LDPv6 Census Check

Radu-Adrian Feurdean nanog at radu-adrian.feurdean.net
Thu Jun 11 07:56:56 UTC 2020

On Wed, Jun 10, 2020, at 20:51, Mark Tinka wrote:
> Well, according to them, SRv6 is winning customers over, and nobody
> wants LDPv6. Then again, they have LDPv6 in IOS XR; figures.

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

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.

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.

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".

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