The need for a dynamic routing protocol on the Rhodes network is becoming apparent. At the moment, we've set up a bunch of static routes between our two Nortel Ethernet Routing Switch (neé Passport) 8600s, the Internet firewalls and the ResNet firewall. Next year, though, we'll be adding a third 8600 and a second ResNet firewall to the mix. The ResNet firewalls, in particular, will complicate matters as each will have about 20 not-very-aggregatable networks behind them....

Based on Guy's experience with the GINX BGP setup, we reckoned we'd setup IBGP rather than trying to get our heads around another routing protocol (such as OSPF, which we considered).

Guy's first tests with the 8600's BGP implementation weren't very fruitful: it flatly refused to advertise any networks to its peers. Now that we've upgraded the software on the 8600s, I've had another go at it, with much more success. So far, we've got two 8600s, an old Cisco 7200 and zebra on FreeBSD peering.

We're not as concerned about achieving reliability as ease of configuration. We're hoping that Nortel's SMLT/RSMLT implementation will provide us with a resiliant, triangular-shaped backbone segment, which will elegantly solve the reliability issues at layer 2 rather than layer 3.

Our intended BGP design tries to maintain our fairly flat routing structure: all routers will have an interface on the backbone subnet, and create a full IBGP mesh on that subnet. Full mesh should be easy enough to manage, because we should only need one peer group and n neighbour statements in each router. If that proves too painful, we could use the 8600s as route reflectors, with a full mesh between them.