[c-nsp] LDPv6 Census Check

Mark Tinka mark.tinka at seacom.mu
Thu Jun 11 09:21:04 UTC 2020

On 11/Jun/20 10:32, adamv0025 at netconsultings.com wrote:

> Hey Mark,
> My stance is that should I go with anything "new" for label distribution the
> MPLS SR/SPRING is getting to a point where it might be mature enough.

"Getting to a point" doesn't really work if you are actively running a
network today :-).

While I do agree that going with the new thing is always a good plan,
one has to truly consider the overall gain vs. labour required to get there.

Going from static routing to an IGP + BGP makes sense when you scale up.

Switching from Distribute Lists to Prefix Lists makes sense when you
scale up.

Route summarization after you dump your old Cisco 2501 for an ASR9901
doesn't add value any longer.

You get the idea.

The position about not needing a label distribution protocol in SR is
actually quite sexy. But considering how powerful router control planes
are nowadays, especially when they are being virtualized on or off
chassis, I just don't see the gains expected by removing LDP and going
SR, on a box and code that supports both. Yes, if you are talking about
dumping a spaghetti of RSVP tunnels, that makes sense as there is a gain
in day-to-day network administration. But in this case, we are just
speaking about LDP.

10 years ago, we worried about how well an IP network would scale
running OSPF or IS-IS. With control planes what they are today, who
really cares anymore? You may recall we've been running CSR1000v for
route reflection since 2014 - millions of routes being carried everyday,
converging in seconds. We've never had to think about those boxes until
last year when we did the server hardware refresh as a matter of course,
not because anything was struggling.

What I'm saying is not all new tech. NEEDS to get deployed just because
it's new. If that was the case, we'd all be running Inter-AS DSCP over
IPoDWDM :-).

> Also "BGP free core" means internet won't talk to your core -i.e. free to
> use private addressing -so no need for v6 at all in the "underlay" (as
> hipsters call it these days).

Careful with that one - Cisco's proposal to me was to run my IPv6
network on link-local :-). Don't encourage them, hehe.

> Alternatively using public "infrastructure subnet" (i.e. not advertised to
> the Internet) for a "BGP free core", the aim is to make money of the core
> -what additional revenue stream am I getting by enabling v6 in the
> underlay/management plane that would offset the pain of dealing with the
> increased bug surface?  

I don't know about you, but my BGP-free core is inaccessible from the
world even if it lives in public-IPv4 land. That's how pure MPLS
forwarding works. You'd have be "inside" to reach it (IGP).

Also, if you link every feature to a revenue stream, you'll never deploy

> And with regards to the XE/XR discrepancies, I mentioned my prophecy a
> number of times, I think XE future in SP products portfolio is next to none.

Which is fine - but customers are spending real money and need to keep
real networks running with real costs for real years. If Cisco want to
kick IOS XE to the side, let customers know so we can make informed
decisions about where to purchase gear.

The current state-of-the-art is that kit you buy today is probably good
years after standard depreciation policies, probably longer. If Cisco's
model is to throw boxes away sooner than that like they did in the old
days, that is not consistent with where the tech. has gotten to in the
past 2 decades.

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