[c-nsp] Cisco Nexus as MetroE switch?

[Adam Vitkovsky]

> From: Marian Ďurkovič [mailto:md at bts.sk]
> Sent: Wednesday, November 04, 2015 3:01 PM
>
> On Wed, Nov 04, 2015 at 11:04:46AM +0000, Adam Vitkovsky wrote:
> > Hmm maybe Huawei s doing something radically different.
>
> Their implementation follows RFC6325.
>
Ok so the underlying transport has to be IEEE 802.3 encapsulation.

> > But my understanding is that TRILL is using MAC in MAC encapsulation
> > just like PBB.
>
I'd like to correct myself here I was digging and actually the top-most/hop-by-hop header (the "in MAC" piece) doesn't really need to be MAC and it can actually be PPP/IP/MPLS/whatever, although only MAC is standardized


> Well, there must be two MAC headers if you want to transport ethernet
> packet inside a container over ethernet network, but similarities with PBB
> end here.
> TRILL introduces its own header with similar information like IP header
> (source/destination addresses, TTL, various flags, maybe options).
> Although TRILL header is smaller and optimized for fast ASICs (for example
> addresses have only 2 bytes to allow faster lookups), TRILL switches *route*
> packets the same way as IP routers do - each hop has its own routing table
> (created dynamically by IS-IS) and makes independent decisions about next
> hop for each packet (with per-flow loadsharing over multiple equal-cost
> paths).
> They also decrement TTL and change outer MAC addresses on each hop,
> perform RPF check for multicast frames etc.
>
>
Ok I see what you mean I just got confused by your earlier statements " TRILL *is* internally using L3 backbone to transport ethernet packets" and " TRILL container is basicaly optimised IP container" and immediately I assumed IP addresses and IP backbone as the underlying transport which was a mistake on my part.

But yes I agree that routing or ISIS for that matter is L3 and the TRILL header has L3 properties although I would not call it IP container (maybe OSI Network Layer header just like CLNS/CLNP is).


adam




        Adam Vitkovsky
        IP Engineer

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