tailieunhanh - The Complete IS-IS Routing Protocol- Part 18

The Complete IS-IS Routing Protocol- P18: 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. | LSPs and Revision Control 157 Figure . The overloaded routers local prefixes are still reachable while transit-traffic is kept away You can examine the contents of the Attribute block by issuing a show isis database. This command is supported on both IOS and JUNOS routers as shown in the following IOS command output Amsterdam show isis database . IS-IS Level-1 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT P OL 158 6. Generating Flooding and Ageing LSPs r i 0x00002fac 0xC24F 60128 1 0 0 IS-IS Level-2 Link State Database LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT P OL 0x00000128 0xB8EF 36163 0 0 1 0x00000128 0x455A 42001 0 0 0 0x00000123 0xEFC1 5023 0 0 0 . In JUNOS you can get a quick overview of the status of some of the bits by issuing the show isis database command. If you want to see the Attribute block for one LSP specifically then you can request a specific LSP s extensive output by issuing a show isis LSP extensive. There are various levels of output for the show isis database command. You can see the default and how the extensive modifier changes the output in the following JUNOS command output hannes@New-York show isis database IS-IS level 1 link-state database LSP ID Sequence Checksum Lifetime Attributes 0x2fac 0xc24f 62063 L1 Attached . 4 LSPs IS-IS level 2 link-state database LSP ID Sequence Checksum Lifetime Attributes 0x128 0xb8ef 36063 L1 L2 Overload 0x128 0x455a 41901 L1 L2 0x123 0xefc1 4922 L1 L2 . 12 LSPs hannes@New-York show isis database LINX-gw extensive Sequence 0x128 Checksum 0xb8ef Lifetime 36063 secs IS neighbor Metric 2000 IP prefix 32 Metric 0 Internal IP prefix 28 Metric 2000 Internal . Packet LSP id Length 98 bytes Lifetime 36063 secs Checksum 0xb8ef Sequence 0x128 Attributes 0x7 L1 L2 Overload NLPID 0x83 Fixed length 27 bytes Version