Understanding VT errors on SONET

[jrsaw2731072]

Many times we are looking for errors on our SONET network which has MSPP and ODXC nodes and we come across ES-V or SES-V on the 15310-CL / MA nodes. Im told this means there are errors somewhere on the path on the virtual layer. It takes some looking but we find the errors on a random node.

I kinda get the virtual layer but not really, can you explain it to me?

and

Is there a better way to search for the virtual errors other than opening each node to look at the performance tab?

-Jim

[ksj · Accepted solution]

You have line, section and path in a SONET network. Section is between regenerators and/or network elements, line is between neighboring network elements, and path is a virtual layer on top of that. It allows you to create an end-to-end connection between and through network elements where there may be repeaters and/or more than two network elements. Simple network without being in a ring:

physical      : start<-ne<--->regen<--->ne<--->ne->end

virtual path  : start<-ne<-------------------->ne->end

Any physical network link, element or regenerator that the path rides over can have the Errored Seconds (ES) or Severely Errored Seconds (SES) which will be reported up the stack to the virtual path(s) that ride over those physical links.

Note that all three layers appear between network elements as well as regenerators. The path layer is the one that lets you extend a circuit beyond a point to point between two network elements.

HTH

[jrsaw2731072]

KSJ,

  That makes sense, thank you for drawing it out.

Is there a way to find out which node along the VT has the error? I usually find the VT errors at the end nodes and have to search each node to find the actual errors.

-Jim

[ksj]

We usually monitor the stats for all devices with SNMP & have traps for excessive levels of these types of errors. If it is a carrier circuit it is a lot more difficult as you need to convince them it isn't your equipment causing the errors. That's pretty easy by showing an outgoing stats on one end and incoming on the other (at the SONET layers).

I will say that while it is easy to prove, it can be pretty hard to convince carriers even when you show them that proof.

[jrsaw2731072]

I agree 100%. I feel most of my phone calls are trying to convince an vendor or local carrier the errors are coming from them. Thank you KSL

-Jim