3 Comments on “Which address is used by the Unicast Reverse Path Forwarding protocol to validate a packet against the routing”

1. Marek says:

   September 30, 2015 at 8:37 am

   When Unicast RPF is enabled on an interface, the router examines all packets received as input on that interface to make sure that the source address and source interface appear in the routing table and match the interface on which the packet was received. This “look backwards” ability is available only when Cisco express forwarding (CEF) is enabled on the router, because the lookup relies on the presence of the Forwarding Information Base (FIB). CEF generates the FIB as part of its operation.

   http://www.cisco.com/c/en/us/td/docs/ios/12_2/security/configuration/guide/fsecur_c/scfrpf.html

   
   
   
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2. Babar says:

   March 13, 2017 at 6:43 am

   Answer is: A*

   When a packet is received at the interface where Unicast RPF and ACLs have been configured, the following actions occur:

   Step 1 Input ACLs configured on the inbound interface are checked.

   Step 2 Unicast RPF checks to see if the packet has arrived on the best return path to the source, which it does by doing a reverse lookup in the FIB table.

   Step 3 CEF table (FIB) lookup is carried out for packet forwarding.

   Step 4 Output ACLs are checked on the outbound interface.

   Step 5 The packet is forwarded.

   http://www.cisco.com/c/en/us/td/docs/ios/12_2/security/configuration/guide/fsecur_c/scfrpf.html

   
   
   
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3. Julius Simpson says:

   November 6, 2017 at 2:06 am

   BTW, free of the new 489Q 300-101 dumps are available here FYI:

   https://drive.google.com/open?id=0B-ob6L_QjGLpZEE0S2YxR3ZMUWs

   Best Regards!

   
   
   
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