protection
dual-homing coordination
• Can Provide protection for:
– AC failure
– PSN network failure
– PE failure
AC
Redundancy
Mechanism
One-side Dual-homing Scenario
linear protection
PE1
Working PW
CE2
2
PE3
Protection PW
AC1
DNI
PW
PE2
CE1
AC2
linear protection
dual-homing coordination
• Can Provide protection for:
– AC failure
– PSN network failure
– PE failure
AC
Redundancy
Mechanism
One-side Dual-homing Scenario
linear protection
3
PE1
AC1
Working PW
CE2
DNI
PW
PE3
Protection PW
PE2
CE1
AC2
linear protection
dual-homing coordination
• Can Provide protection for:
– AC failure
– PSN network failure
– PE failure
AC
Redundancy
Mechanism
Two-side Dual-homing Scenario
linear protection
2
PE3
1
CE2
AC
redundancy
mechanism
Working PW
AC1
5
DNI
PW
DNI
PW
PE3
3
4
PE1
Protection PW
linear protection
• Can Provide protection for:
– AC failure
– PE failure
– PSN network failure
PE2
CE1
AC2
AC
Redundancy
Mechanism
General Procedures
• Dual-homing PEs need to exchange PW state and
switchover coordination request to synchronize the
protection switching
• Forwarding behavior of dual-homing PE is determined by:
– Status of Service PW
– Status of AC
– Status of DNI PW
Service PW
AC
DNI PW
Service PW
AC
DNI PW
Forwarding Behavior
Active
Active
Up
Service PW <-> AC
Active
Standby
Up
Service PW <-> DNI PW
Standby
Active
Up
DNI PW <-> AC
Standby
Standby
Up
Drop all packets
Next Steps
• Solicit comments from WG
• WG adoption?