From: Carlos Alberto Trujillo Jimenez (carlos.trujillo.jimenez@gmail.com)
Date: Fri Mar 07 2008 - 16:38:44 ARST
Jorge.
Im using Software (C2800NM-ADVENTERPRISEK9-M), Version 12.4(8a) in my test.
One interesting command I found in the same page I send you in the last
mail... the link is redirecting to a cisco web page:
http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fs_sbair.html
the command "bgp
suppress-inactive"<http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fs_sbair.html#wp1027385>
under
bgp address family ipv4 states:
Configures a router to suppress the advertisement of BGP routes that are not
installed into the Routing Information Base (RIB) and Forwarding Information
Base (FIB) tables.
In my example I added the following configuration to router 2:
router bgp 65001
address-family ipv4
bgp suppress-inactive
After that, I cleared the bgp session, (not only the soft clearing, I
cleared also the bgp session too).
Then I do the following commands in R2, ans I can see completely different
information before adding the command "bgp suppress-inactive" under the ipv4
address family.
r2#show ip bgp 7.7.7.0
BGP routing table entry for 7.7.7.0/24, version 10
Paths: (2 available, best #2, table Default-IP-Routing-Table,
RIB-failure(17) - next-hop mismatch)
Not advertised to any peer
(65000) 700
172.16.10.4 from 172.16.10.4 (172.16.104.1)
Origin IGP, metric 0, localpref 100, valid, confed-external
(65000) 700
172.16.10.3 from 172.16.10.1 (172.16.101.1)
Origin IGP, metric 0, localpref 100, valid, confed-internal, best
Now the prefix is NOT ADVERTISED to any prefix, contrary to the same output
of the same show command before adding the "bgp suppress-inactive" where it
was advertising the prefix, to its neighbors, now it DOES NOT.
r2#show ip bgp neighbors 172.16.25.5 advertised-routes
BGP table version is 14, local router ID is 172.16.102.1
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
*>i0.0.0.0 172.16.10.3 0 100 0 (65000) 700 i
Total number of prefixes 1
r2#
Finally in router 5 the prefix now is not present in the bgp table:
r5#show ip bgp
BGP table version is 6, local router ID is 172.16.105.1
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
*> 0.0.0.0 172.16.25.2 0 100 700 i
r5#
As a conclusion seems that "rib-failure" routes are advertised unless you
prevent them using the commands:
address-family ipv4
bgp suppress-inactive
You are using IOS version 12.2. try using a IOS version 12.4 to see the
different results we are having, Im tryng to get a
2008/3/7, Vazquez, Jorge <Jorge.Vazquez@acs-inc.com>:
>
> I am using version 12.2(44), your link is mentioning something about the
> IOS version may make the router stop advertising those routes.
>
>
>
> *Jorge *
> ------------------------------
>
> *From:* Carlos Alberto Trujillo Jimenez [mailto:
> carlos.trujillo.jimenez@gmail.com]
> *Sent:* Friday, March 07, 2008 11:07 AM
> *To:* Vazquez, Jorge
> *Cc:* ccie forum
> *Subject:* Re: BGP Table on the Lab Exam
>
>
>
> Well, I labbed it, and in my lab topology it works fine.
>
> The router is advertising the bgp prefix to its ebgp peer.
>
>
>
> look, at the results from the router who has the "rib-faiulre" for the
> prefix 7.7.7.0 in the bgp table
>
>
>
> r2#show ip bgp
> BGP table version is 1310, local router ID is 172.16.102.1
> 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
> *> 0.0.0.0 172.16.10.4 0 100 0 (65000) 700 i
> r> 7.7.7.0/24 172.16.10.4 0 100 0 (65000) 700 i
>
> r2#show ip bgp rib-failure
> Network Next Hop RIB-failure RIB-NH
> Matches
> 7.7.7.0/24 172.16.10.4 Higher admin distance
> Yes
> r2#show ip bgp 7.7.7.0
> BGP routing table entry for 7.7.7.0/24, version 1316
> Paths: (1 available, best #1, table Default-IP-Routing-Table,
> RIB-failure(17))
> Advertised to update-groups:
> 1 3
> (65000) 700
> 172.16.10.4 from 172.16.10.4 (172.16.104.1)
> Origin IGP, metric 0, localpref 100, valid, confed-external, best
>
> Router 2 is EBGP-PEERING with R5 and is also ADVERTISING prefix 7.7.7.0/24
>
>
> r2#show ip bgp neighbors 172.16.25.5 advertised-routes
> BGP table version is 1317, local router ID is 172.16.102.1
> 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
> *> 0.0.0.0 172.16.10.4 0 100 0 (65000) 700 i
> r> 7.7.7.0/24 172.16.10.4 0 100 0 (65000) 700 i
>
> Total number of prefixes 2
> r2#
>
>
>
> In router 5, I can see the prefix 7.7.7.0 is present in the bgp table.
>
>
>
> r5#show ip bgp
> BGP table version is 3, local router ID is 172.16.105.1
> 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
> *> 0.0.0.0 172.16.25.2 0 100 700 i
> *> 7.7.7.0/24 172.16.25.2 0 100 700 i
>
> I found other sources that talk about the propagation of "rib-failure"
> prefixes under bgp.
