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Hi, my company is looking at beefing up our internet connection (currently a
point to point T1 to an ISP) - replacing the ISDN backup with a T1 line to a
second ISP. We would like to run BGP to make the redundancy work best. The
new ISP requires that both internet subnets be at least /24 subnets, giving
us a total of 508 public addresses (254 from each ISP). We currently have a
/28 subnet (14 addresses). It's true that we could probably use more
addresses since we are running out so I'm not complaining about getting a
ton more addresses- Just wondering if this is a normal requirement, needing
two full Class C subnets.

Richard Field

In article <ct3dc.94362$K91.213825@attbi_s02>,
"Richard R. Field" <> wrote:

> Hi, my company is looking at beefing up our internet connection (currently a
> point to point T1 to an ISP) - replacing the ISDN backup with a T1 line to a
> second ISP. We would like to run BGP to make the redundancy work best. The
> new ISP requires that both internet subnets be at least /24 subnets, giving
> us a total of 508 public addresses (254 from each ISP). We currently have a
> /28 subnet (14 addresses). It's true that we could probably use more
> addresses since we are running out so I'm not complaining about getting a
> ton more addresses- Just wondering if this is a normal requirement, needing
> two full Class C subnets.

You should only need *one* /24 network, not two. You don't need a block
from each ISP, just from one of them. You'll then advertise that one
network through both ISPs to get failover.

The reason you need a full /24 is because many ISPs will filter out BGP
advertisements smaller than this. Any ISP that doesn't see the
advertisement will not get the full benefit of the failover.

--
Barry Margolin,
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

[theapplebee]

As customer perspective, the IP from ISP would be non-portable IP address which means when you break contract with the ISP, you MUST return the IP.
So, you better to have /24 from both ISP in case anything happens with the ISP

please read below article before setting up BGP

http://showipbgp.com/bgp-knowledge-b...-need-bgp.html