Hello, I have read that when an "Aggregate" label shows up in the LFIB, the LSR must remove the label and do an IP lookup to determine how to forward the packet. The only scenario for which I can seem to create this is in an MPLS VPN. I have also read that when you perform route summarization, you may see an "Aggregate" label, however I cannot produce these results. (From MPLS Fundamentals, p131 "Aggregate labels can be the result of aggregation or summarization of IP prefixes in the network.")
Here is the scenario I am testing: R3---R1---R2---R4---R5 R2 is the ABR performing summarization for two loopbacks on R5 (150.100.0.5/32, 150.100.1.5/32). Summary is 150.100.0.0/16. Notice that R2 still has both labels, there is no "Aggregate"...and it advertises an implicit null to R1. R2#sho mpls forwarding-table Local Outgoing Prefix Bytes tag Outgoing Next Hop tag tag or VC or Tunnel Id switched interface 16 Pop tag 10.1.1.1/32 0 Se1/1 point2point 17 Pop tag 192.168.13.0/24 0 Se1/1 point2point 18 18 10.1.1.3/32 0 Se1/1 point2point 20 Pop tag 10.1.1.4/32 0 Se1/0 point2point 21 Pop tag 150.100.45.0/24 0 Se1/0 point2point 22 21 150.100.1.5/32 0 Se1/0 point2point 23 22 150.100.0.5/32 0 Se1/0 point2point 25 23 10.1.1.5/32 0 Se1/0 point2point R1#sho mpls forwarding-table Local Outgoing Prefix Bytes tag Outgoing Next Hop tag tag or VC or Tunnel Id switched interface 16 Pop tag 192.168.24.0/24 0 Se1/0 point2point 17 Pop tag 10.1.1.2/32 0 Se1/0 point2point 18 Pop tag 10.1.1.3/32 0 Se1/1 point2point 19 Pop tag 150.100.0.0/16 0 Se1/0 point2point 20 20 10.1.1.4/32 0 Se1/0 point2point 25 25 10.1.1.5/32 0 Se1/0 point2point Now this seems all fine to me, R2 must do an IP lookup when it receives the unlabeled packets, and then it labels them before forwarding them. Why doesn't the output on R2 show "Aggregate"? Am I misunderstanding the use of "Aggregate"? Thanks, -- Bryan Bartik CCIE #23707 (R&S), CCNP Sr. Support Engineer - IPexpert, Inc. URL: http://www.IPexpert.com
