BGP multihome with two isp's

Answered Question
Sep 30th, 2009

Hi all,


I have two ISP's for internet access and I want to set up bgp multihome for redundancy and be able to advertise a block of /24 public ip addresses through both ISP's.

Questions:

1. Do you think two 1811 routers with 256MB would be enough to do the job?

2. Can I avoid recieving the full routing table from both ISP's and still have redundancy?

3. Any configuration examples for my scenario would be greatly appreciate it.


Thank you very much for your help....


Cheers!

Correct Answer by csco11142276 about 7 years 4 months ago

1). Do you think two 1811 routers with 256MB would be enough to do the job?


Depends upon your internet links BW, generally if it's 10Mbps or less 1841 will do the job.


2). Can I avoid recieving the full routing table from both ISP's and still have redundancy?


It is unlikely that you'll recieve full internet routing table, Your ISP would simply announce default route ( pointing to their internet gateway) in the BGP or another routing protocol table used between your internet router and their gateway or uplink device could be PE (depends how they are providing internet connectivity).


3. Any configuration examples for my scenario would be greatly appreciate it.


Try this http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml


Rate if this helps





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Edison Ortiz Wed, 09/30/2009 - 05:33

1. Do you think two 1811 routers with 256MB would be enough to do the job?


Large, medium or small site?


1811s are targeted for small sites with very little bandwidth demands. I'm assuming your ISP handoff is copper as the 1811 does not support any serial connection. You will find the 1811 maxing out at around 35Mbps


http://www.cisco.com/web/partners/downloads/765/tools/quickreference/routerperformance.pdf


2. Can I avoid recieving the full routing table from both ISP's and still have redundancy?


To have redundancy, you need routes to compare. With a 1811, your only option is taking the default from the ISP. I don't think the 1811 will be able to take partial routes.


3. Any configuration examples for my scenario would be greatly appreciate it.


I'm afraid you need a more powerful router for this type of task.


__


Edison.



xcz504d1114 Wed, 09/30/2009 - 06:13

1. Do you think two 1811 routers with 256MB would be enough to do the job?


Other posters have answered this well.


2. Can I avoid recieving the full routing table from both ISP's and still have redundancy?


Yes, but I would not do the filtering yourself, you can request from your ISP to only send you the default route. If you filter it yourself you still recieve the updates, and if soft configuration is configured, you will still store the entire internet routing table in memory, it just wont be inserted into the BGP routing table.


3. Any configuration examples for my scenario would be greatly appreciate it.


As someone already mentioned, that is a long conversation with a lot of "if's" and "and's".


HTH,

Craig

Correct Answer
csco11142276 Wed, 09/30/2009 - 11:39

1). Do you think two 1811 routers with 256MB would be enough to do the job?


Depends upon your internet links BW, generally if it's 10Mbps or less 1841 will do the job.


2). Can I avoid recieving the full routing table from both ISP's and still have redundancy?


It is unlikely that you'll recieve full internet routing table, Your ISP would simply announce default route ( pointing to their internet gateway) in the BGP or another routing protocol table used between your internet router and their gateway or uplink device could be PE (depends how they are providing internet connectivity).


3. Any configuration examples for my scenario would be greatly appreciate it.


Try this http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml


Rate if this helps





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