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How to change AD value during redistribution

Unanswered Question
Dec 9th, 2013
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Please help me!!!!!


Please find below diagram. Between R7 and R1 RIPV2 is running, Between R1,R2,R3,R4 EIGRP is running and R3,R4,R5,R6 OSPF is running. I have redistributed RIP into EIGRP and vice versa at R1. At R3 and R4 redistributed EIGRP and OSPF vice versa.


PROBLEM:


I am getting a loop while trying to ping from R7 to R5'S loopback interface. Reply packet is getting looped at R3. Please find below Show ip route at R3.


3#sh ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route


Gateway of last resort is not set


     1.0.0.0/24 is subnetted, 1 subnets

D       1.1.1.0 [90/156160] via 30.1.1.1, 00:01:59, FastEthernet1/0

     50.0.0.0/24 is subnetted, 1 subnets

C       50.1.1.0 is directly connected, FastEthernet0/0

     2.0.0.0/24 is subnetted, 1 subnets

D       2.2.2.0 [90/412160] via 30.1.1.1, 00:01:59, FastEthernet1/0

     70.0.0.0/24 is subnetted, 1 subnets

O       70.1.1.0 [110/20] via 50.1.1.2, 00:01:59, FastEthernet0/0

     3.0.0.0/24 is subnetted, 1 subnets

C       3.3.3.0 is directly connected, Loopback1

     4.0.0.0/24 is subnetted, 1 subnets

D       4.4.4.0 [90/437760] via 30.1.1.1, 00:01:17, FastEthernet1/0

     80.0.0.0/24 is subnetted, 1 subnets

O E1    80.1.1.0 [110/45] via 50.1.1.2, 00:02:02, FastEthernet0/0

     20.0.0.0/24 is subnetted, 1 subnets

D       20.1.1.0 [90/309760] via 30.1.1.1, 00:01:18, FastEthernet1/0

     5.0.0.0/32 is subnetted, 1 subnets

O       5.5.5.5 [110/11] via 50.1.1.2, 00:02:02, FastEthernet0/0

     6.0.0.0/32 is subnetted, 1 subnets

O       6.6.6.6 [110/21] via 50.1.1.2, 00:02:02, FastEthernet0/0

     7.0.0.0/24 is subnetted, 1 subnets

O E1    7.7.7.0 [110/45] via 50.1.1.2, 00:02:02, FastEthernet0/0

     40.0.0.0/24 is subnetted, 1 subnets

D       40.1.1.0 [90/312320] via 30.1.1.1, 00:01:18, FastEthernet1/0

     10.0.0.0/24 is subnetted, 1 subnets

D       10.1.1.0 [90/284160] via 30.1.1.1, 00:02:02, FastEthernet1/0

     90.0.0.0/24 is subnetted, 1 subnets

C       90.1.1.0 is directly connected, FastEthernet2/0

     60.0.0.0/24 is subnetted, 1 subnets

O       60.1.1.0 [110/30] via 50.1.1.2, 00:02:02, FastEthernet0/0

     30.0.0.0/24 is subnetted, 1 subnets

C       30.1.1.0 is directly connected, FastEthernet1/0


R3 is getting the 80.1.1.0/24 from OSPF i.e R5, In which R7 packet is getting Looped. Please provide me some solution So that I can get a Loop free path. Is there any mechanism to increase the metric at R4 during redistribution. So that R3 will directly forward the packet to R1.


xxxxxxx.png



Thanks & Regards,

Sanjib Pradhan

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John Blakley Mon, 12/09/2013 - 05:45
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  • Purple, 4500 points or more

In a topology like this, you're going to want to tag the routes at the redistribution points. You'll deny that tag from being redistributed back into itself. For example:


route-map OSPF-Rip deny 10

match tag 120

route-map OSPF-Rip permit 20

set tag 110


router rip

redistribute ospf 1 metric 15 route-map OSPF-Rip


route-map Rip-OSPF deny 10

match tag 110

route-map Rip-OSPF permit 20

set tag 120


router ospf 1

redistribute rip subnets route-map Rip-OSPF


What the above does (OSPF route-map) is tag the RIP traffic that's being redistributed into OSPF as 120 (the RIP AD just to keep it simple). We know thow the routes got into OSPF and that was redistributing them from RIP, so RIP already knows about them. We don't want to redistribute these new OSPF routes into RIP, so we have to match that tag (120) when redistributing OSPF into RIP which explains the first route map.



HTH,
John

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