04-09-2007 12:59 PM - edited 03-03-2019 04:28 PM
Is the idea behind bridging across WAN links to allow a remote site to be on the same layer 2 link and subnet as the Main site?
For example in a DR scenario, you could configure the DR site to be on the same subnet as the Main site as far as the remote branches are concerned?
04-09-2007 01:27 PM
What is DR?
yes, with bridging everything will be in the same L3 subnet. That is usually a bad idea especially for WAN links because:
- wasted bandwidth due to broadcast/multicast flooding
- overhead due to L2 addresses in WAN packets
- cannot to compress traffic
- cannot crypt traffic
- poor control of traffic flow due to inability of L3 separation
- harder to diagnose and troubleshoot.
- much harder to design for a backup.
- no performance advantage over routing, actually the opposite.
If you are new to networking, don't think that bridging is a shortcut to success, it is not.
04-09-2007 03:17 PM
Thanks for the reply,
DR is the Disaster Recovery site.
This was set up by someone else, they have a bridge connection from the Main Site to the Disaster Recovery site.
All the Server subnets are in the same VLAN(I think why they did it this way).
04-10-2007 12:51 AM
There is no reason for a disaster recovery site to use bridging instead of routing. The real problem is: "If I bring down the main site, how and by which addresses the branch sites and other offices will connect ?".
Bridging in itself does't offer a solution to this problem.
Unfortunately, there is no easy answer. each application, vendor, integrator can propose a different solution and I have yet to see one that is totally satisfying. Then it depends by the customer. Some are happy just having an almost ready copy of all-data, other pretend small switching times.
Designing something that works for real (not on paper only) can be difficult, expensive and time-consuming.
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