Re: Multiple upstreams

Rudy Komsic ( (no email) )
Mon, 10 Aug 1998 15:22:04 -0400

>>-----Original Message-----
>>From: Stuart Stevenson <>
>>To: <>
>>Date: Sunday, August 09, 1998 11:20 PM
>>Subject: Multiple upstreams
>>We're currently doing a little web hosting via a 128k ISDN and an Ascend
>>Pipe 50. We have a class C from PSI and have been humming along just fine.
>>Now we're starting to feel the pressure to add bandwidth and have struck a
>>deal with a neighbor to pull in a 10-Base-T cable from his 2 T1s.
>>The plan is to use a Cisco router between our suite and theirs. We can get
>>another Class C from these guys, but we would also like to keep the PSI
>>connection as a backup.
>>We've got a few questions on how to do all this:
>>1) Is it possible (and reasonable) to have both connections active at the
>>same time?

If your talking about Load Balancing, yes it is possible but you got to make
sure you have the same "PIPES" in both connections.

>>2) If so, can we do it and keep the PSI address block with routing via the
>>new upstream (which is connected to Verio) or get PSI route to our Verio

Using BGP4 would be the safest way to go to configure this but DO NOT
CONFIGURE this yourself. If it is your first time doing BGP, contact both
providers to SHOW you how BGP Works and is implemented. If you screw up, you
can take out 25-75% of the North American Internet and Lots of Backbone
providers will be angry.

>>3) If not, is it reasonable to setup two subnets (1 PSI block and 1 Verio
>>block) with each virtual server assigned an address in each subnet? I am
>>thinking if we do it this way, I could have our primary DNS on the Verio
>>subnet, pointing to Verio addresses, with our "secondary" setup as a
>>on the PSI subnet, with all it's A records pointing to the PSI block. I
>>know it's twice the work, but (to me anyway) it makes sense and would
>>provide complete connection redundancy.

For reduncancy purposes, you can do the following,

each machine will have 2 IPs and 2 Default gateways. One each from Verio
(Primary address) and other from PSI. In your DNS PTR records, make sure you
define both IP addresses the same name. For the A Records, Make the Primary
address first and the secondary address second. Know if your Verio link goes
down, the client from the Internet would first try the verio link, it sees it
is down so therefore then tries the second connection. Theoretically
speaking, the link should revert via PSI and if the first default route is
down or not reachable, it should try the second route.

Then again, it all depends on the Server software you use to see if it
supports multi routing.