RIB failures in BGP (bsci labportfolio lab 6-3)

malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
in CCNP
are rib failures in BGP ALWAYS something that needs to be rectified or just a way of indicating there is a better route?

I'm doing lab 6-3 BGP on the bsci lab portfolio and following it to the word however when I get to section 9 before proceeding I do a sh ip bgp and there are rib failures in the bgp table.

I do however have connectivity and routes being placed in the routing table it's just it doesn't tie up when I do a sh ip bgp to what they illustrate in the book.

Anyone have the same thing on this lab?
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Comments

  • kryollakryolla Member Posts: 785
    whenever I see a RIB failure its because IGP has a better route or sync is turned on but no IGP route
    it's just it doesn't tie up when I do a sh ip bgp to what they illustrate in the book.

    what difference are you seeing
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    kryolla wrote: »
    whenever I see a RIB failure its because IGP has a better route.



    what difference are you seeing

    My bgp table

    Network Next Hop Metric LocPrf Weight Path
    r>i172.16.0.0 172.16.64.1 0 100 0 i
    r>i192.168.1.0/30 192.168.1.5 0 100 0 200 i
    r 192.168.1.1 0 0 200 i
    *>i192.168.1.4/30 192.168.1.5 0 100 0 200 i
    * 192.168.1.1 0 0 200 i
    *>i192.168.100.0 192.168.1.5 0 150 0 200 i
    * 192.168.1.1 0 0 200 i

    bgp table in book

    Network Next Hop Metric LocPrf Weight Path
    *>i172.16.0.0 172.16.64.1 0 100 0 i
    *i192.168.1.0/30 192.168.1.5 0 150 0 200 i
    *> 192.168.1.1 0 0 200 i
    *i192.168.1.4/30 192.168.1.5 0 150 0 200 i
    *> 192.168.1.1 0 0 200 i
    *>i192.168.100.0 192.168.1.5 0 150 0 200 i
    * 192.168.1.1 0 0 200 i

    I've moved onto the next part of the excercise hence why the local preference is changed for some routes and I'm putting it down to some error in the book but the difference in the bgp tables is where my bgp table has r> the table in the book just has *

    Sorry it's a crap description just difficult to put across what I'm on about! Thanks for the reply

    p.s. forgot to mention this is the output from sh iup bgp rib-failure
    SanJose2#sh ip bgp rib-failure
    Network Next Hop RIB-failure RIB-NH Matches
    172.16.0.0 172.16.64.1 Higher admin distance n/a
    192.168.1.0/30 192.168.1.5 Higher admin distance n/a
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  • kryollakryolla Member Posts: 785
    are you suppose to advertise those links via IGP
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    just followed the instructions on the lab man, although you have helped me with one thing! I never had the 172.16.0.0 network advertised into BGP on SanJose2 only in the IGP and now 172.16.0.0 is shopwing in both bgp tables with *> so thanks

    routing as follows I've emboldened what I think are the relevant parts, but can't piece it together. I've been up and studying/working for 15 hours though so maybe missing something blaringly obvious

    ISP
    router bgp 200
    no synchronization
    bgp log-neighbor-changes
    network 192.168.1.0 mask 255.255.255.252
    network 192.168.1.4 mask 255.255.255.252

    These two 192.168 routes are getting the rib failures on SanJose1 & SanJose2...directly connected subnet is ok it's the opposite side of the topology that is getting the rib failure so on SanJose1 it's the 192.168.1.0 /30 and SanJose2 it's the 192.168.1.4 /30 that is showing up with r> for both routes via ibgp and ebgp in the bgp table.

    network 192.168.100.0
    neighbor 192.168.1.2 remote-as 64512
    neighbor 192.168.1.6 remote-as 64512
    no auto-summary


    SanJose1
    router eigrp 64512
    network 172.16.0.0
    no auto-summary
    !
    router bgp 64512
    no synchronization
    bgp log-neighbor-changes
    network 172.16.0.0
    neighbor 172.16.32.1 remote-as 64512
    neighbor 172.16.32.1 update-source Loopback0
    neighbor 172.16.32.1 next-hop-self
    neighbor 192.168.1.5 remote-as 200
    neighbor 192.168.1.5 route-map PRIMARY_IN in
    no auto-summary
    !
    ip http server
    no ip http secure-server
    !
    ip route 172.16.0.0 255.255.0.0 Null0



    SanJose2
    router eigrp 64512
    network 172.16.0.0
    no auto-summary
    !
    router bgp 64512
    no synchronization
    bgp log-neighbor-changes
    network 172.16.0.0 - Just added this in as it was missing and then removed the r> for that route in sh ip bgp cheers icon_cool.gif
    neighbor 172.16.64.1 remote-as 64512
    neighbor 172.16.64.1 update-source Loopback0
    neighbor 172.16.64.1 next-hop-self
    neighbor 192.168.1.1 remote-as 200
    neighbor 192.168.1.1 route-map SECONDARY in
    no auto-summary
    !
    ip route 172.16.0.0 255.255.0.0 Null0
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  • kalebkspkalebksp Member Posts: 1,033 ■■■■■□□□□□
    What do the routing tables look like?

