The show isis database Command

The show isis database command shows the LSPs held in the local database. The LSP ID shows the system ID of the generating router and whether this LSP is from a router or a pseudonode. The last octet shows whether the LSP was too large to fit into one PDU; a nonzero value in this field indicates that this is a fragment of an LSP. The number states the fragment number.

Because IS-IS is a link-state protocol, the database should be identical on every router of the same level within the area.

The EXEC command has the following syntax:

show isis area-tag database [level-1] [level-2] [11] [12] [detail] [lspid]

Table 12-5 explains the syntax of this command.

Table 12-5 Explanation of the show isis database Command

Field

Description

area-tag

Used primarily in multiarea Integrated IS-IS configurations. This is a name for an Integrated IS-IS routing process on a router. Each name must be unique to the process on the router. If an area tag is specified, output is limited to the specified area.

Required for multiarea Integrated IS-IS configuration. Optional for conventional Integrated IS-IS configuration.

level-1

(Optional) Displays the Integrated IS-IS link-state database for Level 1.

level-2

(Optional) Displays the Integrated IS-IS link-state database for Level 2.

11

(Optional) Abbreviation for level-1.

l2

(Optional) Abbreviation for level-2.

detail

(Optional) Shows the contents of each LSP rather than a summary display.

lspid

(Optional) Identifier for the link-state PDU. Shows the contents of the specified individual LSP.

Example 12-11 shows output for the show isis database command. Example 12-11 Output for the show isis database Command

RouterA#show isis database

IS-IS Level-1 Link State Database:

LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL

A.00-00 * 0x00000017 0X76D5 876 1/0/0

IS-IS Level-2 Link State Database:

LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL

A.00-00 * 0X00000018 0XB74F 881 0/0/0

0000.0000.000B.00-00 0X0000001A 0XB561 872 0/0/0

0000.0000.000B.01-00 0X00000016 0X6045 1095 0/0/0

Example 12-11 Output for the show isis database Command (Continued)

C.00-00 0X0000001E 0x6267 869 0/0/0

C.01-00 0X00000002 0XF25F 958 0/0/0

0000.0000.000E.00-00 0X00000018 0X010A 858 0/0/0

0000.0000.000D.00-00 0X0000001A 0X413C 985 0/0/0

0000.0000.000D.04-00 0X00000017 0XFCA0 1006 0/0/0

Table 12-6 explains the meaning of the fields in the output. Note that both Level 1 and Level 2 databases are shown because the router is running the default configuration of Level 1-2 routing. All the LSP information is contained in these databases, including the LSPs generated by the router itself. An asterisk marks these entries in the output.

Table 12-6 Explanation of the show isis database Command

Field

Description

LSPID

The LSPID indicates the transmitting router. The system ID is followed by two octets. If the first octet has a value greater than 0x00, this indicates that the ID is that of the pseudonode and the system ID is that of the DIS.

The last octet is the Fragment bit. If the value is 0x00, the entire LSP was carried in one LSP. If the value is greater than 0x00, it indicates that this PDU is the nth fragment of the LSP.

LSP Seq Num

Sequence number for the LSP. This allows routers to determine whether they have received the latest information from the source and ensures the integrity of the linkstate database.

LSP Checksum

Checksum of the entire LSP packet.

LSP Holdtime

Amount of time the LSP remains valid (in seconds). An LSP holdtime of 0 indicates that this LSP was purged and is being removed from the link-state database.

ATT

The LSP indicates that this router is a Level 2 router with a path out of the area. Level 1 routers use the presence of this bit to identify the closest Level 1-2 router to send their out-of-area data.

P

Partition repair capability. Not supported by Cisco.

OL

The Overload bit indicates that the router has an incomplete database because of memory overload and is therefore not used for transit data.

Was this article helpful?

+5 -5

Post a comment