Howto Show RIB and FIB ?

Discussion in 'Cisco' started by frederic.metz@gmail.com, Mar 18, 2007.

  1. Guest

    Hi all,

    I'm currently looking for a command on the Cisco to see the FIB and
    RIB.

    The "show ip route" command only displays the FIB. I made two static
    entries in the RIB for the same net reached on two different
    interfaces with different metrics. How can I see the actual RIB ? I
    don't want to see the config file, I know that this is a way to find
    it out, but thats not the point for me.

    Cheers,
    Frédéric

    P.S.:
    ----> Entries in config file
    ip route 10.0.0.0 255.0.0.0 Serial0 30
    ip route 10.0.0.0 255.0.0.0 Ethernet0 40
     
    , Mar 18, 2007
    #1
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  2. You got it backwards.

    RIB - show ip route
    FIB - show ip cef, show adj


    wrote:
    > Hi all,
    >
    > I'm currently looking for a command on the Cisco to see the FIB and
    > RIB.
    >
    > The "show ip route" command only displays the FIB. I made two static
    > entries in the RIB for the same net reached on two different
    > interfaces with different metrics. How can I see the actual RIB ? I
    > don't want to see the config file, I know that this is a way to find
    > it out, but thats not the point for me.
    >
     
    Todd Sinclair, Mar 18, 2007
    #2
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  3. Merv Guest


    >
    > > I made two static
    > > entries in the RIB for the same net reached on two different
    > > interfaces with different metrics. How can I see the actual RIB ? I
    > > don't want to see the config file,


    Installed routing entries from RIB seen via sh ip route.

    AFAIK there is no command in IOS to see "backup" routes (i.e the
    static route with admin distance = 40
     
    Merv, Mar 18, 2007
    #3
  4. Guest

    Thanks for the help,

    but Cisco Express forwarding seems a special Forwarding Thing in Cisco
    Routers. It is turned off on my Cisco ("%CEF not running" on both of
    your commands).

    So the RIB is the Table which is build up by Routing Protocols or
    static Routes. It could have the same entry for reaching one network
    with the corresponding metrics. The FIB has only one entry per
    network, the FIB is gerated (as a subset) by the RIB, the FIB tuples
    are unique. --> the "sh ip route" command has only one entry for the
    destination network, so it is the forwarding table (from the FIB). I
    see many people saying "Routing table" when they talk about the
    forwarding table. But I'am a bit abroad this moment.

    I want to see the both tables. sh ip route is the one, how can I see
    the other. CEF is not enabled. The 2 entries are in the config and
    they work.

    ///// S 10.0.0.0/8 is directly connected, Serial0

    after pluggin' out the serial cable, the FIB is new calculated, it
    takes abut 10 seconds and then:

    ///// S 10.0.0.0/8 is directly connected, Ethernet0

    So where the hell is the RIB ? :)

    Thanks and cheers ,,
    Frédéric


    On 18 Mrz., 20:27, Todd Sinclair <> wrote:
    > You got it backwards.
    >
    > RIB - show ip route
    > FIB - show ip cef, show adj
    >
    > wrote:
    > > Hi all,

    >
    > > I'm currently looking for a command on the Cisco to see the FIB and
    > > RIB.

    >
    > > The "show ip route" command only displays the FIB. I made two static
    > > entries in the RIB for the same net reached on two different
    > > interfaces with different metrics. How can I see the actual RIB ? I
    > > don't want to see the config file, I know that this is a way to find
    > > it out, but thats not the point for me.
     
    , Mar 18, 2007
    #4
  5. John Agosta Guest

    <> wrote in message
    news:...
    Thanks for the help,

    but Cisco Express forwarding seems a special Forwarding Thing in Cisco
    Routers. It is turned off on my Cisco ("%CEF not running" on both of
    your commands).

    So the RIB is the Table which is build up by Routing Protocols or
    static Routes. It could have the same entry for reaching one network
    with the corresponding metrics. The FIB has only one entry per
    network, the FIB is gerated (as a subset) by the RIB, the FIB tuples
    are unique. --> the "sh ip route" command has only one entry for the
    destination network, so it is the forwarding table (from the FIB). I
    see many people saying "Routing table" when they talk about the
    forwarding table. But I'am a bit abroad this moment.

    I want to see the both tables. sh ip route is the one, how can I see
    the other. CEF is not enabled. The 2 entries are in the config and
    they work.

    ///// S 10.0.0.0/8 is directly connected, Serial0

    after pluggin' out the serial cable, the FIB is new calculated, it
    takes abut 10 seconds and then:

    ///// S 10.0.0.0/8 is directly connected, Ethernet0

    So where the hell is the RIB ? :)


    The routing table - show ip route - is your FIB. (forwarding based upon
    'best' pathways)

    There is no command that explicitly shows the RIB, which is the collection
    of all routing information learned. (best - worst - and in between pathways)

    You can indirectly learn what is in the RIB by debuging and looking at
    topology data bases.

    For instance, you can debug rip and see what each of your neighbors is
    advertising to you.
    Or, you can look at the OSPF data base and try to interpret its contents.
    But there is no single command that tells you "these are all the pathways
    that I have learned from all neighbors,"
    with the exception of the BGP table, which is essentially a RIB data base.
    (show ip bgp)

    -ja
     
    John Agosta, Mar 18, 2007
    #5
  6. Guest

    Okay, thanks a lot.



    On 18 Mrz., 21:27, "John Agosta" <j_agosta@remove_wideopenwest.kom>
    wrote:
    > <> wrote in message
    >
    > news:...
    > Thanks for the help,
    >
    > but Cisco Express forwarding seems a special Forwarding Thing in Cisco
    > Routers. It is turned off on my Cisco ("%CEF not running" on both of
    > your commands).
    >
    > So the RIB is the Table which is build up by Routing Protocols or
    > static Routes. It could have the same entry for reaching one network
    > with the corresponding metrics. The FIB has only one entry per
    > network, the FIB is gerated (as a subset) by the RIB, the FIB tuples
    > are unique. --> the "sh ip route" command has only one entry for the
    > destination network, so it is the forwarding table (from the FIB). I
    > see many people saying "Routing table" when they talk about the
    > forwarding table. But I'am a bit abroad this moment.
    >
    > I want to see the both tables. sh ip route is the one, how can I see
    > the other. CEF is not enabled. The 2 entries are in the config and
    > they work.
    >
    > ///// S 10.0.0.0/8 is directly connected, Serial0
    >
    > after pluggin' out the serial cable, the FIB is new calculated, it
    > takes abut 10 seconds and then:
    >
    > ///// S 10.0.0.0/8 is directly connected, Ethernet0
    >
    > So where the hell is the RIB ? :)
    >
    > The routing table - show ip route - is your FIB. (forwarding based upon
    > 'best' pathways)
    >
    > There is no command that explicitly shows the RIB, which is the collection
    > of all routing information learned. (best - worst - and in between pathways)
    >
    > You can indirectly learn what is in the RIB by debuging and looking at
    > topology data bases.
    >
    > For instance, you can debug rip and see what each of your neighbors is
    > advertising to you.
    > Or, you can look at the OSPF data base and try to interpret its contents.
    > But there is no single command that tells you "these are all the pathways
    > that I have learned from all neighbors,"
    > with the exception of the BGP table, which is essentially a RIB data base.
    > (show ip bgp)
    >
    > -ja
     
    , Mar 18, 2007
    #6
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