Have two sites with Cisco 2520 grid switches connected over fibre (OPGW, to be precise).
- Site #1 is the existing site, with a 2520 connected to Site #2 (via fibre). There is an existing 3G backup connection elsewhere in that network (via a 1900 + 3G WIC).
- Site #2 is the new site, solely 2520 switches, and needs a backup 3G connection.
The current plan is to connect a 3G router (i.e. Sierra Raven XE) to a second port on the Site #2 edge switch that terminates the OPGW fibre. Ideally, if there's a comms failure on the Site #2 switch FE0/1 port connected to the OPGW (i.e. damage, contractor bumps a FOBOT, etc) the switch should pick up on this and fail over to the 3G router sitting on FE0/2.
My understanding is that setting up an IP SLA on the Site #2 edge switch that hits (via
icmp-echo) an IP within Site #1 is the 'simplest' approach here.
Site #2 edge switch:
ip sla 1
ip sla schedule 1 life forever start-time now
track 1 ip sla reachability
ip route 0.0.0.0 0.0.0.0 192.168.x.x track 1
ip route 0.0.0.0 0.0.0.0 FastEthernet0/2 20
! metric of 20 to ensure it only kicks in when track 1 fails
Site #1 edge switch stays 'as is'.
Have I missed anything here? Can we do this purely with IP switches?