Policy routing

Answered Question
Mar 24th, 2007
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Hello,

I am having a hard time with policy routing.

There is a 1841 router having 2 WAN connections (aDSL), each with different ISP.

What I am trying to do originate traffic from each fastethernet to different dialer an vice versa.

Let's say di0<->fa0/0 & di1<->fa0/1.


Imagine two different LANs, each using its own WAN connection.


Till now I have:


interface FastEthernet0/1

ip address x.y.z.a 255.255.255.248

ip policy route-map ROUTEMAPNAME


access-list 101 permit ip x.y.z.0 0.0.0.7 any


route-map ROUTEMAPNAME permit 1

match ip address 101

set interface dialer1


Thanks in advance

Correct Answer by Richard Burts about 10 years 3 days ago

Stavros


It seems to me that your Policy Based Routing should work with either set interface or set next-hop.


If you want to direct all traffic coming into fa0/0 to go to dialer 0, all traffic coming into fa0/1 to go to dialer 1, all traffic coming into dialer 0 to go to fa0/0 and all traffic coming into dialer 1 to go to fa0/1 then you will need ip policy configured on all 4 interfaces.


While the parts of config that you posted look ok, you have not indicated whether that part is working or not. Perhaps you can clarify.


I would also like to ask a clarifying question: is it possible that a packet could arrive at dialer1 with a destination address on fa0/0? If that did happen what would you do? Your statement of requirements seems to indicate that you would forward it to fa0/1 anyway. Is this an accurate statement of requirements?


There was a discussion in NetPro a while back about something similar to this situation and suggestion made that perhaps VRF lite might be a way to get the results that you want - almost like 2 separate routers in the same box. Perhaps you can think about this alternative.


HTH


Rick

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royalblues Sat, 03/24/2007 - 02:28
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Friend,


Let me know if i understand your requirement here.

You want the traffic from Fa0/1 to exit via Dialer1 and fa 0/0 via dialer0


You should better use the next hop ips in this case.

Configure 2 LAN pools corresponding to the LAN pool.

USe route-maps and instead of set interface use set ip next-hop of the dialer interfaces.


Narayan


akaliptos Sat, 03/24/2007 - 10:15
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I need all traffic originating behind fa0/1 to be routed via dialer1, as well as all inbound traffic to dialer1 to be forwarded to fa0/1.

As if there are 2 routers (di0-fa0/0 & di1-fa0/1).

Correct Answer
Richard Burts Sat, 03/24/2007 - 10:38
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Stavros


It seems to me that your Policy Based Routing should work with either set interface or set next-hop.


If you want to direct all traffic coming into fa0/0 to go to dialer 0, all traffic coming into fa0/1 to go to dialer 1, all traffic coming into dialer 0 to go to fa0/0 and all traffic coming into dialer 1 to go to fa0/1 then you will need ip policy configured on all 4 interfaces.


While the parts of config that you posted look ok, you have not indicated whether that part is working or not. Perhaps you can clarify.


I would also like to ask a clarifying question: is it possible that a packet could arrive at dialer1 with a destination address on fa0/0? If that did happen what would you do? Your statement of requirements seems to indicate that you would forward it to fa0/1 anyway. Is this an accurate statement of requirements?


There was a discussion in NetPro a while back about something similar to this situation and suggestion made that perhaps VRF lite might be a way to get the results that you want - almost like 2 separate routers in the same box. Perhaps you can think about this alternative.


HTH


Rick

akaliptos Sat, 03/24/2007 - 12:12
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Of course!!! On all interfaces, as well as remove the default route (this is what I was missing!)

Thank you, your post "unstuck" me!


Regards,

Stavros

Richard Burts Sat, 03/24/2007 - 12:59
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Stavros


I am glad that my post was able to help you to find the solution to your issue. And thanks for the rating. The forum is a very helpful place to discuss problems and to find solutions. I encourage you to continue your participation in the forum.


HTH


Rick

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