L2TP max numbers of tunnels and sessions

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Sep 29th, 2008
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hope this is relevant for this forum..

There is some information about max L2TP tunnels and sessions here: http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6549/ps6587/prod_white_paper0900aecd8066d3f5.html

But in table 1 there is a note: "Numbers in the table are based on one session per L2TP tunnel"

Does this mean that with 1 tunnel we can have 1199 sessions kai with e.g. 10 tunnels 119 sessions per tunnel (suppose equal distribution)?

What about other models like 7200 and 7300 are you aware of any specs? (couldn't find them in cisco site)..

Thanks in advance,


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mpthimios Mon, 09/29/2008 - 02:26
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Thanks! but what is your definition of L2TP connection? Tunnel + Session?

Creating a tunnel results to one less session?

To make it more clear, cisco means e.g. up to 1200 tunnels and up to 1200 sessions?

If this is the case then max 1200 sessions can be distributed to max 1200 tunnels..

Thanks again,



In relation to the topic - I class a tunnel as a session. A connection between a client and the router using the L2TP protocol.

What you put over that tunnel/session is irrelevant. The table indicates the MAX number of terminated L2TP connections on the device.

So if you have 50 remote users using L2TP - you would have 50 tunnels/sessions. But each one of those users, could have email/server SMB connections internal WEB connections that TRAVERSE the L2TP tunnel/session.


mpthimios Mon, 09/29/2008 - 02:51
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I see your point!

But a LAC can create one tunnel and have many sessions running within the tunnel where each session serves one user.

I agree that over each session users can have connections like email/internal web etc.

If we consider this model one tunnel can support the 50 sessions you mention in the example, which means that it is not necessary to create 50 tunnels.. (or is it?).. And this creates some confusion in cisco limitations...

Wikipedia has a nice callflow: http://en.wikipedia.org/wiki/L2tp

That's how my question was triggered..

Thanks for the interesting discussion,


Sorry I am confused - what is the question now?

You can have many "sessions" within the tunnel - but they are from end point to enpoint?

Your orginal question was "L2TP max numbers of tunnels and sessions" - a tunnel is a session at layer 5 to layer 1.

What pass "over" or "in" the tunnel is irrelevant. The table you suipplied with the inital post states the MAX amount of sessions, tunnels, L2TP connections the device can handle.

mpthimios Mon, 09/29/2008 - 07:30
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the question is the same.

A tunnel is a prerequisite for a session at layer 5 to layer 1:


First a tunnel is created. Then one or more sessions are created. Tunnel is between LAC - LNS, session is end user specific.

The simplified version of the question is:

Cisco states: "Numbers in the table are based on one session per L2TP tunnel" and the number can be e.g. 1200.

Can I have 1 L2TP tunnel with 1200 sessions?



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