tailieunhanh - The Complete IS-IS Routing Protocol- P44

The Complete IS-IS Routing Protocol- P44: IS-IS has always been my favourite Interior Gateway Protocol. Its elegant simplicity, its well-structured data formats, its flexibility and easy extensibility are all appealing – IS-IS epitomizes link-state routing. Whether for this reason or others, IS-IS is the IGP of choice in some of the world’s largest networks. | LDP over RSVP-TE Tunnelling 431 LDP session are now associated with the TE tunnel and then used for traffic forwarding. When Paris advertises a label back to its local POP routers then a SWAP PUSH state on the forwarding plane is generated. The label of the TE tunnel is PUSHed as top level label and the label learned via the multi-hop LDP session is the SWAPed label. The edge routers send their traffic down the LDP established paths and do not even know that their traffic is being engineered in the core topology. As soon as the traffic arrives at the ingress of the TE tunnel Paris an additional label is PUSHed on top of the label stack and the traffic is sent down the TE tunnel. The penultimate TE tunnel router New York removes the top label and the LDP label underneath becomes visible and is used for further relaying traffic towards the LDP egress router. Configuration of LDP over RSVP-TE tunnelling is done using the mpls ldp neighbor address targeted Idpkeyword in IOS and the Idp-tunneling keyword in JUNOS. IOS configuration In IOS LDP tunnelling is a global option which can be configured using the mpls ldp neighbor address targeted statement. London show running-config . mpls ldp neighbor targeted ldp . If the multi-hop LDP session comes up and there is an RSVP-TE tunnel to this destination then the resolver will automatically set up the SWAP PUSH state. In JUNOS LDP over RSVP-TE tunnelling is a property of the TE tunnel and is configured under the protocols mpls label-switched-path name stanza. JUNOS configuration In JUNOS the ldp-tunneling keyword automatically sets up a session between two ends of a TE tunnel. edit hannes@Frankfurt show . protocols mpls label-switched-path to-London to ldp-tunneling interface so-1 2 0 interface . 432 14. Traffic Engineering and MPLS It is imperative that the loopback interface or interface all is listed when configuring LDP tunnelling. LDP multi-hop sessions are sourced using the IP address