Just wondering if SRLGs are carried through between IGP areas, both for OSPF and for IS-IS?
The scenario for this would be passing a cspf routed RSVP LSP from PE1 in Area 1 through to PE2 in Area 2. We would maintain a secondary standby LSP path for this traffic with exclude-srlg enabled.
Assuming that the primary path takes the IGP routed path PE1 - ABR1 - ABR3 - PE2 then the secondary path will take the path PE1 - ABR2 - where?
If SRLGs are carried through by the IGP then then the path should go PE1 - ABR2 - ABR4 - PE2, however if the SRLGs are not carried through then the IGP could in make the secondardy path PE1 - ABR2 - ABR3 - PE2 which obviously is not a great standby secondary path...
/--- ABR1 ---| |--- ABR3 ---\
PE1 (Area1) | Area 0 | (Area2) PE2
\--- ABR2 ---| |--- ABR4 ---/
If anybody knows this scenario and can shed some insight it would be greatly appreciated 🙂