[HECnet] Multiple Area routers on one area?

[Paul_Koning at Dell.com]

That's fine, and feasible, and in fact highly recommended if you want to build a robust network.

The one thing to keep in mind is that you need to make sure the area is not partitioned.   In other words, if you build for fault tolerance, first concentrate on protecting the area from partitioning.   Having done that, build redundancy into the level 2 network.

If you have two L2 routers out of the area, and that area is partitioned, traffic inbound will land on whichever area router is on the shortest path from the source.   Area routing (L2 routing) is not aware of the details of what's inside areas; it only pays attention to the area part of the address.   So there's a 50/50 chance that the router where the packet arrives into the destination area is the one that can't reach the destination.

BTW, this is a direct analogy with the IP requirement that you have to protect against partitioned subnets, and for the same reason.

I'm not sure from your description, but if what you're trying to do is to have two clumps of nodes that both call themselves area 6, but they aren't connected by L1 routers, the answer is that doesn't work anymore than two clumps of IP hosts that aren't connected but still claim to be in the same subnet will work.   Don't do that.

	paul

On Jul 23, 2012, at 7:33 PM, Mark Benson wrote:

Is it feasible/advisable/possible to have 2 Area Routers on a DECnet Phase IV network?

The only reason I ask is that I'd like my emulated cluster system to be able to run Area 6 independently as all the nodes are area 6 nodes and it'd be neat to have area 6 working at places events like DEC Legacy.

Would it cause issues on HECNet having 2 Area 6 routers in different places also? I'm guessing not as they are still on the same DECnet network, same as if they are in the same room on the same LAN, but what do I know ;)

-- 

Mark Benson

http://DECtec.info
Twitter: @DECtecInfo
HECnet: STAR69::MARK

Online Resource & Mailing List for DEC Enthusiasts.