Tunnel Interface Questions

[mbaker33]

Hello,

I have two remote offices that I am currently replacing P2P links in and upon review of the routers in the main and remote offices, I noticed that there are tunnel interfaces configured to route via a Loopback interface.  These older circuits are DS3 lines, and the new circuit is a fibre link that is basically metro ethernet between the sites.  My question is, what is the purpose of the tunnel interfaces?  I don't see any crypto lines to enforce encryption or anything like that, the only reason I can see for them would be for QoS reasons since our VoIP system does span the WAN links.  Any input would be appreciated. 

The first office I cut over I used a simple subinterface with Vlan tagging, since that is now the fibre circuit is supposed to work and the line came up fine.  I'm just affraid I am over looking something.  I am good with firewalls and switches, but I don't touch routers every day, so I am looking for a sanity check basically.

Thanks,

Mark

[Peter Paluch]

Mark,

Would it be possible to post the configuration of the two routers? It would help us in understanding what the Tunnel interfaces could have been used for.

Best regards,

Peter

[Joseph W. Doherty]

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Posting

As Peter notes, configs might help.  Some reasons for running tunnels include conveying site-to-site routing info or site-to-site multicast.