[mrtg] Re: Frame Relay monitoring - multiple PVCs

[Rich Adamson]

Howard,

> a question about implementations of  Frame-Relay-DTE mib ( RFC1315 or 
> 2115 ) :
> 
> If there are multiple PVCs on one interface, for sure the router will 
> create an entry in frCircuitTable, I can always use ifIndex and DLCI to 
> identify a PVC. But how about the ifTable ? Does the router create an 
> entry for each of PVC in ifTable as well ?  It looks like cisco will do 
> this , but I'm wondering if any standards talking about this. If device 
> from other vendors deal with multiple PVCs in the same way, I don't need 
> to modify the template.

Cisco and many other vendors are mostly commited to standards where they
exist. Most use RFC1315 for their frame relay implementations, however
Bay Networks (Nortel) invented their own snmp mibs for their frame relay
stuff.

There are no well defined standards for establishing ifTable entries for
each pvc. One can sort of map pvc's into the table through existing
relationships and words, but they are subject to interpretation and 
vendor-dependent implmentations.

It's been a while since I looked at Cisco's ifTable implementation, but if
I recall correctly, Cisco creates an ifTable entry "if" the frame relay
pvc has been defined in the router configuration as a subinterface. If 
subinterfaces are not defined, then I don't believe ifTable entries exist 
for each pvc. (Could be wrong though.)

Not all vendors interpret the RFC's the same either. Cisco participates
heavily in the standards groups and therefore has an advantage from being
involved in the discussion groups leading to an official standard. Another 
company may not have been as actively involved and therefore attempt a
literal translation/interpretation that generally result in variations
in their implementation (including RFC1315).

Cisco is certainly not afraid to add non-standard-based mibs to their 
equipment. Having been around their implementations since the early '80s,
Cisco typically implements "standards" first. If no standards exist and
customer's are vocal, they will implement non-standard mibs. I believe
the ifTable entries for pvc's fall in the later.

Rich


--
Unsubscribe mailto:mrtg-request at list.ee.ethz.ch?subject=unsubscribe
Archive     http://www.ee.ethz.ch/~slist/mrtg
FAQ         http://faq.mrtg.org    Homepage     http://www.mrtg.org
WebAdmin    http://www.ee.ethz.ch/~slist/lsg2.cgi