is it possible to limit the number of hops in a hub route?
Article ID: 378684
Updated On:
Products
Issue/Introduction
I have several DX UIM Hubs connected via layers of tunnels in a "chain" fashion. Is there a way to ensure that traffic in such an environment always takes the shortest route? Can the number of hops be limited?
Environment
DX UIM Hub - any version
Tunnels - multiple tiers of hubs
Resolution
The DX UIM hub algorithm will automatically try to find the shortest route, as follows:
- each hub shares the list of hubs it knows about with every other hub, along with a value showing the "proximity" or number of hops to those hubs
- if an update comes from a hub that has a lower proximity value than the current route, it will be updated
- if an update comes from a higher or same proximity hub, it will be ignored
Over time, this results in the shortest routes automatically being calculated as each hub will seek out the lowest proximity route to each other hub.
Additional Information
In an environment with a mixture of static hubs and tunnel routes, this process may not always result in the shortest route being taken, because a static hub with a tunnel connection will be seen as "proximity 0", and a local/direct tunnel connection will also be seen as "proximity 0", so sometimes the static hub route will get into the system first, and the direct tunnel route will be seen as "same proximity" and be ignored even though it is one hop closer.
In most environments this will not cause any issue, as the route will still be valid either way, but in a larger environment it may cause issues with hub accessibility in Infrastructure Manager/Admin Console, where a number of hubs may be unexpectedly showing as red/inaccessible at various times.
If this behavior is observed, it is advised to replace all the static hub connections with tunnel connections, and set "broadcast_on = no" on every hub. This will limit the cross-pollination of routes and allow the shortest routes to be calculated appropriately.
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