Wireshark-users: Re: [Wireshark-users] IP Error (Header Checksum) can effect Jitter calculation ?

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From: capricorn 80 <cool_capricorn80@xxxxxxxxxxx>
Date: Tue, 1 Jun 2010 12:31:16 +0000


Thanks Martin. So i should not be worry in case of RTP calculation.

Regards,

Date: Tue, 1 Jun 2010 21:31:40 +1000
From: martinvisser99@xxxxxxxxx
To: wireshark-users@xxxxxxxxxxxxx
Subject: Re: [Wireshark-users] IP Error (Header Checksum) can effect Jitter calculation ?

The most likely cause of checksum "errors" when capturing packets with Wireshark is the driver/NIC combination of the machine you are doing this with. Many NICs are able to offload this function from the main CPU, improving performance. The normal network driver knows to ignore the checksum, not doing the work, and assumes it is being handled correctly by the NIC. Wireshark however calculates the checksum by default and matches it with what is in the packet, reporting the error falsely. It is unlikely you will receive real errors with Wireshark, as the CRC32 checks by the NIC and switch will drop errored packets and you won't see them. So you are best off turning this feature off in the appropriate preferences section for each protocol.

See http://www.wireshark.org/docs/wsug_html_chunked/ChAdvChecksums.html for more details.

Regards, Martin

MartinVisser99@xxxxxxxxx


On Tue, Jun 1, 2010 at 4:55 PM, capricorn 80 <cool_capricorn80@xxxxxxxxxxx> wrote:

Hi!


In IP section


Header checksum: 0x0000 [incorrect, should be 0x5a54]
Bad : True

Regards,





Date: Mon, 31 May 2010 12:27:53 +1000
From: martinvisser99@xxxxxxxxx

To: wireshark-users@xxxxxxxxxxxxx
Subject: Re: [Wireshark-users] IP Error (Header Checksum) can effect Jitter calculation ?


Provided the packet is identified as RTP, it should be included. What errors are you referring to?
On Sun, May 30, 2010 at 2:53 AM, capricorn 80 <cool_capricorn80@xxxxxxxxxxx> wrote:


Hi!

 I have taken few trace of jitter using wireshark. In one of the trace i can see some error in Internet protocl sections. Does that effect the jitter calculation ?

Regards,

Sajid

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