BGP using a cable modem patched to an Ethernet port on a router

rstevek · ‎01-07-2008

Hi,

I have to configure a redundant Internet access solution for a company that has a 2801 router, a T-1 from one service provider, and a cable modem from Time Warner. I had planned to install a HWIC-CABLE-D-2 into the 2801, but Time Warner flatly refuses to support this configuration.

The second Ethernet on the 2801 is currently unused, and we have five static, public IP addresses from Time Warner. So I can go from an Ethernet port on Time Warner's equipment to an Ethernet port on the router. Can BGP be configured this way?

Thanks,

- Steve

Collin Clark · ‎01-07-2008

No. In BGP you are advertising your public address space. You need to purchase an Autonomous System Number and usually the IP address space as well. What are your requirements (outbound failover, inbound and outbound failover, etc) and we'll see if we can help.

HTH and please rate.

rstevek · ‎01-07-2008

Hi,

Thanks for the help! The company was using BGP at one point, when they had two T1s from AT&T, before moving to the new ISP. So they presumably own an AS number, although I might have trouble finding out what it is.

At any rate, the requirements are outbound failover, and serving up some Web apps.

Thanks,

- Steve

Collin Clark · ‎01-07-2008

Is it safe to say they want to continue to use BGP? BGP will allow for inbound failovers.

rstevek · ‎01-07-2008

I don't think they care so much about the specific protocol used. The main app they are serving was moved to as hosting facility; the lines at the office (which is what I'm working on) are mainly used for outbound. They will; however, be used for some "peripheral" inbound apps in the future.

Thanks,

- Steve

Collin Clark · ‎01-07-2008

OK. Here's my 0.02, put ALL the hosted apps at the hosted facility. It will save $ and headaches. Only BGP can work around ISP failures. If you plan on hosting apps and not using BGP, you will run into problems, delays when/if there is an outage. We can load balance outbound no problem. Do we need to talk about BGP some more or just the outbound stuff?

rstevek · ‎01-07-2008

Hi,

I would love it if they would keep all of their hosted apps in the datacenter, but that's a long and complex story. At any rate, the things that they would be serving from their office in the future will not be critical. It seems like BGP is out.

I'm thinking that I can patch the cable router to the third Ethernet port on their ASA, instead of to the router. They will still have two outbound paths, that way, and they can just serve the app over one of the two inbound paths.

Collin Clark · ‎01-07-2008

That sounds good!

rstevek · ‎01-07-2008

Thanks for all the advice!

chschroe · ‎01-07-2008

Where would you be talking this BGP to, is the question.

Doing outbound failover that way is pretty easy. You just monitor one interface with EOT, and if it goes down you switch everyone over to the other. You'd need to have nat configured on both, of course.

The inbound apps you can't really provide that failover for. You won't be able to route traffic from one set of IP space to the other without some sort of external influence like a global site selector or similar.

NS

rstevek · ‎01-08-2008

Hi,

I've decided that I can't use BGP. The Time Warner router doesn't support it, for starters.

At any rate, they don't want failover for inbound apps. The actually want to use two distinct paths with two different addresses for the same server. The idea is to have patches delivered over both paths, with the client application deciding which path has lower bandwidth usage. That's why I'm going to have both routers patched to the ASA.

Thanks,

- Steve