04-19-2012 12:48 PM - edited 03-04-2019 04:05 PM
We have established l2tpv3 implementation with IPSec VPN between 2 routers which is connected 100 Mbps metroethernet. In this scenario we are using layer 2 traffic over layer 3.
Everything is running perfect except MTU size problems. While we were send icmp messages upto 1472 bytes in local network, we can send maximum 1426 bytes icmp packets through l2tpv3 connection. Some applications get network error messages. I have also removed dfbit set line and ip pmtu line from the configs but nothing changed.
Any help to solve this issue will be highly appreciated.
Thanks
Ferruh
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04-24-2012 03:14 AM
Hi Ferruh,
am not too sure what seems to be a problem here, both L2TPv3 and IPSec(depending on mode) add up their own headers, which decrease maximum payload size that can be send out.
HTC
04-24-2012 11:11 AM
As I read more documents, it seems that i will need an iOS upgrade. I have done the settings on old demo routers from Cisco. Now our new 3945s arrived and I will make the same config on them. I hope it will work this time.
Thank you very much for your help. After the test I will write the result.
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