[cisco-bba] LAC/LNS --> L2TP MTU issues

[Tihomir Dragas]

> 
> Hi Christian,
> 
> I have working 7206VXR LNS, with following config:
> 
> !
> interface Virtual-Template1
> mtu 1492
> ip tcp adjust-mss 1420
> ppp mtu adaptive
> !
> 
> You could try this config also, I think it will work.
> 
> Regards,
> 
> Tiho D.
> 
> 
>> 
>> ----- Original Message ----- 
>> From: "Christian Schmit" <cschmit at vo.lu>
>> To: <cisco-bba at puck.nether.net>
>> Sent: Monday, May 15, 2006 10:57 PM
>> Subject: [cisco-bba] LAC/LNS --> L2TP MTU issues
>> 
>> 
>>> Recently we encountered MTU issues on our
>>> DSL connections. We run a typical LAC-LNS 
>>> setup with the telco. LAC on the telcos 
>>> side are ERX boxes while the LNS used are
>>> Cisco7200 with G1.
>>> 
>>> Affected by the MTU problems were some IPSEC VPNs
>>> and radius connections.
>>> 
>>> While browsing through different sample configs
>>> on the Internet I found the following commands
>>> to be useful to address the mtu problem.
>>> 
>>> 
>>> virtual template commands:
>>> -------------------------- 
>>> 
>>> - ip tcp adjust-mss xxxx
>>> - ppp mtu adaptive
>>> - ip mtu xxxx
>>> - mtu xxxx
>>> - clearing the DF bit using a route-map
>>> 
>>> vpdn-group commands:
>>> --------------------
>>> 
>>> - ip mtu adjust
>>> - ip pmtu
>>> 
>>> 
>>> 
>>> My current LNS config regarding MTU is:
>>> ---------------------------------------
>>> 
>>> vpdn-group 1
>>> accept-dialin
>>>  protocol l2tp
>>>  virtual-template 1
>>> terminate-from hostname LAC
>>> lcp renegotiation always
>>> l2tp tunnel password 7 xxxxxxxxxxxxxxxxxxxxxxxx
>>> ip mtu adjust
>>> .
>>> .
>>> .
>>> interface Virtual-Template1
>>> ip unnumbered Loopback1
>>> ip tcp adjust-mss 1420
>>> ip mroute-cache
>>> peer default ip address pool DSL_POOL1
>>> ppp authentication pap chap
>>> !
>>> 
>>> 
>>> If anybody could comment on what combination of
>>> commands is best to be used to solve the mtu 
>>> problem would be great.
>>> 
>>> Christian
>>> 
>>> 
>>> 
>>> _______________________________________________
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>>> cisco-bba at puck.nether.net
>>> https://puck.nether.net/mailman/listinfo/cisco-bba
>>>