[c-nsp] LDPv6 Census Check

Mark Tinka mark.tinka at seacom.mu
Thu Jun 11 09:48:17 UTC 2020

On 11/Jun/20 09:58, Radu-Adrian FEURDEAN wrote:

> Well, given their (Cisco's) braindead policy regarding non-implementation of LDPv6 on XE, no wonder people are looking for alternatives, and SRv6 is one of them.

Which doesn't track because there are a number of IOS XE boxes that do
not support SRv6, and probably never will. Meanwhile, no issue with
those boxes supporting LDPv6, as they already support LDPv4.

>  And don't forget SRv6 is also heavily associated (marketing-wise) with 5G....

Well, we all know the farce that is 5G.

Also, not all of us run mobile networks, and even for those that do,
there are probably a few that don't buy into the snake oil, especially
those that offer native IPv6 to their mobile customers :-).

> Back to our friends and their policy: It happens that in certain regions of the world, if you want to be an ISP other than the "establishment" (== incumbent + "first alternatives" that started 20-25 years ago), you MUST have LNS (if you want to stay in business). If like many, you are kind of stuck with Cisco because it's Cisco, the only decent solution to have LNS is ASR1K (running XE). Also add ASR920 which has a number of uses. Also, in order to stay in business, you may want to offer L3VPN services, which brings you to doing MPLS. You say MPLS, you say LDP, and there you go, your backbone remains v4-based for the next eternity.

Which I would understand if Cisco's strategy, as a company, was anti-LDP.

But when you have the IOS XR team actively supporting LDP and adding new
features with each major release, the split brain is obvious. You can't
come to me under a "unified" organizational banner, and then tell me you
are a-thousand companies internally. If you choose to fork code into
IOS, IOS XE, IOS XR, NX OS, or whatever new flavour of the decade, don't
make that my problem. Customers don't buy code; they buy boxes that are
built for the task. The code that comes with it is the code that comes
with it.

Moreover, IOS XE also has its own split BU's. So getting IOS XE fixed
for the ASR920 doesn't necessarily mean you get it fixed for the
ASR1000. I mean, how much more complicated does a business have to be?

> There also seems to be a lack of global vision. Tyry to ask your favourite vendor what do you need in order to be able to offer IPv4-L3VPN, IPv6-L3VPN and L2VPN (mainly point-to-point - NO MAC learning) over a backbone that does NOT use any single IPv4 address (backbone-side). Because you can do it on a backbone that does not use any single IPv*6* address, but you may want to go forwards, not backwards. Add a LNS in the mix (the v4 addresses for the LNS go in VRFs - that's not backbone). Add a money, rack space and power needed constraints in the mix. This exercise looks challenging with other vendors too, but with Cisco it's just impossible.

That's because it's not about l3vpn6 or l2vpn6; it's about IPv6. And you
can't business-case IPv6.

Some vendors fail to understand that IPv6 is not the money-maker. IPv6
is what attracts the customer to the network so that the money can flow.
It's a means to an end, not the end in itself.

> Of course, Cisco says there is no demand for one simple reason : the people talking with Cisco account managers (or whatever they are called) are only rarely those that care about technical stuff. They may want some features on the CPEs (like "ui uant SDWAN"), but for anything else (including backbone equipment) they only want lower prices. You end up with everybody having to deal with a specific platform in real life to dream about a specific feature, yet the vendor to consider that "nobody wants it".

One of the reasons I've never been keen on working for a vendor is
tunnel vision becomes easy. As an operator, you have a much wider view
of what's happening in the real world. When a vendor decides to home-in
on EoMPLS and VPLS being better signaled by LDP vs. BGP, you end up with
situations where they track user-demand through the number of TAC cases
the feature caused. The fewer the TAC cases, the lower the demand. Very

Nobody is going to demand LDPv6 because the over-arching problem is a
lack of IPv6 deployment at global scale. If folk don't deploy IPv6, they
will not think about LDPv6, RSVPv6, e.t.c. But to make it worse, if the
vendors keep encouraging the "big-spending" mobile operators to maintain
IPv4 by selling CGN licenses, it's kind of back-to-front, isn't it? No
operator unwilling to deploy IPv6 but favours CGN is ever going to ask a
vendor about LDPv6, especially if the vendor is in charge of building
and operating that backbone as a "professional, managed service".

Ultimately, we are not asking for an ASIC re-spin. We are not asking for
a doubling of forwarding capacity. We are not asking for a greener
chassis. We are not asking for 100Gbps ports. All of which are
physically impossible. We are asking for LDP to extended to support
IPv6. Really, how hard is that?


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