[RndTbl] Multihoming

Bill Reid billreid at shaw.ca
Wed Jun 6 18:48:04 CDT 2007

Trevor Cordes wrote:
> On  5 Jun, John Lange wrote:
>> I'm in a nit-picky mood so I'll just point out that plugging 2
>> connections into a firewall that supports dual wan is not multi-homing.
> http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212611,00.html


Trevor is sort of correct. The wikipedia entry is pretty good.

I agree with John that the original meaning of multihomed means more than one 
way to get to a host. The optimal method is to have multiple interfaces to the 
same IP address. Each interface is connected to a different ISP. So an IP 
address has multiple routes to it. This provides redundancy for people trying to 
connect to your servers. Of course to do this you need an AS number and be 
running BGP in your router. For example a TCP session could continue even if the 
interface that it is currently on goes down.

Trevor is really talking about providing redundant access to the Internet. It is 
not really true multihomed since a TCP session will break if the current 
interface goes down. It is not as helpful for people trying to access your server.

-- Bill

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