[mrtg] Re: Traffic info of real interface and virtual interface

[Kruepke]

Based on my understanding of IRB, the behavior you are seeing does make sense.

When using IRB, some traffic can be routed, while other traffic can be bridged AND routed.  For example, you can put an interface in a bridge-group, and you can assign it an IP address.  Let's say you have two Ethernet interfaces, which each are a separate IP network, but they share an Appletalk cable range.  But you also need to route the Appletalk traffic out a serial interface to get to other cable ranges.  Then you could route IP at the interfaces and bridge Appletalk.  To route the bridged Appletalk traffic, you would use the BVI.

Well, this may or may not have been new information for you, but now that we are on the same page (hopefully)...

In the example I mentioned above, the IP traffic is routed at the interface.  Therefore, it would  never hit the BVI.  This would be one source of discrepancy.  Of course, if you are not routing anything at the physical interface, then this does not apply.

Now for some speculation.  If you get Appletalk traffic that needs bridging, does it hit the BVI?  I do not know.  It is possible that traffic that does not need to be routed could never make it into the stats for the BVI.

Sorry--this e-mail may have not answered your questions as much as just restated them as new questions.  But I personally would not be surprised by the different values of the counters, even though I am as curious as you to know the REAL reason.  If anyone else has any ideas, I would love to hear them.

Keith

----- Original Message ----- 
From: "Takeo Shibata" <takeo at visualhawaii.com>
To: <mrtg at list.ee.ethz.ch>
Sent: Wednesday, July 12, 2000 3:48 PM
Subject: [mrtg] Traffic info of real interface and virtual interface



I start measuring the traffic using MRTG, but it shows the different
result between the real interface and virtual interface.

I use CISCO-1605R(It has 2 ethernet interfaces(Ethernet0, Ethernet1) 
and one serial interface(Serial0)

Ethernet1 is only interface in Bridge-group 3.
But the amount of traffic between Ethernet1 and
BVI3 is different.

Serial0.1(Sub interface of serial0) is only interface in Bridge-group 2.
But the amount of traffic between Serial0.1 and
BVI2 is different.
Is this resonable?.
Why ?

I have ADSL user and each has one DLCI number.
One ADSL cliant has only one distinctive serial sub interface(Serial0.#)
In this case, which value(BVI2 or Serial0.1) should be used for
ADSL cliant usage?

Thank you.

Tak


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