Title: Message
John,
> I'm going to merge files from
captures on multiple interfaces.
>
Unfortunately I have some duplicates appearing in the traces I am
merging.
> Has anyone seen any utility to
do duplicate packet removal ?
I have tinkered with this sort of problem when
comparing two traces of the same task taken from client and
server. I was more interested in what sort of packets were
being delayed in
transmission. My naive solution
would be to:
- mung
the output of both files using tethereal -x and generate a single line of text
per frame
-
fudge the timestamps of one of the trace files so that traces are aligned
properly
- sort and pipe the output through
uniq
-
un-mung back into a suitable format for text2pcap to read.
But
that isn't going to work in general
- How do you ensure that the real world clocks are
synced for two traces?
- How much of fudge factor is needed to comparing the timestamps of
frames in the two traces?
- If
trace 1 sees 2 pings to an IP address and trace 2 sees 3. How do you decide
whether there were 3, 4 or 5 (or 8!) pings
really?
- What if trace 1 says packet A arrived before B
and trace 2 says B arrived before A?
It may be easier to advise you if we understood what
sort of packets were being duplicated? Eg is it MAC level broadcasts, RIP
updates etc, HSRP hellos?
Alistair
Registered Office:
Marks & Spencer p.l.c
Michael House, Baker Street,
London, W1U 8EP
Registered No. 214436 in England and Wales.
Telephone (020) 7935 4422
Facsimile (020) 7487 2670
www.marksandspencer.com
Please note that electronic mail may be monitored.
This e-mail is confidential. If you received it by mistake, please let us know and then delete it from your system; you should not copy, disclose, or distribute its contents to anyone nor act in reliance on this e-mail, as this is prohibited and may be unlawful.
The registered office of Marks and Spencer Financial Services PLC, Marks and Spencer Unit Trust Management Limited, Marks and Spencer Life Assurance Limited and Marks and Spencer Savings and Investments Limited is Kings Meadow, Chester, CH99 9FB.
