Re: [Rift] comments on draft-head-rift-auto-evpn-00

[Antoni Przygienda <[e-mail]>]

Hey Sandy, yes, all sessions come up automatically

Yes, all the data is derived automatically just from the today’s RIFT database on the leaf or ToF (no key value necessary or any new TIEs, just topology info we have today already)

There is _NO_ information about ToF in the leaves, e’thing is scaling just like RIFT does today

KV 😉 will be just optional for telemetry in case that’s desired & will flow northbound only so no change in scaling properties.

In short:

RR elects itself RR or not in the plane (section 6.3.2.1) and based on that  assumes a special RR loopback with last byte representing its preference

X::[pref]

Every leaf tries to connect to

X::1
X::2
X::3

Which they know are RRs (# of RRs doesn’t matter, just pick a reasonable constant)

Each leaf elects own loopback in a well known range

Y/64 :: something

On each RR any connection attempt from Y/64:: something is accepted (pretty much all mature implemenations today support that). If you want to be fastidious you could actually on the ToF that is RR (since it sees all node N-TIEs) even specify each leaf as allowed peer

All took a bit to figure out and my first input to the idea when brought to me was “well, of course it’s impossible to ZTP EVPN, even with RIFT” 😉 But, with enough grey matter grease it actually works pretty well from all we see …

It will all become more concrete when we flesh the algorithm appendix albeit the description today already gives a pretty good idea but without standardized algorithms for the distributed elections interoperability cannot be guaranteed …

--- tony

From: "[e-mail]" <[e-mail]>
Date: Wednesday, 10 March 2021 at 16:31
To: Antoni Przygienda <[e-mail]>, Jordan Head <[e-mail]>, Wen Lin <[e-mail]>
Cc: "[e-mail]" <[e-mail]>
Subject: [Rift] comments on draft-head-rift-auto-evpn-00

[External Email. Be cautious of content]


Hi Tony, co-author,

Thank for your presentation in RIFT and BESS WG.

I have question about the intent of this draft, before I read more on the detail. :-P

From the draft, seems like the leaf node will build BGP connection automatically, and exchange the necessary MAC/IP through EVPN advertisement.

But does the info on leaf for BGP building (AS, router-id, etc.) derived from the leaf node itself? If it is, the BGP auto discovery function is included in (That is also the confusion from BESS WG).

If the info for BGP building on leaf comes from the TOF nodes (RR), then it has no relationship with BGP auto discovery, IMO necessary sourcebound KVs are needed. But I am not sure because I have not seen explicit description in the draft.

Best regards,

Sandy






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