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Where did these tunnel interfaces come from?!?

j_saarikko
Level 1
Level 1

Hello,

 

just wondering why one of our routers creates tunnel interfaces dynamically.

 

I was setting up a GRE tunnel to transport multicast traffic over network. After I was done, I found two extra tunnel interfaces with command show ip interfaces brief and those extra interfaces uses my original tunnel interface as their IP addresses. There is no any configuration regarding to these extra interfaces in running config. How did this happen? Any explanations? Is it relating somehow to my multicast solution?

If I got two dynamically created tunnels does that mean that I have at least two concurrent multicast groups on my router in active state?

Sorry for dummy questions but I have almost zero experience what comes for multicast and last time I studied it in school about 8 year ago...

-JJ

1 Reply 1

Jose Jara
Level 3
Level 3

Hi,

These are created dynamically, one to encapsulate multicast packets and the other one to decapsulate. You can see them with the command < show ip pim tunnel > . You can find the description and purpose of these tunnels here:

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti/command/imc-cr-book/imc_s1.html#wp9533023710

Hope this helps,

Jose.

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