IP SLA on Reuter

[saquib.tandel]

Hi Experts

Here is my config for IP SLA, how to track reachability over routing protocol.

Primary link is Point to Point

Backup link via MPLS cloud - Service Provider network

attached is network layout

IOS Version on Branch 12.4

Configuring IP SLA on branch router

ip sla 1

icmp-echo 10.150.10.254 source-interface GigabitEthernet0/0

timeout 1000

threshold 2

frequency 3

ip sla schedule 1 life forever start-time now

thanks

Saquib

[Richard Burts]

Saquib

What you have posted shows how you will initiate IP SLA and it looks reasonable. But you have not shown us how you will use IP SLA or where and how it is assigned. Without that we can not see how it would work.

HTH

Rick

[saquib.tandel]

Hello Richard

how to configure IP SLA in a routing protocol scenario - that was my question

I understand with static routes it would look like

track 1 rtr 1 reachability

ip route 0.0.0.0 0.0.0.0 x.x.x.x track 1

ip route 0.0.0.0 0.0.0.0  Y.Y.Y.Y 140

Point 2  -  Our NMS checks for interfaces up/down but in MPLS cloud scenario it can be interface issue or issue at SP side no reachability. Our idea was to see if IP SLA can support to track interface up/down and reachability

Hope i am clear

thanks

Saquib

[Neeraj Arora]

Saquib,

IP SLA route tracking feature is an alternate solution for Routing protocols. When you cannot use a dynamic routing protocol, that where you'd use IP SLA for tracking a static route so that when the remote ip stops pinging, the primay route would automatically failover to the backup.

But in your case, I don't understand why do you want to use IP SLA for a routing protocol? You have OSPF on your primay link and running BGP on the secondary, so if your primary link goes down (even if the interface stays up but the connectivity to other remote router is not there) routing protocol will automatically detect this failure as it would not be able to send or receive Hello packets and bring the OSPF neighborship down and BGP backup route would be installed to start sending the traffic over MPLS.

Really as per me you don't need IP SLA tracking and fyi there is no way to track an IP SLA object anything in a routing protocol config

Hope it helps

Neeraj

[saquib.tandel]

Thanks Neeraj on your feedback

Other options to overcome Point 2 concern

Point 2  -  Our NMS checks for interfaces up/down but in MPLS cloud  scenario it can be interface issue or issue at SP side no reachability.

thanks

saquib

[Neeraj Arora]

even for this 2nd point of tracking the interface through NMS, your end goal should be to make sure that Branch office is reachable from HQ at all times.

So even if your NMS software at HQ is not able to reach the MPLS facing interface on the Branch router, regardless of the fact whether it is an interface related issue or SP infra issue, you would get to know that reachability through MPLS is down and you have to take action. You can start by checking the interface on the router, then MPLS cable and then contact SP so that they can check at their end

But if you WANT that instead of NMS alerts, you want that router should generate an alert, only then you would use IP SLA with EEM feature.

[Vasileios Bouloukos MSc, ITIL, CCIE · Accepted solution]

Hi Saquib,

Regarding the point 2 you can Configure a Tracked List and Boolean Expression in order the IP SLA can support

to track interface up/down AND reachability as you requested.

A tracked list contains one or more objects. The Boolean expression enables two types of calculation by using either "and" or "or" operators.

For example, when tracking two interfaces using the "and" operator, up means that both interfaces are up,

and down means that either interface is down.

You can find detailed examples to the next link:

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t15/feature/guide/fthsrptk.html

hope that helps!

Vasilis