tcpdump mailing list archives

Re: Inefficiency in BPF code for DLT_RAW


From: Darren Reed <Darren.Reed () Sun COM>
Date: Wed, 23 Dec 2009 20:35:13 -0800

On 23/12/09 06:09 PM, Guy Harris wrote:
On Dec 23, 2009, at 2:01 AM, Darren Reed wrote:

The links that support the IP tunnels are a fixed type, be
it IPv4 or IPv6, and are reported as being DLT_RAW because
there is no real layer 2 header present.

        ...

In the face of modern processors, this might seem like
micro-optimisation but I see it more as a precision error:
it is not possible to precisely tell libpcap (and thus the
BPF compiler) that a link only sees one protocol and
therefore does not need to handle both protocol cases.

Thoughts?

DLT_IPv4 and DLT_IPv6?

Works for me.

Darren

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