From: James.Jackson@broadwing.com
Date: Fri Jul 04 2003 - 14:04:10 GMT-3
Agreed, if stress testing you'll want to use 64 byte packets in order to
maximize pps before you hit bandwidth limitations. Similarly it's fair to
say that figures you see stated for pps were achieved with small packets but
this does not imply a direct correlation between packet size and pps
performance. If on the other hand you're trying to simulate typical internet
traffic you can use the rough 7:4:1 distribution for 64 byte, 512 byte, 1500
byte respectively.
Cheers,
James
-----Original Message-----
From: wing_lam@jossynergy.com [mailto:wing_lam@jossynergy.com]
Sent: Friday, July 04, 2003 11:23 AM
To: Ivan Centeno
Cc: ccielab@groupstudy.com; Colin Barber; Jackson, James (DS
Engineering)
Subject: RE: switch router performance
Hi Ivan,
Very clear explanation and thank you so much.
Thx all,
BBD (Big Black Dog)
Ivan Centeno
<icenteno2001@yah To:
wing_lam@jossynergy.com, Colin Barber <Colin.Barber@telewest.co.uk>
oo.com> cc:
ccielab@groupstudy.com, "'James.Jackson@broadwing.com'"
07/04/2003 11:51 Subject: RE: switch router
performance
PM
Wing,
The issue between packet per second and packet size is
about two different performance measures:
1) Switching capacity and
2) Bandwidth or Backplane or interface capacity.
IF you have a non-modular router with ONLY two T1
Interfaces (it is a hypothetical example) you are only
able to switch 1.54 Mbps between the two interfaces.
Maybe you have a Backplane of 100Mbps and this means
you are non-blocking in the Backplane.
1.54 Mbps means a maximum of 3000 64 bytes packet per
sec (approx) if your packet size is of 128 bytes that
means 1500 packet per second.
If the router switching capacity is just 2000 packet
per second (just a education example) you could have
loss packet if the packet size is 64 byte but you are
ok with the 128 byte packet size.
The reasons to choose the 64 byte packet size to
measure performance is to be sure to be process the
packets as fast as they arrive to the interface. This
performance SHOULD be the same with 128 bytes packets
but in the real world it will depend of the memory bus
of the routers amongst other factors.
Best Regards
Ivan Centeno
CCIE #10746.
Packet Networks Manager.
--- wing_lam@jossynergy.com wrote:
> Thanks Barber, and all responders,
>
> Now I really got confused, I found several replies
> and some tell dependent
> (2) while some tell independent (2).
>
> Does it means that if the product spec doesn't
> mentiuons, we should always
> assuming 64 byte packets?
>
> Is it true that the pps is inverse portional to the
> packet size? (Say 20k
> pps @ 64byte will means 853 pps @ 1500 byte packet)
> Or it's non-linear and
> the product doc. should menions about it? (say 20k
> pps @ 64 byte, but 15k
> pps @ 1500 byte)
>
> How about the switches? Does all the above applies?
> Does fps mentioning
> 1500 byte frames?
>
> Thanks a lot for your kindness,
> BBD (Big Black Dog)
>
>
>
>
>
>
>
>
> "Colin Barber"
>
>
> <Colin.Barber@tele To:
> "'James.Jackson@broadwing.com'"
> <James.Jackson@broadwing.com>,
> west.co.uk>
> wing_lam@jossynergy.com, ccielab@groupstudy.com
>
> cc:
>
>
> 07/04/2003 04:03
> Subject: RE: switch router performance
>
> PM
>
>
>
>
>
>
>
>
>
>
>
>
> It is not independent. If it doesn't state you
> should assume 64 Byte
> packets.
>
> -----Original Message-----
> From: James.Jackson@broadwing.com
> [mailto:James.Jackson@broadwing.com]
> Sent: 04 July 2003 06:54
> To: wing_lam@jossynergy.com; ccielab@groupstudy.com
> Subject: RE: switch router performance
>
>
> 20k pps or 20k fps should be independent of packet
> size.
>
> James
>
> -----Original Message-----
> From: wing_lam@jossynergy.com
> [mailto:wing_lam@jossynergy.com]
> Sent: Thursday, July 03, 2003 9:08 PM
> To: ccielab@groupstudy.com
> Subject: switch router performance
>
>
> Hi group,
>
> If a router is labelled 20k pps, does it mentioning
> 64 Byte packets or 1500
> Byte packets? Will this pps reduces if packet size
> becomes larger?
>
> Also, if a switch mentioning 20k fps. does it
> reference to any length of
> frame? Will this fps reduces if frame size becomes
> larger?
>
> Thx,
> BBD (Big Black Dog)
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