On Wed, Jun 19, 2013 at 8:57 PM, David Woodhouse <dwmw2 at infradead.org> wrote: > The MTU is per-link. The Ethernet link between your internal clients and > the router, over your wireless or wired network, *is* 1500. It's not > giving you incorrect information. > > The MTU on the link between the router and the ISP is (presumably) 1492. > At a slight tangent, and apologies if I'm "teaching granny to suck eggs". When I moved from a PPPoA to PPPoE connection I had a lot of "fun" with AnyConnect (on Windows). Until I got a router that supported RFC4638, I had some success with setting the MTU on the NIC of the computer running AnyConnect the AnyConnect client to 1492 and setting a MTU of 1398 in the appropriate group policy on the ASA. group-policy <policyname> attributes webvpn anyconnect mtu 1398 The default MTU is 1406, so I reduced by 8 to cover the PPPoE overhead "MTU?Adjusts the MTU size for SSL connections. Enter a value in bytes, from 256 to 1410 bytes. By default, the MTU size is adjusted automatically based on the MTU of the interface that the connection uses, minus the IP/UDP/DTLS overhead." Granted I managed the ASA and knew that I didn't have anything that had an MTU as low as you appear to have in the path.... Cheers Arne
