We are aware of a MTU issue on our DSL network affecting lns01.dsl.structuredcommunications.co.uk. This is preventing JUMBO FRAMES from getting to this device and forcing DSL circuits that terminate on our network to obtain a lower MTU (1460-1462) Where end users CPEs and networks are not configured to handle fragmentation correctly this will manifest itself as access problems to various websites.
We are currently working to resolve the problem.
We apologise for any inconvenience this may cause.
UPDATE 01 – 13:56We have isolated the problem to a interconnecting VLAN between LNS01 & CORE02. The VLAN will need to be reconfigured, however this will drop all active DSL sessions that terminate on that device. We are looking at other work around at this time.
UPDATE 02 – 14:20 We have reconfigured the VLAN and interface which has resolved the issue with JUMBO frames and our carriers. Existing L2TP tunnels to our carriers LACs are still negotiated at a lower MTU. Any existing sessions and new session that join that tunnel will still have a lower than normal MTU.
UPDATE 03 – 16:00 Tunnels have been reset and sessions restored. MTUs are now being seen at 1500 again for ADSL.