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Compression to increase wan performance

 
 
Igor Pinchevskiy
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      08-09-2007
Hello,

I'm doing research if compression trough a router would improve
performance on T1 point to point wan links. We are using 2600 series
routers, any info, advice, or articles would be greatly appreciated!

Thank you in advance,
Igor Pinchevskiy

 
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Peter
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      08-10-2007
Hi Igor,

> I'm doing research if compression trough a router would improve
> performance on T1 point to point wan links. We are using 2600 series
> routers, any info, advice, or articles would be greatly appreciated!


Unfortunately this type of question fits into one of those "it
depends" type scenarios.....;-( The areas you need to consider if
compression would help are -

- Can the other end of your WAN link also handle
compression/de-compression (both ends need to do it).
- The platform performance (is it currently lightly/heavily loaded).
A 2600 would not have a lot of CPU spare if handling a T1 with a
moderate amount of ACL's being processed. If the link is already
queing a moderate amount of traffic then I would not consider it
without some form of offload for compression, but then consider the
cost of this.
- Also take into account the type of traffic you are passing on the
link. EG VPN traffic is encrypted and would not compress well (if at
all), however plain text or HTML with buckets of embeded white space
could provide great returns. Also consider that it takes time to
comress/uncompress so there is an overhead for doing this.

Overall we abandoned using compression on our WAN around 2000, it was
no longer viable, but then your situation could still benefit from
it..

Cheers.....................pk.


--
Peter from Auckland.
 
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Bod43@hotmail.co.uk
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      08-10-2007
On 10 Aug, 01:42, "Peter" <(E-Mail Removed)> wrote:
> Hi Igor,
>
> > I'm doing research if compression trough a router would improve
> > performance on T1 point to point wan links. We are using 2600 series
> > routers, any info, advice, or articles would be greatly appreciated!

>
> Unfortunately this type of question fits into one of those "it
> depends" type scenarios.....;-( The areas you need to consider if
> compression would help are -
>
> - Can the other end of your WAN link also handle
> compression/de-compression (both ends need to do it).
> - The platform performance (is it currently lightly/heavily loaded).
> A 2600 would not have a lot of CPU spare if handling a T1 with a
> moderate amount of ACL's being processed. If the link is already
> queing a moderate amount of traffic then I would not consider it
> without some form of offload for compression, but then consider the
> cost of this.
> - Also take into account the type of traffic you are passing on the
> link. EG VPN traffic is encrypted and would not compress well (if at
> all), however plain text or HTML with buckets of embeded white space
> could provide great returns. Also consider that it takes time to
> comress/uncompress so there is an overhead for doing this.
>
> Overall we abandoned using compression on our WAN around 2000, it was
> no longer viable, but then your situation could still benefit from
> it..


The absolute best thing to do is to try it.
Monitor CPU usage in the routers while testing.

I agree with all of Peter's points above.

One thing that is a pretty certain winner if you are using TCP
is van Jacobsen TCP Header compression. You
may need to turn on PPP but it looks like you will still
be ahead.

Consider also the network end to end latency
which may be causing your orformance problems.

If you add more detail someone may be able to
comment further.

 
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Scott Perry
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      08-10-2007
Yes, data compression will increase data throughput. Products available to
compress data and then decompress data on both sides of the connection are
the Cisco WAAS, Riverbed Steelhead, and Packeteer WAN accelerators. Some of
the products brag a 90% compression on TCP connections with UDP being passed
through uncompressed. Some of the products encapsulate all compressed data
into a single tunneled connection between the end accelerator devices while
others simply compress the payload and decompress the payload on the other
side.

--

===========
Scott Perry
===========
Indianapolis, Indiana
________________________________________
"Igor Pinchevskiy" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) s.com...
> Hello,
>
> I'm doing research if compression trough a router would improve
> performance on T1 point to point wan links. We are using 2600 series
> routers, any info, advice, or articles would be greatly appreciated!
>
> Thank you in advance,
> Igor Pinchevskiy
>



 
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stephen
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      08-10-2007
"Igor Pinchevskiy" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) s.com...
> Hello,
>
> I'm doing research if compression trough a router would improve
> performance on T1 point to point wan links. We are using 2600 series
> routers, any info, advice, or articles would be greatly appreciated!


the other posters suggested / implied using s/w compression, but i would be
wary of using it on a line at this speed.

the compression AIM (2600 XM only AFAIR) can do hardware compression and
should be happy at T1 speeds.

even if the data isnt compressible (and some nearly always is), the headers
will be.

typical office traffic often compresses around 2:1, but badly written apps
can show much higher gains as their packets are full of empty padding.

with a hardware compressor on a serial link, you normally find that delay
for compressed packets goes down - the reduction in bits needed and
associated delay offsets the time taken for compress / decompress.

1 thing to watch is that compression needs a reasonably clean line - if
circuit bit errors are causing 1% or so corrupted frames, then compression
will resend packets, and that can destroy the gain.
>
> Thank you in advance,
> Igor Pinchevskiy
>

--
Regards

http://www.velocityreviews.com/forums/(E-Mail Removed) - replace xyz with ntl


 
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Igor Pinchevskiy
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      08-13-2007
Thank you for all your input, it looks like I need to do a lot more
reading on this subject.

 
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