[nsp] SAA RTR and Track Commands

[Bruce Pinsky]

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Cho, David wrote:

| Hi All,
|
| I am exploring the option to use SAA command set on 2621 routers but it
| seems unsupported at least the track portion of it.  I've checked the CCO
| but there was no 12.3(4)T image(required according to DOC) available for
| Cisco 2621.  What would you suggest to redistribute static routes to two
| different routers which runs ospf on one interface and static on the other?
| If SAA works on this case, it would have been the best way to do it.
| Obviously, I'd want to avoid the black hole here.  Please see below.
|

Feature Navigator claims it is supported on 2621XM not the 2621 in 12.3(8)T.


|
|      OSPF  - R1 - Static to WAN site ------
|                                           |
|                                           |--- HSRP ---- R3
|                                           |
|      OSPF  - R2 - Static to WAN site ------
|
| R1 is the primary and R2 is the back up.  If the Ethernet interface of R1 to
| R3 fails, I want static redistribution to R1 to stop but R2 static
| redistribution takes over.  I've set the metric on R1 and R2 so that R1's
| redistributed static route has the preference over R2.
|

If you are only concerned about the Ethernet interface of R1 going down
(and similarly on R2), then point the static at the Ethernet interface like:

	ip route 192.168.1.0 255.255.255.0 Ethernet2/2

If that interface goes down, the route will be withdrawn and no longer
redist'd into BGP.

You might also be able to use conditional route advertisements in BGP to
generate the /24 only if the /25 is present.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t4/ftbgpri.htm

|
| Sample Configuration:
| Initial configuration of Customer Router1:
| interface Serial0/1
| ip address 192.168.2.1 255.255.255.252
| interface Ethernet2/2
| ip address 192.168.1.1 255.255.255.128
| standby ip 192.168.1.3
| router bgp 65501
| redistribute static
| -> advertise static routes via BGP neighbor 192.168.2.2 remote-as 65500
| ip route 192.168.1.0 255.255.255.0 Null0
| -> static route for the whole class C -- more specific route will be used to
| forward packets.
| Now, modify the config to only advertise 192.168.1.0/24 via BGP if the
| server
| (192.168.1.4) is reachable by this router.
| Step 1: Configure an SAA probe to ping the server.
| rtr 1
| type echo protocol ipIcmpEcho 192.168.1.4
| rtr schedule 1 life forever start-time now
| Step 2: Create a tracked object and associate the object with the SAA probe
| that was
| previously configured.
| track 123 rtr 1 reachability
| Step 3: Remove the existing static route.
| no ip route 192.168.1.0 255.255.255.0 Null0
| Then configure a static route for the prefix to be advertised via BGP, and
| associate the
| route with the tracked object.
| ip route 192.168.1.0 255.255.255.0 Null0 track 123
| The above changes remove the static route when the server is not reachable.
| This
| guarantees that 192.168.1.0/24 will only be advertised via BGP if the server
| is reachable
| from this router, thus preventing black-holing of packets.
| _______________________________________________
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bep

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