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Community Member

ISIS LSP-ID or router-ID -- Originating RID


Would like your assistance please for below

I know for ISIS there is no concept of router-ID however when you check routing table it gives you the IP address of originating router-ID  .. Now the question what is this IP address and how could we change it ?


R1#show ip route
Routing entry for
  Known via "isis", distance 115, metric 168, type inter area
  Redistributing via isis 1
  Last update from on FastEthernet0/0, 00:03:02 ago
  Routing Descriptor Blocks:
  *, from, 00:03:02 ago, via FastEthernet0/0
      Route metric is 168, traffic share count is 1


R3#show isis database R3.00-00 detail

IS-IS Level-1 LSP R3.00-00
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime      ATT/P/OL
R3.00-00            * 0x00000022   0xA97A        718               1/0/0
  Area Address: 49.1234
  NLPID:        0xCC
  Hostname: R3
  IP Address:                      <<<----------
  Metric: 10         IP
  Metric: 0          IP
  Metric: 10         IS R3.01
  Metric: 148        IP-Interarea




Sherif Ismail

Cisco Employee

Hi Sherif,Its been a long

Hi Sherif,

Its been a long time digging the TLVs :).  IIH and LSP will carry "IP Interface Address" (code point 132) which in turn carries the IP address. In case of IIH, it carries the interface address and in LSP, it carries the lowest address with /32 subnet (If my memory serves me right).



Community Member

Hi NagendraThanks for your

Hi Nagendra

Thanks for your reply ... Is there a way to manually change it  as we need to have a common planned IP address in "show ip route" ?

Many Thanks

Cisco Employee

Hi Sherif,Since this is only

Hi Sherif,

Since this is only for informational purpose, I think it cannot be manually controlled. I dont remember seeing any CLI to change the same.

Since it prefers /32 loopback address, it should give you some control by cinfiguring /32 management address. 



Community Member

Hi NagendraSomehow :)  Issue

Hi Nagendra

Somehow :)  

Issue as you may expect there are several loopbacks configured so not always the management loopback is the one chosen by ISIS.

Not a big issue I know but it just facilitates troubleshooting 


Sherif Ismail

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