Friday, July 01, 2011

A switch port too far

As part of the ongoing upgrades surrounding the recent issues that the CEs have had when communicating with svr016, we decided to upgrade the core backbone link to 20 Gigabits. Presently, we have one 10 Gigabit trunk link between 141 and 243d, which is occasionally saturating with traffic.

As previously posted, we disabled the 10 gigabit link into Stack01 and used the XFP GBIC recovered from it to facilitate this new link. Sam and I laid new fiber optic patch leads in both rooms to the patch panels and connected these to spare ports on the Core Dell 8024F and Stack02's 5530.

However, the link refused to come up. After several hours investigation we acquired a fiber optic line tester which proved that light was coming through the new link. We then tested the ports on both switches with a fiber optic loop.

While the port and GBIC in the 8024F looped correctly, you get a rather re-assuring green link light on the transmit and receive port, it failed on the port in Stack02. We retested the XFP in its old unit, stack01 and it came up correctly using the loop.

While we are using 62.5 um patch leads which, under the standards can't be driven as far as 50 um,  we thought this may have been the issue, we confirmed that this wasn't the case through the re-testing of all the components end to end with the fiber optic meter.

We cleaned out the interface slot on the Stack02 5530 with compressed air and isopropyl alcohol,  the port, while recognising the gbic correctly, did not bring up the link.  We fear that the on board optical interface is damaged, however we would need to put the site into downtime to confirm this, so we have come up with a Plan B.

As we have successfully built a LAG between 141 and 243d which is in place and did not impact service at all during its commissioning, and have laid in the fiber interconnect,  we have decided to investigate moving our second 5530 into Stack02 from Stack01 to give us the 20 Gigabit uplink that we require within the core of the network.

More on this after the move. 

As an aside, you never know how windy cold aisles are, until you lift a floor tile. Sam is on the floor in this image and not glued to the ceiling as his hair direction may imply.

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