ipsec tunnels & packet length issues

Lars Eggert larse at ISI.EDU
Wed Oct 29 13:03:53 PST 2003


Eric Masson wrote:
> 
> If i reduce  lan interface mtu on "Host" to approximately 1450, the
> tunnel works fine, so it seems that "Tunnel Endpoint" can't process
> correctly packets with a size of 1500 bytes.
> 
> If more information regarding this issue is needed, just ask.
> Is this a known issue ?
> Except playing with mtu, is there a fix ?

See the section on PMTU discovery in draft-touch-ipsec-vpn-06. If the 
requirements of your setup allow is, IPIP gif tunnels together with 
IPsec transport mode (as described in the ID) can address this issue.

Lars
-- 
Lars Eggert <larse at isi.edu>           USC Information Sciences Institute
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