[c-nsp] Per-CE VPN Label vs BGP-PIC was: ASR9001 BGP scaling and memory shortage

[adamv0025 at netconsultings.com]

> Vladimir Troitskiy
> Sent: Monday, May 25, 2020 7:00 PM
> 
> Hello everyone,
> 
> Other list members have a significantly lower memory usage for a BGP
> process and a shmwin on ASR9001 routers with more sessions/routes in GRT.
> 
> Saku Ytti has suggested me some useful notes which I would like to mention
> as a summary for this thread:
> - one could use 'hw-module profile scale l3xl' in admin mode to increase an
> RLIMIT for a BGP process, even on Typhoon-based platforms (not only on
> Trident-based ones as I thought);
> - a shmwin shortage is probably caused by per-prefix label mode, the per-ce
> mode will be much more scalable. We use the per-prefix mode because of
> BGP PIC limitations, but maybe it's time to reconsider the feature-set used.
> 
I think the notion that BGP PIC is not compatible with per-ce label allocation mode is a myth due to mistake in documentation or maybe some bug that got resolved or maybe related to some pre-asr9k XR HW?
(also description of feature Resilient Per-CE Label Allocation Mode -makes no sense at all)
Would be glad if anyone could please walk me through why it is ,or better, was supposed to be a problem on XR platforms?

To me it boils down to for example:
Primary & backup PE with per-prefix VPN label 
POP VPN Label 100 (for prefix A) --> port 1, mac 00-53-AA
POP VPN Label 100 (for prefix A) --> backup: port 2, VPN Label 300, Transport Label 123, mac 00-53-CC
POP VPN Label 200 (for prefix B) --> port 1, mac 00-53-AA
POP VPN Label 200 (for prefix B) --> backup: port 2, VPN Label 400, Transport Label 123, mac 00-53-CC
Vs
Primary & backup PE with per-ce/NH VPN label
POP VPN Label 100 (for prefix A) --> port 1, mac 00-53-AA
POP VPN Label 100 (for prefix A) --> backup: port 2, VPN Label 300, Transport Label 123, mac 00-53-CC
POP VPN Label 100 (for prefix B) --> port 1, mac 00-53-AA
POP VPN Label 100 (for prefix B) --> backup: port 2, VPN Label 300, Transport Label 123, mac 00-53-CC


adam