    According to Cisco it's probably caused by another route in the routing table that has a better admin distance. The book may be using an older IOS that doesn't have the rib-failure key.
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  • kryollakryolla Member Posts: 785
    kalebksp wrote: »
    What do the routing tables look like?

    According to Cisco it's probably caused by another route in the routing table that has a better admin distance. The book may be using an older IOS that doesn't have the rib-failure key.

    This usually happens when your IGP and iBGP routers are advertising the same prefix and of course it should choose IGP to route within your AS instead of BGP since BGP is made to route between AS. So hence you get a RIB failure. Remove the 192 network from your IGP this transit link shouldnt be advertised anyway via IGP. Unless you are advertising it to fix the next hop issue since it doesnt change between iBGP peers but you have the next hop self so you dont need to advertise the transit link between eBGP peers
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    kalebksp wrote: »
    What do the routing tables look like?

    According to Cisco it's probably caused by another route in the routing table that has a better admin distance. The book may be using an older IOS that doesn't have the rib-failure key.

    ISP#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

    B 172.16.0.0/16 [20/0] via 192.168.1.6, 01:08:42
    192.168.1.0/30 is subnetted, 2 subnets
    C 192.168.1.0 is directly connected, Serial0/1
    C 192.168.1.4 is directly connected, Serial0/0
    C 192.168.100.0/24 is directly connected, Loopback0


    SanJose1>en
    SanJose1#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

    172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
    D 172.16.32.0/24 [90/2297856] via 172.16.1.2, 02:42:26, Serial0/1
    S 172.16.0.0/16 is directly connected, Null0
    C 172.16.1.0/24 is directly connected, Serial0/1
    C 172.16.64.0/24 is directly connected, Loopback0
    192.168.1.0/30 is subnetted, 2 subnets
    B 192.168.1.0 [20/0] via 192.168.1.5, 01:22:58
    C 192.168.1.4 is directly connected, Serial0/0
    B 192.168.100.0/24 [20/0] via 192.168.1.5, 01:22:58


    SanJose2#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

    172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
    C 172.16.32.0/24 is directly connected, Loopback0
    S 172.16.0.0/16 is directly connected, Null0
    C 172.16.1.0/24 is directly connected, Serial0/1
    D 172.16.64.0/24 [90/2297856] via 172.16.1.1, 02:42:59, Serial0/1
    192.168.1.0/30 is subnetted, 2 subnets
    C 192.168.1.0 is directly connected, Serial0/0
    B 192.168.1.4 [200/0] via 172.16.64.1, 01:23:19
    B 192.168.100.0/24 [200/0] via 172.16.64.1, 01:23:19
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    kryolla wrote: »
    This usually happens when your IGP and iBGP routers are advertising the same prefix and of course it should choose IGP to route within your AS instead of BGP since BGP is made to route between AS. So hence you get a RIB failure. Remove the 192 network from your IGP this transit link shouldnt be advertised anyway via IGP. Unless you are advertising it to fix the next hop issue since it doesnt change between iBGP peers but you have the next hop self so you dont need to advertise the transit link between eBGP peers

    I knew about the IGP beign preferred etc but I posted the config in a previous post and it shows I am not advertising the 192 network in an IGP only the 172.16.0.0 network into EIGRP so that's kinda irrelevant.

    It is advertising 192.168.1.0 & .4 /30 from the ISP in BGP AS 200 to AS 64512. As I said this is the exact lab portfolio config, not something I've made up myself.....The one I made up myself did not have this issue at least which is a positive and it had another 3 routers and redistribution going on! I just wanted to make sure I wasn't doing something crazy or missing something silly.

    Also done traceroutes and the traffic is being routed the correct way with the ISP as the transit network so I'm baffled.

    I'm guessing it's an IOS thing or something, thanks both for responses.
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    Just spotted that one, I had moved onto the next part of the exercise and set the local preference oops sorry guys ***slaps self*** that is why it was learning the route via ibgp as that router had a higher local pref!

