FWeston
asked on
What do I need to run BGP?
I work for a small business that currently has a Cisco 2801 router and 3 Mbps to the Internet via bonded T1s. All of our IP addresses are assigned from our ISP. We're looking at upgrading to a 15 Mbps fiber connection with another ISP, and would like to know if we could achieve connection redundancy by keeping our current Internet service as well.
Basically, we'd like to use the 15 Mbps service as the primary connection and have the ability to have all of our inbound/outbound traffic switch over to the 3 Mbps service we currently have if the 15 Mbps line goes down.
I understand that I will need to obtain an AS number from ARIN, but was unclear how the IP assignments work. Do I need to have a direct assignment from ARIN, or can I continue using addresses from my ISP? I only have a block of 64 addresses with about half in use, so it would appear that I do not qualify for a direct allocation since ARIN's minimum is a /22.
I have pasted the output from show version below. I need to know if my current router would work for what I would like to do.
Basically, we'd like to use the 15 Mbps service as the primary connection and have the ability to have all of our inbound/outbound traffic switch over to the 3 Mbps service we currently have if the 15 Mbps line goes down.
I understand that I will need to obtain an AS number from ARIN, but was unclear how the IP assignments work. Do I need to have a direct assignment from ARIN, or can I continue using addresses from my ISP? I only have a block of 64 addresses with about half in use, so it would appear that I do not qualify for a direct allocation since ARIN's minimum is a /22.
I have pasted the output from show version below. I need to know if my current router would work for what I would like to do.
Cisco IOS Software, 2801 Software (C2801-ADVIPSERVICESK9-M), Version 12.3(8)T6, RELEASE SOFTWARE (fc2)
ROM: System Bootstrap, Version 12.3(8r)T8, RELEASE SOFTWARE (fc1)
System image file is "flash:c2801-advipservicesk9-mz.123-8.T6.bin"
cisco 2801 (revision 4.1) with 236544K/25600K bytes of memory.
2 FastEthernet interfaces
2 Serial interfaces
1 Virtual Private Network (VPN) Module
1 DSP, 8 Voice resources
WIC T1-DSU
DRAM configuration is 64 bits wide with parity disabled.
191K bytes of NVRAM.
62592K bytes of ATA CompactFlash (Read/Write)
Don Johnston
Actually, you don't need to run BGP to achieve your goals. Depending on your internal topology, you can use either an interior routing protocol (RIP, EIGRP, OSPF) or HSRP.
ASKER
Sorry, I don't think that's correct (although correct me if I'm wrong). We run web and mail servers at our office. If one of the connections goes down, I want those servers to still be available to the Internet using the same IP addresses. In other words, I want to publish www.mycompany.com in DNS to one of my IP addresses. I want that IP to be reachable when connection A fails or connection B fails. As I understand it, the routing protocols you named would only work for outbound requests (from me to the Internet), my primary concern is the other way around.
Thanks
Thanks
Hi .. you would first need to work with the new ISP to see if they would even accept routes to a subnet range that they do not own. Iam not sure many ISPs allow this.
Each of your ISP's would create a static route for your network. They would advertise this route with BGP to their neighbors. If the link fails, they would stop advertising it.
Now if you want to control how traffic enters your network, then yes, you would need to use BGP.
But for basic routing, you don't.
Now if you want to control how traffic enters your network, then yes, you would need to use BGP.
But for basic routing, you don't.
ASKER
Well, yes...ideally I'd want all traffic to enter the network over the fastest available link. I'm okay with the slower link doing nothing most of the time.
You can still do it without BGP. Just have the provider on the slower link advertise a higher metric.
ASKER
When that link goes down, what is the delay for the upstream provider to stop advertising the route?
Well, the provider will advertise their path to your network is down as soon as the link failure is detected. Then it's up to all the other routers to converge.
If you run BGP or just let your provider advertise your network, there's really no difference in convergence time.
But ultimately, you'll need to discuss with your providers how you're going to do this. Some providers don't want to run BGP with their customers others do.
If you run BGP or just let your provider advertise your network, there's really no difference in convergence time.
But ultimately, you'll need to discuss with your providers how you're going to do this. Some providers don't want to run BGP with their customers others do.
ASKER
Our new ISP suggested that we look into running BGP, which is why I'm asking the question. Assuming that we do choose to run BGP, I guess the main questions I have are 1) will we need a new router, and 2) will we need to obtain an IP block from ARIN?
>1) will we need a new router
No, the 2800 can run BGP. You don't need to receive the full BGP table so your memory is fine too.
>2) will we need to obtain an IP block from ARIN?
That's one way. You could also get a block from one ISP. But you'd need to make sure your other ISP will allow you to connect to their network with that block.
No, the 2800 can run BGP. You don't need to receive the full BGP table so your memory is fine too.
>2) will we need to obtain an IP block from ARIN?
That's one way. You could also get a block from one ISP. But you'd need to make sure your other ISP will allow you to connect to their network with that block.
ASKER
Ok, I think the next answer will wrap this up....am I even eligible to receive a block from ARIN since their minimum multihomed allocation is a /22 and I don't have anywhere near that many addresses currently? If the answer is no, then it would seem I am only capable of running BGP if one ISP allocates a block to me and the other is willing to connect me to their network using that block as you've said in the previous post. Is that correct?
ASKER CERTIFIED SOLUTION
membership
Create a free account to see this answer
Signing up is free and takes 30 seconds. No credit card required.
ASKER
Excellent. Points awarded, thank you.