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ip reverse path


i recently configure my cisco pix to handle 2 isps. 2 outside insteface with security 0 and 1. both outside interfaces are belongs with two seperate network. inorder this setup to work i had to disable "ip reverse path" is it safe to keep this disable ? if no , is there any alternative method to configure two isps on one pix. so if one fails the traffic will go through the other one.



Re: ip reverse path

The Unicast Reverse Path Forwarding feature checks to see if any packet received at a router interface arrives on one of the best return paths to the source of the packet. The feature does this by doing a reverse lookup in the CEF table. If Unicast RPF does not find a reverse path for the packet, Unicast RPF can drop or forward the packet, depending on whether an ACL is specified in the Unicast Reverse Path Forwarding command. If an ACL is specified in the command, then when (and only when) a packet fails the Unicast RPF check, the ACL is checked to see if the packet should be dropped (using a deny statement in the ACL) or forwarded (using a permit statement in the ACL). Whether a packet is dropped or forwarded, the packet is counted in the global IP traffic statistics for Unicast RPF drops and in the interface statistics for Unicast RPF.

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