questions about static routes

[Ge Qu]

Hi,

My boss want to do static route for our MPLS but we have 2 exits for the MPLS feed.

He wants the redundancy of these 2 exits. How i can do static routes to point to the 2 exit and make them redundant?

Thank you. 

[cofee]

You do something like this:

ip route 1.1.1.0 255.255.255.0 10.10.10.10

ip route 1.1.1.0 255.255.255.0 20.20.20.20

If you are just looking for redundancy then you can raise the administrative distance of one of the static routes to value more than 1 then it will only be installed in the RIB when you lose primary static route.

below is the example for floating static route:

ip route 1.1.1.0 255.255.255.0 20.20.20.20 2

[Julio E. Moisa]

Hi

Using floating static routes as Coffee mentioned previously. Lowest administrative distance is preferred.

http://www.ciscopress.com/articles/article.asp?p=2180209&seqNum=7

[Ge Qu]

Hey cofee,

Thank you for your reply.

My questions is, when I have 2 static routes with 2 different distance. When the one with lower distance cannot reach the nexthop, the 2nd static will install to the route table. However, if somewhere alone MPLS is not reachable, static route cannot realize it right? As the nexthop still available , the traffice still going via the 1st route but the actual mpls link is not working in the middle, is there a way to avoid it?

Thank you.

[cofee · Accepted solution]

You can implement IP SLA which can be used to ping a device on the other end, for example if this circuit provides internet connectivity then may be you can ping google server and if destination host is not reachable then remove the static route from RIB.

Yes, your thinking is correct. As long as next hop is reachable static route with default AD of 1 will remain in the RIB and floating static won't be installed.

[Ge Qu]

Perfect. This is exactly what I want. Thank you so much.

Do you have a good IP SLA documentations to suggest?

Thank you.

[Julio E. Moisa]

Hi

Now if you are going to use IP SLA, you could use track and EEM script as well for automatic failover. 

You should use icmp echo , it is an example:

https://supportforums.cisco.com/discussion/11587371/eem-script-alert-ip-sla-failures

other useful link:

https://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-embedded-event-manager-eem/113696-eem-tshoot-igp-00.html

The EEM script will be triggered once an event is detected. 

Also you can take in consideration Jon's suggestion, using dynamic protocols. 

:-)

[Jon Marshall]

You can use static routes as suggested but this is why people use dynamic routing protocols. 

Perhaps explain this to your boss. 

Jon