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%CLNS-3-BADPACKET: ISIS: LAN L1 hello, Duplicate system ID

We get an error "%CLNS-3-BADPACKET: ISIS: LAN L1 hello, Duplicate system ID" on each of our 2 6500 switches running ISIS.  The system ID's have been checked and are fine.  A 802.1q trunk connects the two switches.  We get the error every 60 seconds for 7-8 minutes in a row about every 2-3 hours.

There is no information on this error on Cisco's website.  MTU size is fine on each switch.
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davidhvoss
Asked:
davidhvoss
1 Solution
 
JFrederick29Commented:
It means that one of your Level 1 routers have the same system ID in their SNPA address.  You are sure the system ID portion of the NET is not the same on both routers?  You don't have any other devices running IS-IS on your network?

Router 1:

router isis
net 49.0001.0000.0c12.3456.00  <---0000.0c12.3456 portion needs to be unique.

Router 2:

router isis
net 49.0001.0000.0c12.3457.00  <---0000.0c12.3457 portion needs to be unique.
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