The DISPLAY TCPIP,<tcpipjobname>,OMPROUTE,OSPF,EXTERNAL command lists the AS external advertisements belonging to the OSPF routing domain. One line is printed for each advertisement. Each advertisement is defined by the following three parameters:
Its link state type (always five for AS external advertisements), its link state ID (called the LS destination), and the advertising router (called the LS originator).
A sample output with an explanation of entries follows:
EZZ7853I AREA LINK STATE DATABASE 269
TYPE LS DESTINATION LS ORIGINATOR SEQNO AGE XSUM
5 @9.67.100.0 9.67.100.8 0x80000001 4 0X408
5 @9.169.100.0 9.67.100.8 0x80000001 4 0X73E
5 @9.169.100.14 9.67.100.8 0x80000001 4 0XE66
5 @192.8.8.0 9.67.100.8 0x80000001 4 0XAAF
5 @192.8.8.8 9.67.100.8 0x80000001 4 0X5A4
# ADVERTISEMENTS: 5
CHECKSUM TOTAL: 0X 2A026
The fields for this output are:
TYPE |
Always 5 for AS external advertisements. |
LS DESTINATION |
Indicates an IP network/subnet number. These network numbers belong to other Autonomous Systems. |
LS ORIGINATOR |
Indicates the router that originated the advertisement. |
SEQNO, AGE, and XSUM |
It is possible for several instances of an advertisement to be present in the OSPF routing domain at any one time. However, only the most recent instance is kept in the OSPF link state database (and printed by this command). The LS sequence number (Seqno), LS age (Age), and LS checksum (Xsum) fields are compared to see which instance is most recent. The LS age field is expressed in seconds. Its maximum value is 3600. |
At the end of the display, the total number of AS external advertisements is printed, along with a checksum total over all of their contents. The checksum total is simply the 32-bit sum (carries discarded) of the individual advertisement LS checksum fields. This information is used to quickly determine whether two OSPF routers have synchronized databases.
See also: