RIPv2 Reliable Conditional Default Routing

Greetings,

I'm working on this lab and having trouble wrapping my head around the concept. Why the static route to a bogus network?

 

I miss be missing something but cant get it.

 

Any suggestions for study materials on this?

 

Thank you in advance!


Debbie

Comments

  • JoeMJoeM ✭✭✭

    Why the static route to a bogus network?

    Maybe think of it as a place-holder.   It is a "dummy route".  

    In order to understand the idea for this particular solution, it is necessary to break it down into blocks.

    1.  RIP Processs conditionally advertises a default route (based on a route-map)

    2.  Route-Map  is good (true) if there is a match to a specific routing-table entry (identified by a prefix-list).

    3.  The RIB entry will exist via a conditional static route.

    4.  The Static Route (for the RIB) is dependent on tracking an SLA (true).

    5.  The SLA pings BB3.

     

     

  • Hi, 

               Just to clarify something. Route-maps only work/are (true) only if a route is installed in the RIB?   

     

    Thanks

    V/R 

    Paul 

  • JoeMJoeM ✭✭✭

    In this scenario, in order for the address/prefix MATCH to be true, it must exist in the RIB. If the MATCH exists, then the default route will be created (originate).

    But route-maps can be used for many things, including matching incoming route updates or attributes (and/or setting attributes).

  • Thank you very much JoeM. 

  • JoeMJoeM ✭✭✭

    Glad that it helped.   As I remember the workbook progession, there is a lot of practice with route-maps in the BGP section.  Soon it will become 2nd nature.

  • I can't wrap my head around why this approach doesn't function as expected:

    R1#show run | s track|rip|sla|route-map

    track 1 ip sla 1

    router rip

     version 2

     network 150.1.0.0

     network 155.1.0.0

     default-information originate route-map RM_R7_VL7

     no auto-summary

    ip sla 1

     icmp-echo 155.1.7.7

     frequency 5

    ip sla schedule 1 life forever start-time now

    route-map RM_R7_VL7 permit 10

     match track  1

    R1#

    This is on CSR1000v running 03.13.02.S

    The track object is working correctly. When i shutdown the interface with the IP 155.1.7.7, the track state goes from UP --> Down. The route-map seems to support using a track object in a match statement. However the router advertises a default route no matter the track object state. 

    I'm assuming this is a bug. Or is that an invalid use of a match in a route-map?

  • Generally, the syntax is 

    match ----- prefix

    set --------- interface.

     

    I'm not sure other matches are supported.

  • For me it is the other way around

    Regardless of whether 155.1.7.7 is reachable or not, there will be no default route sent.

    Oli

  • For me it is the other way around

    Regardless of whether 155.1.7.7 is reachable or not, there will be no default route sent.

     

    Oli

  • aha, I see.  Have to learn about using the ieoc!

     

    oli

  • The problem you're facing is that your route-map is referencing the track object 1 which is wrong. The track object is meant to be referenced by a bogus route that'll act as a place holder in the route-map. For example you'll have:

    ip route 127.0.0.1 255.255.255.255 null0 track 1

     

    As long as the track is UP, the static route will be in the routing table. You'll then create a standard acl with matches the static route like:

    ip access-list standard PLACEHOLDER permit 127.0.0.1 255.255.255.255

     

    Now the route-map that goes on the default-information command will reference the ACL

    route-map CONDITION permit 10

    match ip address PLACEHOLDER 

    !

    router rip

    default-information originate route-map CONDITION

     

    Regards

    Mayowa 

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