Reliable Static Routing Backup Using Object Tracking

Unanswered Question
Aug 25th, 2008

To configure a reliable static backup route between two routers we control.

Both RTR IOS are same at 12.4.x

1. The wirless is the primary link (Uses FastEth0/x) on both RTR 1 and 2

2. The T1 is secondary (Uses Serial0/0/0:x) on both RTR 1 and 2

3. Wb 1 (wireless bridge) is the icmp object for RTR2

4. Wb 2 (wireless bridge) is the icmp object for RTR1

We have not been successful in getting this to work.

RTR 2 Config (pulled from the above document and modified for our environment).

ip sla monitor 1

type echo protocol ipIcmpEcho x.x.x.x (WB1)

timeout 1000

threshold 2

frequency 3

ip sla monitor schedule 1 life forever start-time now

track 123 rtr 1 reachability

Interface FastEthernet0/1

description Connected to Wireless Bridge 2

ip address x.x.x.x x.x.x.x

no ip route-cache cef

no ip route-cache

duplex auto

speed auto

!

interface Serial0/0/0:1

description T1

ip address x.x.x.x x.x.x.x

no ip route-cache cef

no ip route-cache

!

ip local policy route-map MY-LOCAL-POLICY

ip route x.x.x.x x.x.x.x FastEthernet0/1 track 123 - Route out to RTR1 VLANx subnet

ip route x.x.x.x x.x.x.x FastEthernet0/1 track 123 - Route out to RTR1 VLANx subnet

ip route x.x.x.x x.x.x.x FastEthernet0/1 track 123 - Route out to RTR1 VLANx subnet

ip route x.x.x.x x.x.x.x x.x.x.x - Route out to internet

ip route x.x.x.x x.x.x.x Serial0/0/0:1 254 - Desired Backup Route to RTR VLANx subnet

ip route x.x.x.x x.x.x.x Serial0/0/0:1 254 - Desired Backup Route to RTR VLANx Subnet

ip route x.x.x.x x.x.x.x Serial0/0/0:1 254 - Desired Backup Route to RTR VLANs Subnet

access-list 101 permit icmp any host x.x.x.x echo (WB1)

route-map MY-LOCAL-POLICY permit 10

match ip address 101

*1 set ip next-hop x.x.x.x

*2 set interface Null0

*1 According to the document referenced above you should set this to the IP of the next hop for the primary/tracked route which in this case should be the

FastEth0/1 interface on RTR1

*2 Whenever I set this command I get this WARNING: %Warning:Use P2P interface for routemap

set interface clause

It appears to take the command anyway.

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RTR 2 Config (pulled from the above document and modified for our environment).

ip sla monitor 1

type echo protocol ipIcmpEcho x.x.x.x (WB2)

timeout 1000

threshold 2

frequency 3

ip sla monitor schedule 1 life forever start-time now

track 123 rtr 1 reachability

Interface FastEthernet0/1

description Connected to Wireless Bridge 1

ip address x.x.x.x x.x.x.x

no ip route-cache cef

no ip route-cache

duplex auto

speed auto

!

interface Serial0/0/0:1

description T1

ip address x.x.x.x x.x.x.x

no ip route-cache cef

no ip route-cache

!

ip local policy route-map MY-LOCAL-POLICY

ip route x.x.x.x x.x.x.x FastEthernet0/1 track 123 - All Traffic to RTR 2

ip route x.x.x.x x.x.x.x Serial0/0/0:1 254 - Desired Backup Route to RTR 2

access-list 101 permit icmp any host x.x.x.x echo (WB2)

route-map MY-LOCAL-POLICY permit 10

match ip address 101

*1 set ip next-hop x.x.x.x

*2 set interface Null0

*1 According to the document referenced above you should set this to the IP of the next hop for the primary/tracked route which in this case should be the

FastEth0/1 interface on RTR1

*2 Whenever I set this command I get this WARNING: %Warning:Use P2P interface for routemap

set interface clause

It appears to take the command anyway.

If I am understanding how this should work you would need the route-map policy next-hop to be the next hop of your backup route and not the next-hop of the

primary route. In addition I am not sure why you need the set interface null0. It does not appear to be supported in the way I am trying to use.

Any help/clarification here is greatly appreciated.

I have this problem too.
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dwesterhouse Mon, 08/25/2008 - 13:12

Some addtional information when performa a test failure on the RTR1 tracked object

RTR2#sh track

Track 123

Response Time Reporter 1 reachability

Reachability is Down

18 changes, last change 00:13:35

Latest operation return code: Timeout

Tracked by:

STATIC-IP-ROUTING 0

FFSRouter#sh ip route track

ip route x.x.x.x 255.255.255.0 FastEthernet0/1 track 123 state is [down]

ip route x.x.x.x 255.255.255.0 FastEthernet0/1 track 123 state is [down]

ip route x.x.x.x 255.255.255.0 FastEthernet0/1 track 123 state is [down]

FFSRouter#sh ip route

Gateway of last resort is x.x.x.x to network 0.0.0.0

S x.x.x.x/24 is directly connected, Serial0/0/0:1 - This is the correct backup route

S x.x.x.x/24 is directly connected, Serial0/0/0:1 - This is the correct backup route

S x.x.x.x/24 is directly connected, Serial0/0/0:1 - This is the correct backup route

x.x.x.x/16 is variably subnetted, 2 subnets, 2 masks

C x.x.x.x/29 is directly connected, FastEthernet0/1 - Primary

C x.x.x.x/30 is directly connected, Serial0/0/0:1 - Secondary

S* 0.0.0.0/0 [1/0] via x.x.x.x

-------------------------------------------

RTR1#sh track

Track 123

Response Time Reporter 1 reachability

Reachability is Down

18 changes, last change 00:13:35

Latest operation return code: Timeout

Tracked by:

STATIC-IP-ROUTING 0

The routing table also showed the correct entries while the primary link (wireless) was in a fail test (we simply powered down the bridge), but then I could not ping nor get other traffic to flow between the routers.

According to what I am seeing in the sh track, sh ip route track and sh ip route commands both routers should be using the serial0/0/0:1 (T1) line to pass all traffic between the routers and it should work!!! This driving me crazy... Please advise... Am I going crazy? Is there an easier way to do this?

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