    So the routing tables and bgp tables are as follows which I think look correct despite the rib failures still being in there.......comments? cheers

    SanJose1#sh ip bgp
    BGP table version is 9, local router ID is 172.16.64.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    * i172.16.0.0 172.16.32.1 0 100 0 i
    *> 0.0.0.0 0 32768 i
    * i192.168.1.0/30 172.16.32.1 0 100 0 200 i
    *> 192.168.1.5 0 0 200 i
    r i192.168.1.4/30 172.16.32.1 0 100 0 200 i
    r> 192.168.1.5 0 0 200 i
    * i192.168.100.0 172.16.32.1 0 100 0 200 i
    *> 192.168.1.5 0 0 200 i

    SanJose1#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

    172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
    D 172.16.32.0/24 [90/2297856] via 172.16.1.2, 00:09:44, Serial0/1
    S 172.16.0.0/16 is directly connected, Null0
    C 172.16.1.0/24 is directly connected, Serial0/1
    C 172.16.64.0/24 is directly connected, Loopback0
    192.168.1.0/30 is subnetted, 2 subnets
    B 192.168.1.0 [20/0] via 192.168.1.5, 00:01:24
    C 192.168.1.4 is directly connected, Serial0/0
    B 192.168.100.0/24 [20/0] via 192.168.1.5, 00:01:24

    SanJose2#sh ip bgp
    BGP table version is 6, local router ID is 172.16.32.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    *> 172.16.0.0 0.0.0.0 0 32768 i
    * i 172.16.64.1 0 100 0 i
    r> 192.168.1.0/30 192.168.1.1 0 0 200 i
    r i 172.16.64.1 0 100 0 200 i
    *> 192.168.1.4/30 192.168.1.1 0 0 200 i
    * i 172.16.64.1 0 100 0 200 i
    *> 192.168.100.0 192.168.1.1 0 0 200 i
    * i 172.16.64.1 0 100 0 200 i


    anJose2#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

    172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
    C 172.16.32.0/24 is directly connected, Loopback0
    S 172.16.0.0/16 is directly connected, Null0
    C 172.16.1.0/24 is directly connected, Serial0/1
    D 172.16.64.0/24 [90/2297856] via 172.16.1.1, 00:10:25, Serial0/1
    192.168.1.0/30 is subnetted, 2 subnets
    C 192.168.1.0 is directly connected, Serial0/0
    B 192.168.1.4 [20/0] via 192.168.1.1, 00:01:34
    B 192.168.100.0/24 [20/0] via 192.168.1.1, 00:01:34
    SanJose2#
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  • kryollakryolla Member Posts: 785
    I am booting my lab and will lab this

    The transit link between SJ1 and ISP is getting advertised to SJ2 and then back to SJ1 which will not use this route to the AD of the directly connected link so you have a RIB failure. Same thing with SJ2 -> ISP link.

    I also get the same error notice the distance of Zero for the directly connected links
    R5 is ISP, R2 is San Jose 2, and R3 is San Jose 1

    Rack1R5#sh ip bgp
    BGP table version is 10, local router ID is 150.1.5.5
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    * 172.16.0.0 192.168.1.6 0 0 64512 i
    *> 192.168.1.2 0 0 64512 i
    *> 192.168.1.0/30 0.0.0.0 0 32768 i
    *> 192.168.1.4/30 0.0.0.0 0 32768 i
    *> 192.168.100.0 0.0.0.0 0 32768 i
    Rack1R5#

    Rack1R2#sh ip bgp
    BGP table version is 6, local router ID is 172.16.32.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    * i172.16.0.0 172.16.64.1 0 100 0 i
    *> 0.0.0.0 0 32768 i
    r i192.168.1.0/30 192.168.1.5 0 100 0 200 i
    r> 192.168.1.1 0 0 200 i
    * i192.168.1.4/30 192.168.1.5 0 100 0 200 i
    *> 192.168.1.1 0 0 200 i
    * i192.168.100.0 192.168.1.5 0 100 0 200 i
    *> 192.168.1.1 0 0 200 i
    Rack1R2#sh ip bgp rib
    Rack1R2#sh ip bgp rib-failure
    Network Next Hop RIB-failure RIB-NH Matches
    192.168.1.0/30 192.168.1.1 Higher admin distance n/a

    Rack1R2#sh ip route 192.168.1.0 255.255.255.252
    Routing entry for 192.168.1.0/30
    Known via "connected", distance 0, metric 0 (connected, via interface)
    Routing Descriptor Blocks:
    * directly connected, via Serial0
    Route metric is 0, traffic share count is 1

