How to switch traffic from one ISP to other ISP automatically.

[nilesh.dubey]

Hi Guys,

I got two routers on different location connected through p2p link. There are two ISP providing P2P connectivity. I am running EIGRP both side over p2p line.

Problem-  When an ISP goes down I need manually shut that ISP port to switch complete traffic on other ISP. Is there a way to do it automatically. Whenever any ISP goes down traffic automatically get switched to other ISP.

Thanks,

Nilesh

[Mark Malone]

You could try use ip sla track an upstream route or interface up/down and when it fails set the next hop ip to be the other router using policy based routing pbr

Your routers will need to be running ipservices for this feature

even though this is nx-os below its the same for ios as an example

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/6_x/nx-os/IPSLA/configuration/guide/b_Cisco_Nexus_7000_Series_NX-OS_IP_SLAs_Configuration_Guide_rel_6-x/b_Cisco_Nexus_7000_Series_NX-OS_IP_SLAs_Configuration_Guide_rel_6-x_chapter_01000.pdf

[nilesh.dubey]

Hi Mark,

I agree with you I think IP SLA can be useful. I going to implement it and I will share the update with you.

Thanks,

Nilesh

[Mark Malone]

I have used in situations like this before to redirect when links go down so it should work ,ye let us know how it goes i can assist if needs be

[nilesh.dubey]

Hi,

I tried to implement below configuration.

R1(config)# ip sla 1
R1(config)# icmp-echo 2.2.2.2 source-interface FastEthernet0/0
R1(config)# timeout 1000
R1(config)# threshold 2
R1(config)# frequency 3
R1(config)# ip sla schedule 1 life forever start-time now
R1(config)# track 1 ip sla 1 reachability

But it seems this router do not accept these command. Please find the router model no and IOS version and suggest if there is some other command.

router - CISCO2901/K9

IOS- Version 15.4(3)M1

Thanks,

Nilesh

[Mark Malone]

Its most likely the license applied to the router than the IOS version , if its just ipbase it wont support ip sla need a higher end licence Security or Data , if that's the case policy based routing wont work either these are advanced features only on the paid licences on routers

Is there dual paths in the eigrp topology tables on these routers for each prefix ? if so you could try influence that way instead

[nilesh.dubey]

There is only single path in eigrp topology. I am coordinating with Cisco license team to get the license.

How did you get to know that its an IP base IOS. Is there any way to recognize that.

Thanks,

Nilesh

[Mark Malone]

Hi

im just guessing from experience its ipbase if the ip sla is not working come across it a few times, most of the advanced features or useful ones Cisco make you pay, so if its not taking its usually the license is the issue  

show license or show license det 

LABRA1#sh license
Index 1 Feature: ipbasek9
        Period left: Life time
        License Type: Permanent
        License State: Active, In Use
        License Count: Non-Counted
        License Priority: Medium
Index 2 Feature: securityk9
        Period left: Life time
        License Type: Permanent
        License State: Active, In Use
        License Count: Non-Counted
        License Priority: Medium

[nilesh.dubey]

can I configure IP SLA  over GRE tunnel ?

Thanks,

Nilesh

[Mark Malone]

Yes once theres reachability through the tunnel to the ip address your trying to ping

[nilesh.dubey]

We have created two tunnel between both location. Both tunnel are on different link. Tunnel do not go down even ISP link is down. I think that's the reason why traffic is not switching automatically. Once we unplug the ISP cable from router, traffic get switched to other link.

I am thinking to enable ip sla service on tunnel interface so that it can track the tunnel connectivity. Will it work on tunnel?

Thanks,

Nilesh

[Mark Malone]

set the ip sla to ping something past the tunnel upstream like loopback on router , so once the ISP link is down even if tunnel stays up if ip sla cant ping the ip it will fail over anyway doesn't matter tunnel stays up as long as ip becomes unreachable as that's what you will track for failover not the tunnel

[nilesh.dubey]

I have configured IP SLA on router but it seems not working properly. ROuter interface is down but IP SLA does not track and switch traffic on other link.

I do not know if Cisco 1941 support IP SLA tracking feature not as there was no option to configure it. I have installed an additional license to configure IP SLA.

Thanks,

Nilesh

[Mark Malone]

can you pst the relevant ip sla config in place and the show ip sla statis

Are you not tracking an upstream route to avoid the issue with the tunnel interface not dropping ?

[nilesh.dubey]

Please find the IP SLA config. Tunnel interface status is down but IP SLA statis is ok and traffic is not moving on other link.

# IP sla 1
# icmp-echo 172.17.1.2 source-interface tunnel 1
# time out 2000
# treshhold 250
# frequency 3
# ip sla schedule 1 life forever start-time now

# track 1 ip sla 1 reachability