tailieunhanh - The Complete IS-IS Routing Protocol- P36

The Complete IS-IS Routing Protocol- P36: 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. | 350 13. IS-IS Extensions hannes@Frankfurt show isis database extensive . TLVs Area address 3 Speaks IP IPv6 IP router id IP address Hostname Stockholm IS neighbor Metric 1 IP address . IOS command output London show isis database verbose IS-IS Level-2 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT P OL . 0x00000040 0xD323 491 0 0 0 Area Address NLPID 0x81 IS neighbor Metric 63 . The LSP shown in the IOS command output does not contain the Hostname TLV. As it does not list any IP-related TLVs it may be that this is a CLNS-only router that is probably running older software that does not support the Hostname TLV. If the hostnames made their way into the hostname cache then all IS-IS occurrences of the System-ID are replaced using their respective name. See Table for how Pennsauken s System Node and LSP-IDs are represented using the new name resolution service. Today IS-IS is one of the most convenient routing protocols. It aids the network engineer and troubleshooter by offering a kind of distributed name service. All of the IS-IS-related display functions like displaying adjacencies examining the link-state database or logging functions make use of a System-ID to hostname translation cache and display System-IDs Node-IDs and LSP-IDs with their name rather than their hexadecimal representation. The next extension to IS-IS will cover the authentication scheme of LSPs and their implementation. Authenticating Routing Information 351 Authenticating Routing Information Authenticating routing protocol messages is a basic building block for every network security strategy. Some people argue that authentication is pushing the envelope for IS-IS since all the messages run natively on Layer 2 which means that the protocol cannot be exposed to a remote attack from the Internet because there is simply no possibility for .