    Rack1R2#

    Rack1R3#sh ip bgp
    BGP table version is 8, local router ID is 172.16.64.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    *> 172.16.0.0 0.0.0.0 0 32768 i
    * i 172.16.32.1 0 100 0 i
    * i192.168.1.0/30 192.168.1.1 0 100 0 200 i
    *> 192.168.1.5 0 0 200 i
    r i192.168.1.4/30 192.168.1.1 0 100 0 200 i
    r> 192.168.1.5 0 0 200 i
    * i192.168.100.0 192.168.1.1 0 100 0 200 i
    *> 192.168.1.5 0 0 200 i

    Rack1R3#sh ip bgp rib
    Network Next Hop RIB-failure RIB-NH Matches
    192.168.1.4/30 192.168.1.5 Higher admin distance n/a

    Rack1R3#sh ip route 192.168.1.4 255.255.255.252

    Routing entry for 192.168.1.4/30
    Known via "connected", distance 0, metric 0 (connected, via interface)
    Routing Descriptor Blocks:
    * directly connected, via Serial1/0
    Route metric is 0, traffic share count is 1

    Rack1R3#
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  • kryollakryolla Member Posts: 785
    Solution do not advertise the transit links and both SJ will have the network that ISP is advertising. There is 2 valid routes to 192.168.100.0. 1 Is best and the second is redundant

    Rack1R2#sh ip bgp
    BGP table version is 11, local router ID is 172.16.32.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    * i172.16.0.0 172.16.64.1 0 100 0 i
    *> 0.0.0.0 0 32768 i
    * i192.168.100.0 192.168.1.5 0 100 0 200 i
    *> 192.168.1.1 0 0 200 i
    Rack1R2#
    terminal-server#2
    [Resuming connection 2 to r3 ... ]

    *A
    Rack1R3#sh ip bgp
    BGP table version is 13, local router ID is 172.16.64.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    *> 172.16.0.0 0.0.0.0 0 32768 i
    * i 172.16.32.1 0 100 0 i
    * i192.168.100.0 192.168.1.1 0 100 0 200 i
    *> 192.168.1.5 0 0 200 i
    Rack1R3#
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    kryolla wrote: »
    Solution do not advertise the transit links and both SJ will have the network that ISP is advertising. There is 2 valid routes to 192.168.100.0. 1 Is best and the second is redundant

    Can you clarify what you mean when you say "do not advertise the transit links"?

    If you mean remove the lines from ISP BGP 200

    network 192.168.1.0 mask 255.255.255.252
    network 192.168.1.4 mask 255.255.255.252

    .....then this just makes the desired routes completely disappear from the BGP table on my config. The network I'm having issues with is not 192.168.100.0 /24 - This network is in BGP, the routing table and no rib errors.

    The issue I have is I get the rib failures on SJ1 & SJ2 only.

    SJ1 subnet directly connected to ISP is 192.168.1.4 /30
    This subnet is advertised into BGP by the ISP router
    This subnet has the rib failures in SJ2 bgp table

    This is the exact opposite on SJ2 where

    SJ2 subnet directly connected to ISP is 192.168.1.0 /30
    This subnet is advertised into BGP by the ISP router
    This subnet has the rib failures in SJ1 bgp table but is reachable

    Do you see where I'm coming from or are we getting our wires crossed here? Sorry if I'm missing something in your explanation
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    This is how the sh ip bgp and sh ip route's look on SJ1 & 2 respectively which looks correct to me so all I want to clarify is should I even care about these rib failures as the routes are in the routing table and being passed via eBGP.
    SanJose1#sh ip route 192.168.1.4
    Routing entry for 192.168.1.4/30
    Known via "connected", distance 0, metric 0 (connected, via interface)
    Routing Descriptor Blocks:
    * directly connected, via Serial0/0
    Route metric is 0, traffic share count is 1

    SanJose1#sh ip route 192.168.1.0
    Routing entry for 192.168.1.0/30, 2 known subnets
    Attached (1 connections)

    B 192.168.1.0 [20/0] via 192.168.1.5, 00:08:39
    C 192.168.1.4 is directly connected, Serial0/0


    SanJose1#sh ip bgp
    BGP table version is 23, local router ID is 172.16.64.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    * i172.16.0.0 172.16.32.1 0 100 0 i
    *> 0.0.0.0 0 32768 i
    * i192.168.1.0/30 172.16.32.1 0 100 0 200 i
    *> 192.168.1.5 0 0 200 i
    r i192.168.1.4/30 172.16.32.1 0 100 0 200 i
    r> 192.168.1.5 0 0 200 i
    * i192.168.100.0 172.16.32.1 0 100 0 200 i
    *> 192.168.1.5 0 0 200 i
    SanJose2>sh ip route 192.168.1.0
    Routing entry for 192.168.1.0/30, 2 known subnets
    Attached (1 connections)

