Re: [nv-l] Collecting ifInOctets ifOutOctets

[John M Gatrell <John.Gatrell@uk.ibm.com>]

Can't help you directly as I don't have a suitable
compressed link.
Let's assume you mean a Cisco on a Frame-relay link.
If using ip header compression I would get the info
from
'sh frame-relay ip tcp header-compression'

If using stacker or predictor, I would use 'sh compress'
and look up on the Cisco website how to interpret
the results.

Once I had the numbers I would do a unix 'snmpwalk'
command of the entire
mibs on the Cisco box to see if I could find similar
numbers.
For example there is a mib counter
transmission.frame-relay.frCircuitTable.frCircuitEntry.frCircuitSentOctets.9.36
where the 36 on the end is probably a frame-relay
dlci number.
This might or might not be the compressed value.

If this is too much work, then just do the 'show compress'
once by hand,
work out the compression ratio and assume it's not
going to change.

To tell if the link is overloaded is easier. The BECNs
counter will be non-zero.
transmission.frame-relay.frCircuitTable.frCircuitEntry.frCircuitReceivedBECNs.9.36

Use Header compression if there are smallish data
packets.
Use Stacker on file transfers which aren't already
compressed on small Cisco's with good cpus.
Use Predictor on file transfers which aren't already
compressed on Cisco's with lots of memory.

> Thank you John,
> your answer lead me to a second question:
> Is there a way to measure the compressed traffic? 
> (that is the true traffic on the link?)

> TIA

> Costas


--- John M Gatrell <John.Gatrell@uk.ibm.com> wrote:

> From my memory, if it's a Cisco, the counters are
> before compression,
> and so will give you higher than expected
> throughputs.
> 
> The Cisco 'show compress' command gives you more
> info,
> but you then have to add various columns to work out
> the true link 
> utilization.
> 
> If the compression is done externally in modem
> hardware then again the 
> figures
> muust be for the uncompressed traffic.
> 
> John Gatrell, BA, AIX Cert Specialist, Cisco CCNA.
> 
> >When we collect the ifInOctets & ifOutOctets of an
> >interface which is the one end of a serial link and
> 
> >we have compression on that link, do we collect the
> >compressed or the uncompressed octets???