[j-nsp] Layer 2 ethernet redundancy?

[Tony Frank]

Hi,

On Thu, Jan 22, 2004 at 12:38:50PM +1100, Dmitri Kalintsev wrote:

> 1) Your M20 *is* a single point of failure, so I presume it has dual REs
> installed.
> 2) From the past experience, we have found that box redundancy *usually*
> makes sense when it is deployed in geographically diverse locations (i.e.
> different POPs, connected to compose a redundant topology). In cases of a
> single-location deployments, it makes more sense to deploy a single bigger
> box, but equip it with redundant everything. 6500 can be made fairly
> redundant - different 10/100(/1000) cards for connections to your M20,
> different 10/100(/1000) cards (maybe separate from previous ones) to connect
> to your customers.

Currently m20 is "very" redundant - dual re, ssb, dual PIC for downstream
separate dual PIC for upstream (all on separate FPC)

The entire setup is duplicated in another geographical location so if the m20
is down, traffic can reroute.

The specific concerns I guess are more to do with the practice of having the
two interfaces into separate switches carrying the same logical vlan.

eg other routers have only single interface, so it's simple to use the 
interface IP as the BGP neighbour address - if either interface or router
fails the path is gone (and BGP goes away)

On m20 we have two interfaces with two IP.
Currently we spread the BGP sessions across the two interface IP addresses.
Another point that was not mentioned originally is that each 'customer' has
two routers, one on each l2 switch.

As I mentioned, it works but I am keen on examples of how it is done elsewhere.

> I'm not sure if it is a good idea to run 803.2ad to two different boxes.

Some of us agree with that, others suggest "if it works, use it" :)

thanks for the feedback,

Tony