    C 192.168.1.0 is directly connected, Serial0/0
    B 192.168.1.4 [20/0] via 192.168.1.1, 00:09:34

    B 192.168.1.4 [20/0] via 192.168.1.1, 00:09:34
    SanJose2>
    SanJose2>sh ip bgp
    BGP table version is 20, local router ID is 172.16.32.1
    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
    r RIB-failure, S Stale
    Origin codes: i - IGP, e - EGP, ? - incomplete

    Network Next Hop Metric LocPrf Weight Path
    * i172.16.0.0 172.16.64.1 0 100 0 i
    *> 0.0.0.0 0 32768 i
    r i192.168.1.0/30 172.16.64.1 0 100 0 200 i
    r> 192.168.1.1 0 0 200 i
    * i192.168.1.4/30 172.16.64.1 0 100 0 200 i
    *> 192.168.1.1 0 0 200 i
    * i192.168.100.0 172.16.64.1 0 100 0 200 i
    *> 192.168.1.1 0 0 200 i
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  • kryollakryolla Member Posts: 785
    Let me see if I can explain it better. You shouldnt just care if the rib failures affect traffic but you should be concerned on why you are getting it.

    ISP router to SJ2 network 192.168.1.0 mask 255.255.255.252
    ISP router to SJ1 network 192.168.1.4 mask 255.255.255.252

    Follow me so far

    SJ1 get 192.168.1.0 from ISP router
    SJ2 get 192.168.1.4 from ISP router

    SJ1 advertises 192.168.1.0 to SJ2
    SJ2 then makes a decision because he has this network being advertised by BGP and also has it directly connected with an AD of 0. SJ2 ignores the BGP route and now has a RIB failure with a higher AD. BGP internal AD is 200 and directly connected link has an AD of 0.

    SJ2 advertises 192.168.1.4 to SJ1
    SJ1 then makes a decision because he has this network being advertised by BGP and also has it directly connected with an AD of 0. SJ1 ignores the BGP route and now has a RIB failure with a higher AD. BGP internal AD is 200 and directly connected link has an AD of 0.

    The soultion is not to advertise the transit links. BGP only need to advertise networks with the underlying IGP is in charge of getting it to the next hop if it spreads across multiple iBGP peers in the same AS. For eBGP peers it uses the directly connected links and the next hop changes. Now when you start peering with Loopbacks it will use that ip address for the next hop so you have to have reachability to the loopbacks. So whatever method you use, peering with loopbacks or next-hop-self the next hop has to be reachable or else the router will not use it.
    .....then this just makes the desired routes completely disappear from the BGP table on my config. The network I'm having issues with is not 192.168.100.0 /24 - This network is in BGP, the routing table and no rib errors.

    What do you mean desired routes. These are transit links and not networks. You are getting confused with IGP and BGP. BGP is tottaly different beast. With BGP you dont need to put the directly connected link into the routing process unlike IGP. BGP network statement is just to advertise the network unlike IGP.

    One of the questions of the lab portfolio is asking why is the ping failing when you dont source it from a specific network. Do you know the answer?
    This is how the sh ip bgp and sh ip route's look on SJ1 & 2 respectively which looks correct to me so all I want to clarify is should I even care about these rib failures as the routes are in the routing table and being passed via eBGP.
    Yes you should care
    Studying for CCIE and drinking Home Brew
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  • malcyboodmalcybood Member Posts: 900 ■■■□□□□□□□
    I understand about lower AD etc etc.

    I've done a bit of digging around on other sites like groupstudy and people who have asked the same question have gotten a response simply that a route doesn't get entered into the routing table by BGP if there is an entry with a lower AD somewhere else which results in a rib failure in bgp table.

    They do not give any corrective measures, although I did see one person suggest using this command;

    Suppress BGP Advertisement for Inactive Routes [Cisco IOS Software Releases 12.2 S] - Cisco Systems

    I am going to move onto the next lab as I think I'm beginning to dig a deeper hole looking for a more in depth theory that doesn't exist when it is as simple as there is a route with a lower AD available. I think when you do a sh ip rib-failure and it says there is a higher AD in a topology like this there is not any real issue.

    My initial curiosity came from the differing output in the book to my lab environment but I guess these things happen when different IOS' and router models etc come into play.

    Thanks for your time helping me with this kryolla.
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