Median router default route normal behaviour

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- Daniel-G
  
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posted
14 years ago

Sun, May 17, 2009 9:03 PM

Hi to all,

10.60.2.10---- 10.60.2.3 (G0/0) (G0/1) 10.64.2.3 ----- 10.64.2.10

Routers Left and Right announce 10.60 and 10.64 through BGP on the other side. BGP routes are distributes to the Middle router through EIGRP The router in the middle is the default gateway for hosts on subnets

10.60 and 10.64 respectively

on Middle I've set ip route default 0.0.0.0 0.0.0.0 10.60.2.2 ip route default 0.0.0.0 0.0.0.0 10.64.2.2 (tried also to set a metric on the routes, but no change)

And also to have hosts from 10.64.0.0 use 10.64.2.2 I've set a route map

ip access-list extended from1064to1060 permit ip 10.64.0.0 0.0.255.255 10.60.0.0 0.0.255.255 permit ip 10.64.0.0 0.0.255.255 10.200.0.0 0.0.255.255 ip access-list extended from1064toANY deny ip 10.60.0.0 0.0.255.255 any deny ip 10.200.0.0 0.0.255.255 any deny ip 10.64.0.0 0.0.255.255 10.15.0.0 0.0.255.255 deny ip 10.64.0.0 0.0.255.255 10.16.0.0 0.0.255.255 permit ip 10.64.0.0 0.0.255.255 any

route-map toANY-RMAP permit 5 match ip address from1064to1060 set interface GigabitEthernet0/0 ! route-map toANY-RMAP permit 10 match ip address from1064toANY set ip next-hop 10.64.2.2 !

I notice a traceroute go always through 10.60 despite it matches the policy

example : traceroute 195.11.34.97 from 10.64.2.10

10.64.2.3 10.60.2.3 10.64.2.3 10.64.2.2

Any clues ?? Thanks in advance Daniel

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- bod43
  
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posted
14 years ago

Sun, May 17, 2009 10:14 PM

=A0 =A0 Internet

=A0 =A0 | =A0 =A0 =A0 =A0 =A0 =A0 =A0BGP AS600

=A0 +--10.64.2.2 =A0 =A0|

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0| =A0 =A0 =A0 =A0 |

=A0 =A0 =A0 =A0 =A0| =A0 =A0 =A0 Right

I have not studied all of the information that you have presented in full however there are a couple of things that spring to mind.

I have the idea that PBR cannot be applied to traffic originated by the router. So your test traffic will not be PBRed. I have a vague notion that this can be accomplished with recent IOS, maybe? A quick search turns up no results though.

PBR is applied by a policy map applied on the inbound interface, do you have one so applied?

Also:- Next hop interface has no meaning on an ethernet interface. It only has meaning on a point to point interface. Think about what arp entry the router will use to send the traffic to the next hop. On a point to point the router can just send the traffic out the interface since no L2 addresseing is used or needed.

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- Daniel-G
  
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posted
14 years ago

Mon, May 18, 2009 9:57 PM

You're right but here the trafic is originated from another point in the subnet (here the right side router) so PBR should apply

Maybe but this clause is intended for consistency, maybe it's useless

I think the problem is with the 2 static default routes. I've read somewhere that routing is applied in the order the routes are described in case of different metrics, in a kind of round robin with the same metrics. What I want is to force trfic originating from 10.64 to use the default gateway on 10.64 and same for 10.60 with which there is no problem why this route is the first declared

Daniel

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- Dan Lanciani
  
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posted
14 years ago

Tue, May 19, 2009 4:03 AM

| I have the idea that PBR cannot be applied to | traffic originated by the router. So your test traffic will | not be PBRed. I have a vague notion that | this can be accomplished with recent IOS, maybe?

ip local policy route-map

will do this but it can be tricky. Let's say you have an L2TP tunnel terminating on a router with a local policy map. You might think that the local policy would apply to L2TP packets sent, and it does for control packets. But for data packets the map (if any) associated with the interface on which the encapsulated packet was received is used.

Dan Lanciani ddl@danlan.*com