IP SLA HELP

[soumik.mondal]

Dear All

We have two internet connections for our DC .

45 MBPS-  GigabitEthernet0/2 ---------------- ISP -A   IP ADDRESS 100.236.65.253

2 MBPS-GigabitEthernet0/3----------------------ISP-B   IP ADDRESS  202.138.226.253

DNS- of ISP-A   100.236.167.130

We use static route with 10 AD to ISP -B

ip route 0.0.0.0 0.0.0.0 100.236.65.254
ip route 0.0.0.0 0.0.0.0 202.138.226.253 10

So when ISP-A goes down traffic routed to ISP-B and reverts back when ISP-A is up.Now the problem is sometimes ISP-A is not physically down , but internet connectivity is not there .We are unable to ping the DNS of ISP-A 100.236.167.130.In that scenario we have to remove the route for ISP A for make ISP-B working.

To solve the problem I have tried with IP SLA .

R1(config)# ip sla 1
R1(config)# icmp-echo 100.236.167.130
R1(config)# timeout 500
R1(config)# threshold 2
R1(config)# frequency 5
R1(config)# ip sla schedule 1 life forever start-time now

R1(config)# track 1 ip sla 1 reachability

R1(config)#ip route 0.0.0.0 0.0.0.0 100.236.65.254 track 1

Now when primary link goes down, traffic routed through ISP -B.But when it is up, traffic is not routed through ISP-A.I have checked that during this time ip route 0.0.0.0. 0.0.0.0 100.236.65.254 is not showing in routing table and track 1 is showing down.I have have to add route 0.0.0.0.0.0.0. 100.236.65.254 then track 1 becomes up and all traffic is routed through ISP-A.

But if I give 100.236.65.254 as track IP everything is working fine.

Please help meregarding this.

Thanks & regards

Soumik Mondal

Message was edited by: Soumik Mondal

[Thotsaphon Lueangwattanaphong]

Hi,

   You need to tell the router how to reach the DNS of ISP-A. Just add the following command for testing.

Router(conf)#ip route 100.236.167.130 255.255.255.255 100.236.65.254

     Please let us know how things work out.

HTH,

Toshi

[soumik.mondal]

Thanks for your reply.

I can not test till the week end .

[Antonio Knox]

Sounds to me like the reason for this is because once the second route takes over, there is nothing telling the router to failback to the original route because per your ip sla config, it sees 100.236.167.130 as reachable, so your configuration takes no action. 

Does this make sense?

[Antonio Knox]

Add this

track 1 ip sla 1 reachability

default-state up

delay down 60 up 60

Should help you out a bit.

[soumik.mondal]

Dear all

The problem solved after I add the route

Router(conf)#ip route 100.236.167.130 255.255.255.255 100.236.65.254

But This is not working

Track 1 ip sla 1 reachability

default-state up

delay down 60 up 60

Thanks & Regards

Soumik

[soumik.mondal]

Dear all .

The previous problem of fail -over is sorted out.Thanks to all for the responces .Now I have another requirement .My management wants the aggregation of the ISP A and ISP B.If I go for multilink, I want to know that the perfomance or flapping of one link will effect the another.If there is any solution .My router is 7206 , IOS is 12.4(24) T4...

[Antonio Knox]

Please create a new thread for your new query so that all members of the community that can help with the requirement will be better able to identify and respond to the query on the Discussions Board.