High-Speed Interface Counters

High-Speed Interface Counters

Post by Bill Lundgre » Tue, 06 May 2003 23:54:13



Quick Question.

When dealing with high speed (Gig and higher) interfaces, does anyone know
what OID MRTG uses for it's interface stats?

We came across a bug in our in-house monitoring system, in that we were
always polling the standard in/out octet counters.  However, these aren't
absolute values, and get recycled after a billion octets or so.  On a gig
link that's busy, that doesn't take long.

So, we found that interface absolute values are contained in
'1.3.6.1.2.1.31.1.1.1.6', which is ifHCInOctets and
'1.3.6.1.2.1.31.1.1.1.10', ifHCIOutOctets.  These are all SNMP Version 2c
OID's.

So, is MRTG smart enough to poll the right one on gig interfaces?
Otherwise, as we found, if you poll the V1 OID's, your graphs will be
sckewed, and tend to now show the right information.

 
 
 

High-Speed Interface Counters

Post by Daniel J McDona » Wed, 07 May 2003 01:55:57



>Quick Question.

>When dealing with high speed (Gig and higher) interfaces, does anyone know
>what OID MRTG uses for it's interface stats?

Depends on what you tell it.

Quote:

>We came across a bug in our in-house monitoring system, in that we were
>always polling the standard in/out octet counters.  However, these aren't
>absolute values, and get recycled after a billion octets or so.  On a gig
>link that's busy, that doesn't take long.

>So, we found that interface absolute values are contained in
>'1.3.6.1.2.1.31.1.1.1.6', which is ifHCInOctets and
>'1.3.6.1.2.1.31.1.1.1.10', ifHCIOutOctets.  These are all SNMP Version 2c
>OID's.

>So, is MRTG smart enough to poll the right one on gig interfaces?

If you run a recent version of cfgmaker and you specify snmp version 2c,
then yes.  For information on specifying snmp version, see the manual
concerning targets.

Quote:>Otherwise, as we found, if you poll the V1 OID's, your graphs will be
>sckewed, and tend to now show the right information.

although there are strategies for dealing with that, such as cutting down
the polling time to 1 minute (but letting mrtg still summarize it at 5
minute intervals.)

 >

--
Daniel J McDonald CCIE # 2495, CNX
Visit my website: http://www.austinnetworkdesign.com

 
 
 

High-Speed Interface Counters

Post by Bill Lundgre » Wed, 07 May 2003 02:44:00


Thanks!




> >Quick Question.

> >When dealing with high speed (Gig and higher) interfaces, does anyone
know
> >what OID MRTG uses for it's interface stats?

> Depends on what you tell it.

> >We came across a bug in our in-house monitoring system, in that we were
> >always polling the standard in/out octet counters.  However, these aren't
> >absolute values, and get recycled after a billion octets or so.  On a gig
> >link that's busy, that doesn't take long.

> >So, we found that interface absolute values are contained in
> >'1.3.6.1.2.1.31.1.1.1.6', which is ifHCInOctets and
> >'1.3.6.1.2.1.31.1.1.1.10', ifHCIOutOctets.  These are all SNMP Version 2c
> >OID's.

> >So, is MRTG smart enough to poll the right one on gig interfaces?
> If you run a recent version of cfgmaker and you specify snmp version 2c,
> then yes.  For information on specifying snmp version, see the manual
> concerning targets.

> >Otherwise, as we found, if you poll the V1 OID's, your graphs will be
> >sckewed, and tend to now show the right information.

> although there are strategies for dealing with that, such as cutting down
> the polling time to 1 minute (but letting mrtg still summarize it at 5
> minute intervals.)

> --
> Daniel J McDonald CCIE # 2495, CNX
> Visit my website: http://www.austinnetworkdesign.com

 
 
 

1. How to solve MIB counters wrapping problem on high speed ATM interfaces?

I am working a product that does SNMP polling and analyzing on Cisco
Routers.

One big problem I have in supporting Hight speed ATM (OC3, 12, 48)
interfaces is that the 32 bit SNMP1 MIB counts like

ifInOctets
ifOutOctets
ifInUcastPkts
ifInNUcastPkts
ifOutUcastPkts
ifOutNUcastPkts

wrap too fast ( in approximately 5 minutes on a 100 Mbps interface).

I heard that SNMP II has 64 bit counters but how many Cisco routers
support SNMP II ?

I can not make the polling too often (less than 2 minutes), so while
it's possible to support OC 3 (155 Mbps) ATM interface, it's still
not sufficient for OC 12 (622 Mbps) or OC 48 (2.4G bps).

Does anybody know any solutions to this problem?
How does Cisco's management software resolve this problem themselves?

Thanks in advance.

Leo

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