We will shortly be upgrading the remaining Forum core network switch. With this one there will be some (expected) visible effects, as follows:
- This switch is normally the “root bridge” for the entire Informatics network. While we do have extensive redundant connectivity, the active paths are usually based around this switch being at the centre. To minimise the effect of removing this switch from the network we will deprioritise it in advance, at an off-peak time, which will have the effect of rebalancing the spanning-tree to use a different root. After the replacement switch is installed and configured, and we are happy with the way it is running, we will again rebalance the spanning-tree back to using this switch as its root. On each of these occasions we anticipate there may be a few seconds of network disruption while the spanning-tree is recalculated.
- Being at the centre of the Forum network, we normally use this switch as the primary router for most of our subnets. To allow time for DHCP-configured hosts to pick up the change we will move this function to a different core switch a couple of days ahead of the upgrade. Other than a visible change in path and a little extra load on our intra-core links there should be no effect from this change.
- While the upgrade is being carried out the link to the Forum’s external router will fall back from 10Gbps to 1Gbps. There is a chance that external connectivity will appear slower while the upgrade is taking place as a result of congestion on this slower link. We will try to minimise this by making this router’s link one of the last to be removed from the old switch and one of the first to be made to the replacement.
Apologies in advance for any disruption this work causes. This is the last of the old Forum core switches to be replaced. They were bought new over ten years ago when we moved into the Forum, firmware is no longer being released for them, and the replacements are considerably more powerful and so better able to handle the additional load from Bayes as well as the faster Forum edge connectivity.
Technical network documentation is here.