nanog mailing list archives

Re: [c-nsp] LDPv6 Census Check


From: Mark Tinka <mark.tinka () seacom mu>
Date: Thu, 11 Jun 2020 12:15:16 +0200



On 11/Jun/20 11:57, Robert Raszuk wrote:


Nope that was not the main reason. 

Main reason was the belief that labels MUST be locally significant -
and not domain wide unique. Just look at Juniper's SRm6 or now SRH ...
they keep this notion of locally significant SIDs. It is deep in their
DNA ... still. 

We argued about it a lot in cisco back in TDP days - and we lost.

I get this for VLAN's, being only 4,096 per broadcast domain and all.

But are we struggling with scaling label space?

Just my 1+1, since I may be over-simplifying the issue.



- - -

Now to your runt that MPLS is great because of exact match perhaps you
missed it but number of solutions on the table (including RbR[**] I
recently proposed) use exact match 4B locator based lookup in the v6
packets to get from segment end to segment end. 

On the other hand your comments about greatness of MPLS ... simplified
data plane and depending on the hardware difference in jitter (in sub
ms ranges - if that even matters) comes up with a lot of control plane
complexity when you want to build a network across all continents, yet
keep it scoped from IGP to areas or levels. No summarization in MPLS
in FECs is something we should not sweep under the carpet.

I found multi-level IS-IS to be useless in an MPLS network because you
still need to leak routes between L2 and L1 in order to form MPLS FEC's.
So you simplify the network by having a single L2 (or just Area 0 in
OSPF), because today's control planes can handle it. And yes, some are
brave enough to run RFC 3107 if it becomes a problem, but if you can
afford to string a network together across all continents, I doubt an
x86-based control plane with 64GB of RAM is topping the list of your
problems.

Mark.

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