04-22-2009 02:41 AM - edited 03-04-2019 04:28 AM
Hi
I have internet connectivity with 2 Internet service providers and i am doing BGP with them.I am using Cisco 3845 router for my internet connectivity so in BGP i just want to accept default route from the service provider and not the complete routing table.
i want to block the complete routing table from both the service providers.how i should proceed.Any sample config to block the same.
04-22-2009 03:18 AM
Besides filtering out received BGP routes to only accept a default, you might also discuss with your ISPs not sending the complete BGP route table and only sending the default.
04-22-2009 03:23 AM
Hi
I want to ensure the same from my end so wants the configuration details..
even if we confirm with isp about default route,some misconfiguration at there end at any point of time can make the 3845 router down.
please suggest the necessary configuration
04-22-2009 03:33 AM
Assuming the default-route provided by provider is 0.0.0.0 then on your router(s)
access-list 1 permit 0.0.0.0
access-list 1 deny any
router bgp
neighbor
Jon
04-22-2009 03:39 AM
Didn't mean to infer you shouldn't filter out BGP routes, just made suggestion in case you hadn't considered it. What I had in mind was, why burn bandwidth passing the Internet BGP table if you don't want it.
If you're that concerned about ISP misconfigurations, and you never intend to use anything but the defualt, why BGP peer at all? Sure BGP can indicate a "dynamic" default, but if you don't trust your ISPs, you might want to use your own "dynamic" default.
As to suggesting a necessary configuration for your original question, don't believe it should be difficult, but I don't know it off the top-of-my-head. I'm sure another poster will provide it. (Again, just wanted to insure you've been considering other aspects.)
[edit]
PS:
Ah, Jon provided the configure while I was typing the above.
04-22-2009 06:59 AM
Hi
The reason to use BGP peer is i have 2 diffrent isp's to whom i am announcing my own ip address pool.
The reason to get default route is the capacity of my 38xx router which i feel wont be able to take complete routing table.
04-22-2009 09:14 AM
The following prefix list will only allow a default route only.
ip prefix-list test seq 5 permit 0.0.0.0/0
Check the following:
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a008009456d.shtml
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