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ISIS Routing Error Message

Hi All,

          Can someone please help me out with what the below error message means and how to get rid of it.

%CLNS-3-BADPACKET: ISIS: LAN L1 hello, bad circuit type 0 from ca01.1320.0038 (GigabitEthernet3/0)

Without any debugging on, some of my routers kept generating these messages, even though it does have any effect on my routing process.

I have googled and do a lot of search on Cisco's site but to no avail. Please no more Cisco links, just explain if you know.

Thanking you all in advance,


Ivan Krimmel
Rising star

Hi O.A.,

the message says that a HELLO packet contains a reserved circuit type equal to zero, while the system was expecting to get type 1 or 2 or 1/2. If you are running some sort of an emulator, then it is a known glitch which you might rectify by simply having the instances restarted. If this is a real gear, you might do a interface reset. You also could set up a sniffer capture and dig it a bit further. From troubleshooting point of view worth of interest is to check the full log on the node you're seeing these messages, as well as to check its peer on gig3/0(ca01.1320.0038).


Hi, I do not understand "the instances restarted" part, what do you mean by instances? (Interface? isis process? or line card?) I tried to reboot the GNS box, but still getting same ISIS error messages.

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