[rbridge] Ingress Rbridge address and BCN
sgai at nuovasystems.com
Sat Oct 28 08:28:32 PDT 2006
Today the largest layer 2 networks have 100,000 stations. This number is
still increasing and we may see 1 million stations. Using 256 port
switches, it requires 4,000 switches, to build a fat tree kind of
topology you need to multiply approximately by 2, so you are at 8,000.
16 bits works, but I am OK with the format proposed by Eric, i.e.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
| Egress | CoS | TTL |
| Ingress | Rerved |
IF the reserved bits can be used by the outcome of the ongoing FTAG
discussion (I still don't like the alignment :-).
Can we assume that we have agreed on the Ingress RBridge address, focus
on the FTAG and try to close?
> -----Original Message-----
> From: rbridge-bounces at postel.org [mailto:rbridge-bounces at postel.org]
> Behalf Of Radia Perlman
> Sent: Friday, October 27, 2006 11:21 AM
> To: Gray, Eric
> Cc: rbridge at postel.org
> Subject: Re: [rbridge] Ingress Rbridge address and BCN
> Summary of below---asking how many RBridges anyone would ever expect
> need in a single campus.
> Gray, Eric wrote:
> > I don't know where the idea that we only need a 2-byte
> >nick-name comes from. When did we change from the idea of using
> >an MPLS (or MPLS-like) SHIM with 19 bits to represent specific
> >RBridges to using a completely different SHIM and only requiring
> >16-bits of RBridge identification?
> The number 19-bits was chosen just because the MPLS label field was 20
> and we were stealing one to indicate whether the field was "ingress"
> There was no science behind 19-bits other than it happened to be
> seemed uncontroversially way more than we'd actually need, so would
> clearly be big enough.
> If we weren't using an MPLS-like header, then we can actually think
> what size field we'd need. We wouldn't want the nickname space to be
> too densely used, so 16 bits would support, say, 30,000 RBridges.
> So the question is---how many RBridges would anyone need? Remember,
> is for
> your "LAN"---it's not intended to replace layer 3. What size bridged
> are people building today? More than 1000 bridges?
> So if nobody is building anything more than 1000 bridges, say, then 16
> bits is
> safe. If 16 bits isn't safe, then sure, we can pick a different size
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