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606 Views 4 Replies Latest reply: May 3, 2012 1:59 AM by DEEPAK ARORA RSS

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Route Redistribution

May 1, 2012 10:59 PM

black-cisco01 96 posts since
May 5, 2010

I was looking at video of a wel know CCIE ( wont mention his name to keep his integrity intact... -_- ) instructor

the subject was about route redistribution. its was redistribution between RIP and OSPF.

he mention that in this case we needed to redistribute also the connected route to have full connectivity.

 

I doubt it what he was saying because i had practice route redistribution before and never had any problems

with connectivity without redistributing the connecting routes. I could see the picture though what he was talking about but because

of former experience i had some doubt so I builded the same lab in gns3 and didn't redistributed the connected route and had full connectivity.

 

R5 could reach R4 and R4 could reach the loopbacks of R5.

 

After this short story here's the question..-__-..... How is it possible that for example R4 could ping the loopbacks of R5 without

redistributing the connected route between R1 and R5...because RIP indeed ( obvious) does not sees that route as an

RIP learned route but as an connected route.

 

If its not to much trouble could some1 provide an example where we should redistribute the connected route to have full connectivy.

 

See the image to have a good picture

 

cheers...

Attachments:
  • borzol CCNP (CCIE R&S candidate) 276 posts since
    Apr 6, 2012
    Currently Being Moderated
    1. May 2, 2012 12:19 AM (in response to black-cisco01)
    Re: Route Redistribution

    hi,

     

    "

    .because RIP indeed ( obvious) does not sees that route as an

    RIP learned route but as an connected route. "

     

    it is the normal behaviour of ospf and rip. when you have connected interfaces, and you advertise those under rip or ospf via network statement (or under interface - ospf) , and then redistrubute rip into ospf and/or ospf into rip the connected interfaces will be redistributed too, because those connected interfaces are rip and/or ospf routes in rip/ospf domains.

     

    I did a little topology:

    top1.png

    And the outputs:

     

    on R2:

    R2#sh ip int brie

    Interface                  IP-Address      OK? Method Status                Protocol

    Serial0/0                  1.1.1.2         YES manual up                    up

    Serial0/1                  2.2.2.2         YES manual up                    up

    Serial0/2                  unassigned      YES unset  administratively down down

    Serial0/3                  unassigned      YES unset  administratively down down

    Loopback1                  11.0.0.1        YES manual up                    up

    Loopback2                  12.0.0.1        YES manual up                    up

    R2#sh ip os int brie

    Interface    PID   Area            IP Address/Mask    Cost  State Nbrs F/C

    Se0/1        1     0               2.2.2.2/24         64    P2P   1/1

    Lo2          1     0               12.0.0.1/24        1     LOOP  0/0

    R2#sh ip rip

    R2#sh ip rip ?

      database  IP RIP database

     

    R2#sh ip rip da

    R2#sh ip rip database

    1.0.0.0/8    auto-summary

    1.1.1.0/24    directly connected, Serial0/0

    2.0.0.0/8    auto-summary

    2.2.2.0/24    redistributed

        [3] via 0.0.0.0,

    11.0.0.0/8    auto-summary

    11.0.0.0/24    directly connected, Loopback1

    12.0.0.0/8    auto-summary

    12.0.0.0/24    redistributed

        [3] via 0.0.0.0,

    R2#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

    C       1.1.1.0 is directly connected, Serial0/0

         2.0.0.0/24 is subnetted, 1 subnets

    C       2.2.2.0 is directly connected, Serial0/1

         11.0.0.0/24 is subnetted, 1 subnets

    C       11.0.0.0 is directly connected, Loopback1

         12.0.0.0/24 is subnetted, 1 subnets

    C       12.0.0.0 is directly connected, Loopback2

    R2#

     

    on R1:

     

    R1#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

    C       1.1.1.0 is directly connected, Serial0/0

         2.0.0.0/24 is subnetted, 1 subnets

    R       2.2.2.0 [120/3] via 1.1.1.2, 00:00:21, Serial0/0

         11.0.0.0/24 is subnetted, 1 subnets

    R       11.0.0.0 [120/1] via 1.1.1.2, 00:00:21, Serial0/0

         12.0.0.0/24 is subnetted, 1 subnets

    R       12.0.0.0 [120/3] via 1.1.1.2, 00:00:21, Serial0/0

    R1#

     

    on R3:

     

    R3#sh ip route os

         1.0.0.0/24 is subnetted, 1 subnets

    O E2    1.1.1.0 [110/20] via 2.2.2.2, 00:01:30, Serial0/0

         11.0.0.0/24 is subnetted, 1 subnets

    O E2    11.0.0.0 [110/20] via 2.2.2.2, 00:01:30, Serial0/0

         12.0.0.0/32 is subnetted, 1 subnets

    O       12.0.0.1 [110/65] via 2.2.2.2, 00:03:44, Serial0/0

    R3#

    R3#

    R3#

    R3#sh ip route os

         1.0.0.0/24 is subnetted, 1 subnets

    O E2    1.1.1.0 [110/20] via 2.2.2.2, 00:02:54, Serial0/0

         11.0.0.0/24 is subnetted, 1 subnets

    O E2    11.0.0.0 [110/20] via 2.2.2.2, 00:02:54, Serial0/0

         12.0.0.0/32 is subnetted, 1 subnets

    O       12.0.0.1 [110/65] via 2.2.2.2, 00:05:08, Serial0/0

    R3#

     

    On R2 I don't redistribute connected interfaces (serial and loopbacks), but on r1 and r3 these are appear.

     

    R2 config:

     

    !

    !

    interface Loopback1

    description rip connected

    ip address 11.0.0.1 255.255.255.0

    !

    interface Loopback2

    description ospf conn

    ip address 12.0.0.1 255.255.255.0

    ip ospf 1 area 0

    !

    interface Serial0/0

    ip address 1.1.1.2 255.255.255.0

    serial restart-delay 0

    !

    interface Serial0/1

    ip address 2.2.2.2 255.255.255.0

    ip ospf 1 area 0

    serial restart-delay 0

    !

    interface Serial0/2

    no ip address

    shutdown

    serial restart-delay 0

    !

    interface Serial0/3

    no ip address

    shutdown

    serial restart-delay 0

    !

    router ospf 1

    log-adjacency-changes

    redistribute rip subnets

    !

    router rip

    version 2

    redistribute ospf 1 metric 3

    network 1.0.0.0

    network 11.0.0.0

    no auto-summary

    !

     

    I hope this is the answer you are looking for.

     

    regards,

     

    borzol

  • borzol CCNP (CCIE R&S candidate) 276 posts since
    Apr 6, 2012
    Currently Being Moderated
    3. May 2, 2012 1:35 AM (in response to black-cisco01)
    Re: Route Redistribution

    hi,

    I agree with you, I don't think it is necessary too.

     

    Maybe just when you don't advertise your connected routes into routing protocolls. (?)

     

    borzol

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