l2tp tunnels

Unanswered Question
Jan 18th, 2010

I have a Cisco 7200 router configured as an LNS in which they must complete a high number of L2TP tunnels.

It seems very strange that the ouput of the command "sh ip int brief", the virtual-Template appears down-down, even when I'm 35 tunnels on state "established" and are assigned Virtual-Interface

Virtual-Template212        xx.xxx.x.xxx    YES TFTP   down                  down

Another problem I encounter is that it assigns the same Virtual-Interface for different circuits. Is this normal?

23488      1201       9891       [email protected], Vi2.3 est    19:30:55 950

23504      2469       45432      [email protected], Vi2.3 est    14:24:10 271

Any idea what is happening?

This is the configuration of the Virtual Template:

interface Virtual-Template212

mtu 1501

ip unnumbered Loopback1

no ip redirects

no ip unreachables

ip mtu 1460

ip tcp adjust-mss 1420

no peer default ip address

ppp max-bad-auth 10

ppp authentication chap vpdn

Thanks for your help

I have this problem too.
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Giuseppe Larosa Mon, 01/18/2010 - 13:41

Hello Juan,

my first impressions are:

1) normal virtual-template is used to clone, derivate the virtual-access interfaces. Virtual-access interfaces when up/up belong to active sessions

virtual-template interface can be down/down I think I've seen this.

2) it may be a way to provide scalability to overcome the problem of IDB limitations, it may be a feature and not a problem

see for example the following document to find commands to check L2TP state


Hope to help


emilio1973 Thu, 01/21/2010 - 07:20

I saw that my router has no problem So I'll start to think it is a problem from the supplier or the CPE.

Thanks for your help


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