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.
At the above time today, we will be replacing 1 line card in each of the above cores with a newer revision to facilitate an update on LNS01 & LNS02.
Any traffic on these cards will be re-routed to there backup counterpart . No outage is expected however a drop in call traffic may be observed.This devices should be considered at risk until complete.
UPDATE01 – 09:55
Work has been undertaken to re-route traffic on CORE02. As expected we have seen a small drop in call traffic. We apologize for any inconvenience caused. Traffic will need to be re-routed, however will be done at a time when call levels are lower.
UPDATE01 – 11:30
Work has been completed on both cores and any primary services reconnected.
We have been advised of planned network maintenance by one of our primary transit providers (Adapt) This work is due to retirement of access41.lon2 and the need to move the network equipment into new core cabinet within Goswell Road.
We have been advised works will start at 20:00 and continue on until 04:00 on the 16th. We take multiple feeds from adapt for transit and have been advised of service disruption while these are physically relocated to the new device of up to 20 minutes. Although we take multiple redundant feeds, we have been advised of disruption due to network re-convergence on there side.
Our network is comprised of multiple redundant routes to different carriers. Should we loose our Adapt link for any reason then traffic will automatically re-route with minimal disruption.
This work wont affect phone services as these route in to our network via interdependent private interconnects unless you connect in to our network via a 3rd party connection. If this is the case you may need to restart your handsets after the maintenance works has been completed.
UPDATE01 – 16/10/2015
This work completed without issue from our supplier. Our network reacted as expected and re-routed traffic where required.