What is RPF check in Asa?

What is RPF check in Asa?

The ASA will examine the source address of the spoofed inbound packet and will see that source IP 192.168. A packet with such a source IP should never arrive from the outside interface. Therefore the packet will be dropped. The ASA performs the RPF check by using its routing table.

What is RPF check in multicast?

The process of checking the forwarding path based on the source address is a reverse path forwarding (RPF) check. When a router receives a multicast packet, it searches the unicast routing table for the route to the source address of the packet.

What is Cisco NSF?

Cisco Nonstop Forwarding (NSF) with Stateful Switchover (SSO) provides increased network service availability and protection against unplanned downtime due to hardware or software problems. Cisco NSF/SSO evolved from a series of progressive enhancements to reduce the impact of specific network outages.

What is ip verify reverse path interface?

The ip verify reverse-path command is a security feature that does a route lookup based on the source address. This is why it is called reverse path forwarding. With this command enabled, packets are dropped if no route is found for the packet or the route found does not match the interface on which the packet arrived.

What is RPF check in PIM?

RPF checks are performed only on unicast addresses to find the upstream interface for the multicast source or RP. The routing table used for RPF checks can be the same routing table used to forward unicast IP packets, or it can be a separate routing table used only for multicast RPF checks.

What is deny TCP reverse-path check?

Event 106021 is generated when a packet that does not have a source address represented by a route is discarded by unicast RPF, which would have been enabled with ‘IP verify reverse-path’ command. …

How do you test uRPF?

To test that our uRPF is working, we are going to go to our Customer Router and set up a “fake” address on a Loopback interface. If the traceroute doesn’t work, did you remember to remove the trigger routes at the end of the uRPF lab? Check on the Trigger Router to make sure you did this.

How do I enable unicast RPF for Cisco Express Forwarding?

An important consideration for deployment is that Cisco Express Forwarding switching must be enabled for Unicast RPF to function. This command has been enabled by default as of IOS version 12.2. If it is not enabled, administrators can enable it with the following global configuration command: ip cef

Is it possible to use unicast RPF in VRF mode?

Unicast RPF in VRF mode will not be covered in this document. When administrators use Unicast RPF in strict mode, the packet must be received on the interface that the router would use to forward the return packet.

What are the requirements for deployment of unicast RPF?

An important consideration for deployment is that Cisco Express Forwarding switching must be enabled for Unicast RPF to function. This command has been enabled by default as of IOS version 12.2.

Why does unicast RPF drop legitimate traffic?

Unicast RPF configured in strict mode may drop legitimate traffic that is received on an interface that was not the router’s choice for sending return traffic. Dropping this legitimate traffic could occur when asymmetric routing paths are present in the network.