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Help with Unicast Reverse Packet Forwarding (uRFP)

I'm trying to implement some sort of anti spoofing measure on my router (Cisco 806 DSL router) and was reading about uRFP. From what i understand you can use this in place of applying ingress and egress ACLs on the interfaces connecting to external networks. I applied this on my dialer interface and after this I was unable to browse the web at all. I disabled uRFP and was back to normal.

I read uRFP can have problems with asymetrical routing and will discard packets incorrectly. From what i understand asymetrical routing is where the packet does not take the same path from A to B than from B to A, if this is the case, could this be the case why I have no internet connection when I enable it on the dialer interface? Is my only choice then to use ACLs on the interface?

Thanks

Louis

1 REPLY
Bronze

Re: Help with Unicast Reverse Packet Forwarding (uRFP)

Be sure that CEF is enabled on your router (Unicast RPF relies on the FIB table generated by CEF). If that doesn't help, take a look through the following link which has some troubleshooting tips:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fsecur_c/fothersf/scfrpf.htm

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