Hi Guys I think I have the reason for the behavior in my lab. I have the 'silent host' issue which happens in labs but generally doesn't happen in live networks. For my host devices I used Cisco routers with an IP address on a single interface, all these devices were doing is a ping and and ARP to a single IP address. In a production network these hosts would be workstations and servers and would be a lot more chatty, generating broadcast traffic. When I drop the CSR1 site 1 WAN overlay the remote Cisco host does not generate any new broadcast traffic, new broadcast traffic would flood from the CSR1 site 2 across the overlay and eventually into the 'customer' layer 2 at site 1.
So in summary, in a production network the hosts would generate enough broadcast traffic to keep failover connectivity issues to a minimum. In a lab with silent hosts, you will have to wait 5 minutes for the 'customer' layer 2 mac address table to age out before connectivity is restored. For info I used Cisco routers as end hosts because they were easy, quick and lightweight to spin up. I still don't fully understand why the OTV host doesn't generate a TCN as documented so if anyone could get an answer on that it would be great. For now I am happy to design OTV into my customer solution. Thanks Rick On 26 January 2018 at 15:23, Richard Clayton <sledge...@gmail.com> wrote: > Hi Guys > > I have configured Multihomed OTV in a virtual lab on EVE-NG using Cisco > CSR's. The lab is 2 x CSR at one site both connected to layer2 switch and > a single CSR at a remote site. > Everything works good apart from one thing. At the dual router site, when > I drop the OTV WAN/Overlay interface on the active CSR R1, the remote mac > appears in the R2 bridge-domain (as it should) but the 'customer' layer 2 > switch mac address table still show the mac address as facing the R1 LAN. > After 5 minutes the mac table times out and traffic is then restored over > the R2 path. > Is there any way R2 can update the customer L2 switch when the remote mac > moves over to it to make the failover quicker? > I did read a Cisco article that said if spanning tree is enabled on the > OTV router, it will send out a TCN which will update the L2, I have > spanning tree enabled on the OTV routers but when I drop the OTV > WAN/Overlay interface, it does not send out a TCN, I had wireshark running. > > Thanks > Rick > > > -- > If you try to reinvent the wheel you will end up with something non-round > and should expect an uncomfortable ride. The wheel has no copyright. > Richard Clayton - 17/11/2014. > -- If you try to reinvent the wheel you will end up with something non-round and should expect an uncomfortable ride. The wheel has no copyright. Richard Clayton - 17/11/2014. _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/