Hi Shraddha:
MPLS egress protection is a FRR mechanism, PUA is a hard convergence
mechanism. I don't think there's a conflict between the two solution.
Also, as far as I know, MPLS egress protection has not been deployed on a large
scale.
Thanks
Zhibo
From: Lsr [mailto:[email protected]] On Behalf Of Shraddha Hegde
Sent: Wednesday, November 24, 2021 1:20 PM
To: Tony Li <[email protected]>; Aijun Wang <[email protected]>
Cc: Les Ginsberg (ginsberg) <[email protected]>; Gyan Mishra
<[email protected]>; Christian Hopps <[email protected]>; lsr
<[email protected]>; Acee Lindem (acee) <[email protected]>; Tony Przygienda
<[email protected]>
Subject: Re: [Lsr] 【Responses for Comments on PUAM Draft】RE: IETF 112 LSR
Meeting Minutes
WG,
MPLS egress protection framework RFC 8679 provides a mechanism to locally
protect the traffic during
PE failures. The concepts can be applied to SRv6 as well. This mechanism is
much more efficient and quick because it locally provides fast protection
And switchover to the other PE.
If you compare this to the mechanisms being discussed in this thread where
the failure information is being
propagated by the egress PE to ABR and then ABR to the ingress, the failover
is going to be much slower.
The egress protection technology does not flood any information outside of the
domain and hence does not
affect the IGP scale.
This is a valid alternate solution to solve the problem at hand IMO.
I would be interested to see if people have use cases where egress protection
can’t be applied.
Rgds
Shraddha
Juniper Business Use Only
From: Lsr <[email protected]<mailto:[email protected]>> On Behalf Of Tony
Li
Sent: Tuesday, November 23, 2021 10:22 PM
To: Aijun Wang <[email protected]<mailto:[email protected]>>
Cc: Les Ginsberg (ginsberg) <[email protected]<mailto:[email protected]>>;
Gyan Mishra <[email protected]<mailto:[email protected]>>; Christian
Hopps <[email protected]<mailto:[email protected]>>; lsr
<[email protected]<mailto:[email protected]>>; Acee Lindem (acee)
<[email protected]<mailto:[email protected]>>; Tony Przygienda
<[email protected]<mailto:[email protected]>>
Subject: Re: [Lsr] 【Responses for Comments on PUAM Draft】RE: IETF 112 LSR
Meeting Minutes
[External Email. Be cautious of content]
Hi Aijun,
I object to adding negative liveness to the LSDB because of the scale and
because it adds scale during failures.
[WAJ] If we have no such mechanism, operator should either advertise the host
routes across areas(which has scale problem), or lose the fast convergences for
some overlay services(which defeat the user experiences).
Within the real network, there is very rare chance for the massive failure. And
even such thing happen accidently, the information about node liveness is
countable, is there any router can’t process such information?
The received unreachable information does not trigger the SPF calculation. Will
they influence intensively the performance of the router?
If the scale is equal, then I would prefer to see flooding positive information
rather than negative information. Operationally this is key: if there is a
failure and positive information doesn’t propagate, then it’s a bug that will
be found in due course and the operator can react outside of a failure scenario.
Having a scale failure on top of a topology failure is a far more painful
scenario.
The odds of a mass failure may be low. The fact of the matter is that they
still happen. It is our job to ensure that the IGP performs well when it does.
Increasing the size of the LSDB always affects performance. It slows flooding.
Some nodes may not realize that SPF is not needed. When LSP fragments are
rearranged, inferring that SPF is not necessary is non-trivial. Impacting
router and network performance is a given.
My understanding is that N node failures would result in O(N) bytes added to
the LSDB. If someone has a way to compress that information to O(1), I (and
Claude Shannon) would be interested.
[WAJ] Do you have other determined solutions except the PUB/SUB mechanism that
does not exist in current IGP?
None of the mechanisms being discussed currently exist.
I have no objections to Robert’s BGP propagation ideas if that’s workable.
This is simply not the IGP’s job and the IGP is not a dump truck.
Tony
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