Hi Simon, This looks like an interesting project. What are you ultimately trying to achieve?
Stretching an Ethernet segment between sites shouldn't be the first choice, but I imagine you're having to deal with some legacy use case and your hands are tied. I'm a little curious on what that might look like. Best, Josh On Thu, Feb 9, 2023, 02:50 Simon Lockhart <si...@slimey.org> wrote: > All, > > I have a bit of a networking design challenge, and I thing EVPN is the > right > answer, but despite spending the last week reading loads of resources about > it, I can't quite get my head around one aspect. > > I'm trying to genericise the design a bit here, but what I've got is... > > I have multiple layer two broadcast domains that I need to link together > over a layer 3 network. The broadcast domains consist of multiple switches > carrying multiple vlans spanning multiple locations (think of it like a > customer campus network). > > I need to interconnect with each broadcast domain in two different > locations. > (so two PEs to two CEs), and link it back to a datacentre in another city. > > In the simple case, using EVPN, I see that I can run active-standby > multihoming, configuring one ESI for the customer campus network. If one > of my > PEs fails, or one of the customer CEs fails, then EVPN will fail over to > the > other link. > > However, the failure scenario I need to deal with is if a layer two link > fails > between two locations within the customer campus, the two halves of the now > split broadcast domain still need to be able to communicate with the > datacentre (but do not need to be able to communicate with each other). > > Every example I can see for EVPN shows multihoming to a single CE, and I > can't find anywhere an example which deals with a "split" ES. > > Is there a solution to this problem? > > Many thanks in advance, > > Simon >