10-26-2009 11:51 AM - edited 03-04-2019 06:30 AM
Trying to figure out how to handle routing internet traffic through branch office that has their own ISP however corporate office has default route set.
Current Setup
==================
ISP <--- SITE A (Corporate Office) ---[MLPPP Link]--- SITE B (Branch Office) ---> ISP
A has a default route 0.0.0.0/0
B has A's default route through EIGRP
==================
How can I have B route internet bound traffic through B's ISP and not through A's ISP?
Looking for any options. I would however like to have a failover back to A if B's ISP is down, or vise-versa.
A and B both have Cisco 3825's.
Solved! Go to Solution.
10-26-2009 12:25 PM
At site B add a static route with ISP (B)
ip route 0.0.0.0 0.0.0.0
If the ISP access link is down, it will use the EIGRP route through site A.
10-26-2009 12:44 PM
You can use distribute-lists within EIGRP to filter which routes, either outgoing or incoming on an interface, are allowed -
https://www.cisco.com/en/US/docs/ios/12_1/iproute/command/reference/1rdeigrp.html#wp1024147
Jon
10-26-2009 12:25 PM
At site B add a static route with ISP (B)
ip route 0.0.0.0 0.0.0.0
If the ISP access link is down, it will use the EIGRP route through site A.
10-26-2009 12:28 PM
Thanks, I just found this out through here -> http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094195.shtml
I can manipulate through distance values.
10-26-2009 12:26 PM
Ryan
Simplest solution would be to have a default route in site B also pointing to the ISP in site B.
Use an offset list and increase the metric of the default route from site A so that the default route in site B is preferred. If the default-route from Site B is lost then the one pointing to site A will be used. So you would apply the offset-list to the LAN facing interface on Site B WAN router that connects Site B to Site A -
Jon
10-26-2009 12:26 PM
Ryan
Some things about how to implement this would depend on details of your environment which we do do know. But in general you should be able to have siteB send its traffic to the Internet through its own Internet provider by configuring a local static default route. The local static default route would be preferred to the learned EIGRP default route. And if the local route is withdrawn from the routing table because the siteB provider is down, then the learned EIGRP default route would be used, which provides the fail over that you want.
HTH
Rick
10-26-2009 12:33 PM
Rick
Agreed but that is assuming that Site B only has one router. Appreciate as you say we don't know the full topology but if Site B has more than one router and runs EIGRP internally then a local static default route would not work by itself.
Hence the reason i suggested an offset list. However if there is only one router in Site B then a local static route is the way to go.
Jon
10-26-2009 12:37 PM
There is only one router there.
My next question would be what if there was a second branch office with and ISP. These static routes would be getting distributed via EIGRP so is there a way to not distribute a static route through EIGRP, as an exclusion perhaps?
With the specification of 'no redistribute static' in EIGRP this should work at the branch office router without distributing that route.
10-26-2009 12:44 PM
You can use distribute-lists within EIGRP to filter which routes, either outgoing or incoming on an interface, are allowed -
https://www.cisco.com/en/US/docs/ios/12_1/iproute/command/reference/1rdeigrp.html#wp1024147
Jon
10-27-2009 06:33 AM
You are exactly right and I had networks with this very situation and used this solution just fine. Typical of us network folk many others are over complicating the problem and over thinking the solution. Why oh why?
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