[rbridge] it's time to summarize things

[Stewart Bryant]

Radia Perlman wrote:

> I think I might need a picture of what you're saying, but I think it's 
> just the
> opposite. RBridges can path split, just like routers can, whereas if the
> spanning tree turns off one of the links, then a bridge would only use 
> one of
> the paths.

The SPT situation is as follows:

     +----+
-----|    |    L1
-----| B1 |---------->To core
-----|    |
     +----+
        |
        | L3
        |
     +----+
-----|    |    L2
-----| B2 |---------->To core
-----|    |
     +----+

You want
B1 to connect a bunch of systems to the main network via L1
B2 to connect a different bunch of systems to the main network via L2

So you set B1 and B2 with low priority, so the root is to the
right in the main network, and the ports connecting B1 and B2 to L3
go into blocking.

Say most of the traffic is to some server S. This traffic will
be load balanced over both links L1 and L2.

Now replace the core with an Rbridge network, but leave B1 and B2
running SPT (because you can't upgrade the wiring closets - there are
too many of them)

How does the traffic from B1 and B2 to S get load balanced
via L1 and L2?

- Stewart