Subject: [ippm] test packet size over IP network

From: raymond zhang <[email-masked]>
Date: Thu, 25 Jul 2002 08:55:47 -0700

Hello all,

I wonder if anyone can provide some references or input in selecting test 
packet size for measuring one-way-delay.

RFC 2679 or RFC 2330 does not provide any sort of recommendation.  Does 
that mean it is left up to the SPs ? The problem with this leaving upto the 
service providers is when we need to integrate SLA path should different 
SPs choose different test packet sizes.

Any input would appreciated.

Regards,
Raymond

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From: Matthew J Zekauskas <[email-masked]>
Date: Thu, 25 Jul 2002 12:35:05 -0400

> packet size for measuring one-way-delay.

draft-ietf-ippm-owmetric-as-00.txt is a (very) initial attempt to try to
address this, among other issues.

As always, "it depends on what you are trying to measure".

I can tell you what the two systems I know well do.  The Surveyor system
used minimal-sized UDP packets, which in our case was 12 bytes (so the
physical packet size adds the UDP, IP, and any MAC header).  The RIPE-TT
system used 100 byte UDP packets the last time I looked.

The idea behind small packets was to not send significant traffic, and just
get a broad overview of the network's health.

I'd be interested in what other vendors use and why (I know there are
a few on the list).

--Matt

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From: Venkat Kankipati <[email-masked]>
Date: Thu, 25 Jul 2002 11:00:00 -0700

>I'd be interested in what other vendors use and why (I know there are

We, at Cisco, have a performance monitoring feature in IOS (currently being used by 
a large customer base) which consists of probes which can measure performance for 
various domains (web server, voip networks, etc). Depending on the probe type, our 
measurement packet size varies but we do provide the option for users to configure the 
packet sizes (payload).

Thanks,
Venkat

>--Matt

Venkat Kankipati
Manager, Software Development
IOS Engineering (IOS Technology Division)
Cisco Systems, Inc.
[email-masked] / 408.527.9269

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From: raymond zhang <[email-masked]>
Date: Thu, 25 Jul 2002 10:54:23 -0700

>get a broad overview of the network's health.

If this is the goal, then the smaller test probe packets seems to be a 
better choice without putting whole of traffic over the network.   Private 
IP networks seem to have bigger average packet sizes than ones in the 
public internet so 64 byte packet may be too small so 100 byte (including 
payload, udp and ip) seems to be the balance.

>'

I'd also be interested in what other SPs use as well...