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MTU help needed

guys i have read some where that we shd config MTU size 1460for L2TP its recommended now iwe have a router on which L2TPv3 is config ......kindly see below

pseudowire-class XXXX

encapsulation l2tpv3

protocol l2tpv3 l2-dyn

ip local interface Loopback0

ip pmtu

now what is pmtu config under....scondly we want to change the mTU size to 1460 where i have to do it i have to do it on loopback0 or Xconnect interface....i cant get my head around it....plz help me an dexplain do i have to change this pmtu as well

Hall of Fame Super Silver

Re: MTU help needed

Hello Khan,

refer to the MTU handling section in L2TPv3 config guide

ip pmtu enables ip mtu path discovery so you may be fine already with this configuration.

Hope to help


New Member

Re: MTU help needed

Hi Giuseppe

Thankyou very much for your help as its always very help....Now i have a quick question we have a site which has 2800 series router and that site is connecting over a WAN to data centre making a L2Tp tunnel....there is a server stack at the data centre and when from client site pc we do extended ping there is a 3 to 2 % packet after digging info we couldnt find anything wrong in the we have decided that to put sniffer wireshark at on server and on same time on client pc (client ssh the servers ) to see what actually is happening the problem is that client is using putty and the connection get drop frequently some time after 4 min some time after 10 its not too i have never used wireshark can you give some good tips what to config in wireshark and how to do we filter SSh traffic i want to see the specifi conection.....any help from your side would be a gr8 one as its always help me....thanks and waiting for your response (plz tell me the steps to do in wireshark and any other help)

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