Heart beat over P2P circuit

[spmccoy]

Here's the situation.  We currently have two sites that are connected via a point to point circuit.  This is the primary circuit for network traffic betwee the two sites.  As a back-up, both sites are also connected through an MPLS cloud.  At both sites, the p2p circuit is an ethernet hand-off from the telco that connects to a Catalyst 4500X.  The problem we are running into is we have no visibilty past the telco's on premise equipment.  If the p2p circuit goes down somewhere past the on premise equipment, our monitoring software will still see the switch ports that it connects to as being up.

My question is this.  Is there a way to setup a heart beat between two Catalyst 4500X switches that are connected by a point to point circuit?  The ports are layer three and have IP addresses assigned to them.

[Flavio Miranda · Accepted solution]

Hello,

Had you considered IP SLA ?

SW(config)# ip sla 1
SW(config-ip-sla)# icmp-echo X.X.X.X source-interface Fa 0/0
SW(config-ip-sla)# timeout 2000
SW(config-ip-sla)# threshold 2000
SW(config-ip-sla)# frequency 3
SW(config-ip-sla)# exit
SW(config)# ip sla schedule 1 life forever start-time now
SW(config)# track 1 ip sla 1 reachability

Then you can even play with route in case you want to change your traffic flow to a backup link.

SW(config)# ip route 0.0.0.0 0.0.0.0 10.1.1.2 track 1
SW(config)# ip route 0.0.0.0 0.0.0.0 10.2.2.2 20

[spmccoy]

That looks like the best option.  I'll give it a try.  Thanks.

[Flavio Miranda]

Good Luck and thanks for rating!!

[Julio E. Moisa]

Hi 

Additional to Flavio's comment, you should consider the following timers for IP SLA:

Consider the following guidelines before configuring the frequency (IP SLA), timeout (IP SLA), and threshold (IP SLA) commands. For the IP SLAs UDP jitter operation, the following guidelines are recommended:

• (frequencyseconds ) > ((timeoutmilliseconds ) + N)

• (timeoutmilliseconds ) > (thresholdmilliseconds )

where N = (num-packetsnumber-of-packets ) * (intervalinterpacket-interval ). If you are running Cisco IOS IP SLAs Engine 3.0, use the num-packets command and the interval (params) commands to configure the values that define N. Otherwise, use the udp-jitter command to configure the num-packetsnumber-of-packets and intervalinterpacket-intervalvalues.

Reference: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/command/sla-cr-book/sla_s2.html#wp4194409343

:-)