Track Link Status

Unanswered Question
Aug 8th, 2010
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Hi Guys

I have two links from Sales office to distributor office, Link1 is metro link 30mb, Link2 is mpls from service provider.

Link2 is only needed when Link1 is down. Worse happens when Link1 is down and we notice link2 down as well.

How do I track Link2 Mpls working when Link1 is up and running.

I'm quite new in setting up this. I would appreciate if anybody could  post a sample configuration similar to my needs?

    Sales Office


  |            |

Metro    MPLS

   |            |

   |            |

   |            |

   | ospf     |

   \cost5  /ospf cost 25

    \        /






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gatlin007 Sun, 08/08/2010 - 12:08
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Chances are you exchange routes with your MPLS service provider with a dynamic routing protocol such as BGP or OSPF.  When the MPLS circuit loses integrity the routing protocol session/adjacency will get interrupted and produce a syslog trap as a result. 

Sending syslog traps to a network management server that can in turn send an email alert or update a dashboard will keep you informed as to the status of routing over the link. 

Of course having your management server simply ping the service provider side of the MPLS circuit may be easier.  Also keep an eye out for syslog traps based on link status; although with some media the customer side link rarely goes down and the problem is in the cloud.  Keying in on the health of the dynamic routing protocol is helpful when the outage is in the cloud between you and your service provider.

If you don't have an management server get one Install a free UNIX/LINUX distro on modest hardware and you'll outdo commercial software in a couple weeks.


anthony.dyne Sun, 08/08/2010 - 12:28
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Hi Chris

Thanks for replying the post. You made it look so simple.

The key point on MPLS link "What if something wrong in the MPLS Cloud" not on my router interface or next hop.

How can that be tracked by management software

If I put the same question to myself ??? 

I get an answer

Step 1  : " Track a host on distributor end using MPLS connection"

Step  2 : " Track a host on distributor end using metro network"

Will a management software track based on link or I need to configure IP SLA with conditions.



gatlin007 Sun, 08/08/2010 - 12:41
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Nagios works good for this.

Nagios can send email alerts based on syslog traps.  These traps will occur if the dynamic routing protocol session/adjacency is lost due to the MPLS link losing integrity.   In my opinion having awareness of the health of the routing protocols is the best way to deal with this particular issue.

I'll guess you have a /30 network with your service provider over the MPLS circuit?  Ping the SP side of the /30 to determine if the circuit has integrity.

Using ping from a management server in a fault tolerant network can me misleading sometimes; consider the case where a ping could still hit the service provider target of a surviving link; even though the service provider circuit is down.

You could use IP SLA on the router; but you'd still need to get the trap out to a management server to generate an alert or update a dashboard.


anthony.dyne Sun, 08/08/2010 - 13:01
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Thanks again Chris

Can you help with IP SLA config

I posted dummy config without bgp of SP

Interface fa 0/0/1

description "MPLS"

ip address

Interface fa 1/0/1

description "Metro Network"

ip address

Interface fa 0/0/0

description "LAN"

ip address

router ospf  2

network area 0

network area 0


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