>
> and as in my lab it is working. let me see if can see another example of
> when a rib-failure network is not propagated.
>
>
>
> http://ioshints.blogspot.com/2007/12/what-is-bgp-rib-failure.html
>
>
>
>
>
> Another question. did you lab it and get the results?
>
> <http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fs_sbair.html>
>
>
>
> 2008/3/7, Vazquez, Jorge <Jorge.Vazquez@acs-inc.com>:
>
> Please check this link, it says the routes are not advertised.
>
>
>
> http://www.cisco.com/warp/public/459/bgpfaq_5816.shtml#twenty-three
>
>
>
> *Jorge*
> ------------------------------
>
> *From:* Carlos Alberto Trujillo Jimenez [mailto:
> carlos.trujillo.jimenez@gmail.com]
> *Sent:* Friday, March 07, 2008 10:18 AM
>
>
> *To:* Vazquez, Jorge
> *Cc:* ccie forum
> *Subject:* Re: BGP Table on the Lab Exam
>
>
>
> Jorge, it is not correct.
>
> If you have routes in the BGP table under RIB-failure, those router are
> ADVERTISED to is peer routers via bgp.
>
>
>
> In my example router 2 and router 5 are peering via bgp.
>
> Router 2 has the "RIB-FAILURE" for the prefix 7.7.7.0/24 because the same
> prefix via learned via ospf.
>
>
>
> r2#show ip bgp
> BGP table version is 1309, local router ID is 172.16.102.1
> 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
> *> 0.0.0.0 172.16.10.4 0 100 0 (65000) 700 i
> r> 7.7.7.0/24 172.16.10.4 0 100 0 (65000) 700 i
>
> r2#show ip route ospf
> O E2 7.7.7.0 [110/1] via 172.16.10.4, 03:54:12, Serial0/0/0
>
>
>
> Now you form an EBGP-PEERING between router and and router 5 and check the
> bgp table of router 5 to see if it is learning via bgp the prefix 7.7.7.0.
>
>
>
> r5#show ip bgp
> BGP table version is 3, local router ID is 172.16.105.1
> 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
> *> 7.7.7.0/24 172.16.25.2 0 100 700 i
>
>
>
>
>
> The prefix is present.
>
>
>
>
>
>
>
> 2008/3/7, Vazquez, Jorge <Jorge.Vazquez@acs-inc.com>:
>
> But, I think if you have some routes in the BGP table under RIB-failure,
> those routes are not advertised to the neighbors. So you may not have full
> reachability.
>
>
>
> *Jorge*
> ------------------------------
>
> *From:* Carlos Alberto Trujillo Jimenez [mailto:
> carlos.trujillo.jimenez@gmail.com]
> *Sent:* Friday, March 07, 2008 6:52 AM
> *To:* Vazquez, Jorge
> *Cc:* ccie forum
> *Subject:* Re: BGP Table on the Lab Exam
>
>
>
> Jorge.
>
>
>
> Adding one more thing.
>
>
>
> The presence of a rib-failure and the removing of that, depends of what is
> asked to do in the question.
>
>
>
> If the question states FULL REACHABILITY with rib-failure works fine.
>
> but if the question states PRESENT IN THE ROUTING TABLE VIA BGP. You may
> adjust some configurations as stated in my last mail, to let it work.
>
>
>
> 2008/3/7, Carlos Alberto Trujillo Jimenez <
> carlos.trujillo.jimenez@gmail.com>:
>
> Hi Jorge.
>
>
>
> A Rib Failure happens when a prefix is present in the bgp table, as well
> as in the routing, means the router recibes the same prefix via IBGP as well
> as ANY IGP (OSPF, RIP, EIGRP).
>
> According to the administrative distance ANY IGP is prefered over any IBGP
> ROUTE. Thats why the route is still present in the routing table, but
> learned via any of the IGP you are using in your network.
>
>
>
> If you have a RIB-FAILURE you can test it and it must work fine, you must
> have reachability to that prefix.
>
>
>
> From the BGP point of view, that route present in the bgp table (as
> RIB-FAILURE) is still propagated via bgp to its neighbors.
>
>
>
> if you want to remove the RIB-FAILURE in your bgp table you may adjust the
> ADMIN DISTANCE of the IGP to be higher than the IBGP or may REDUCE the IBGP
> admin distance to be lower than the IGP.
>
>
>
>
>
>
> cheers.
>
>
> 2008/3/7, Vazquez, Jorge <Jorge.Vazquez@acs-inc.com>:
>
> Any advice or comment about this? I would like to know what is correct
> solution when a RIB-failure appears, cause trying to fix that may impact
> the
> routing in all the network topology and maybe it may not be necessary.
>
>
>
> Jorge
>
> _____
>
> From: Vazquez, Jorge
> Sent: Thursday, March 06, 2008 10:29 AM
> To: ccie forum
> Subject: BGP Table on the Lab Exam
>
>
>
> I have completed some IE labs in the last days, I have one question about
> the BPG table, in case I get some routes with RIB-failure, do I have to
> fix
> that or is that ok to have some routes on RIB-failure?
>
>
>
> Regards,
>
>
>
> Jorge
>
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