How about the source IP? RIP v1 is sent to 255.255.255.255 broadcast. RIPv2 is sent to 224.0.0.9 multicast. Both are local-link only, so won't go THROUGH a router. The sending source IP will tell you where they came from. If you're using VLANs (trunks), there won't be any issues. If you're using secondary addresses, this will depend on whose devices you use. In the Cisco world, packets will always be sourced from the primary IP address on an interface. And if the receiving router doesn't have a subnet matching the sender, packets/updates are ignored. (Again, Cisco world you can use "no validate-update-source" to override this check) But that gives you a tracking method on packets. Scott -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Tom Sanders Sent: Sunday, August 21, 2005 12:13 PM To: nanog@nanog.org Subject: Rip again! Hi, There isnt IMO a way in RIP to identify the source of the RIP packet (the way we have Router ID in OSPF, system ID in ISIS, etc.) Now assume we have 2 vlans defined on an ethernet. Thus we would have two IP interfaces, 1.1.1.1/24 and 2.2.2.2/24 and both using the same physical interface. RIP is running on both these interfaces. My doubt is that how will another router, which is configured in the same way (2 vlans) be able to differentiate between the RIP responses originated by 1.1.1.1 and 2.2.2.2? Thanks, Toms