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 RPKI or DNSSEC :-).
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.
Mark.