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Re: TO COMPRESS OR NOT TO CMPRS (please reply)
Dave,
At 09:00 AM 2/18/97 -0800, carrel@ipsec.org wrote:
>> I agree. Compression is beneficial. At the very least it is able to
>> compensate for IPSEC overhead which is nice in both end systems and
>> intermediate
>> systems.
>
>Er, no. "At the very least" compression provides no benefit in packet size
>and increases computational load. (I'm not sure if I'm correcting your
>colloquial english or your understanding of compression.) There is no
>guaranteed compression. In the case of interactive traffic like telnet,
>compression will have very little benefit. In the case of ftp data traffic
>(large MTU sized packets), compression _may_ save you from having to
>fragment when encrypting. But only if the data is not already compressed.
>In the case of ftp, data IS quite often already compressed.
I should not use colloquial English!
You are correct. Actually, compression can cause expansion which would
be "the very least". When IP all traffic traffic is considered compression
can have some benefits assuming that compression can negate IPSEC overhead
on larger packets. Small packets do not compress well. There is no advantage
to compressing a packet which does not compress well. My point was that
if you find one that does, there may be some advantage to sending it
compressed.
>
>Now don't get me wrong. I'd like to see the ability to support
>compression. (Life is more than telnet and ftp.) But don't assume its a
>panacea.
I agree.
Derek
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