Re: traffic shaping for C2620 on IOS12.5


Igor Mamuzic wrote:
You shouldn't use priority command because it could lead to starvation of
other traffic... This is suitable only for delay non-tolerant apps such as
VoIP. You should use bandwidth percent command, but keep in mind that if
prioritized traffic rate exceeds bandwidth percent rate this traffic becomes
best effort if not otherwise specified, so it's suitable only for small bw
traffic such as RDP and telnet, but it works relatively ok for http traffic
in my case. So, if you want to absolutely ensure that smtp traffic doesn't
eat all bw you have even if your prioritized classes exceeded their reserved
bw then you must shape smtp traffic:
instead of bandwidth percent, just type shape average under policy-map
config mode. Of course, if there is a little amount of traffic other then
SMTP this could be a wasting of bw since SMTP is no longer able to posses
the whole bw even if there is no other traffic currently flowing trough the
link.

B.R.
Igor


"Ronnie Corny" <ronniecorny@xxxxxxxxxxx> wrote in message
news:ectm4f$bjh$1@xxxxxxxxxxxxxxxxxxxxxxx
hi James

thanks for the tips... this really helps a lot...

you're right, i mistyped my IOS version... it's 12.3(5b)... haven't taken
time to upgrade the IOS yet as i have to schedule the few minutes of
downtime...

Hi,

Warning - wandering a bit OT.

You can definately reduce the impact of this
with QoS however you may also wish to consider
looking at the source of the problem.

Maybe you are getting the following:-

I have seen Exchange fill up networks before.

This can happen if you are sending big e-mails to a
lot of different addresses e.g. a mail-shot with an attached
document.

The problem is that (Exchange 2000 numbers) by default
MS in their wisdom have allowed exchange to
have 10,000 sessions open simultaneously. When
something like a mailshot arrives it tries to send
too much at once.

Exchange system Manager/Administrative Groups/
First Administrative Group/Servers/your-server/
Protocols/SMTP/whatever-it-is/Right-click

Properties/Delivery/Outbound Connections

Limit number of connections 5 (was 10,000)
" " per domain 2 (was bigger)

I just fancy these numbers as opposed to fewer since it
protects you from a conection getting hung up stalling the
mail queue forever.

By all means try a few more.

To exacerbate the problem observations that I have made
suggest to me that the Windows 2000 Server (and others)
TCP stack was broken which meant that the link was
in fact incorrectly oversubscribed and even the mail did
not get through.

Finally, if you are sending single e-mails to multiple
addresses you can defer the break-out of these e-mails
into individual mesasges. Typically the e-mail client sends
a single message to the local e-mail server. It then
breaks out the messages and sends the individual messages
out. Alterntively - if you configure your server to relay messages
via your ISP (say) you can defer this break-out process
to the ISP's mail server. Under the circumstances described
this can reduce your link traffic.

BTW - (Exchange 2000 again) Configuring a smart host
on the "server" will not accomplish the deferal. You need to
do it with a routing group.

YMMV with other exchange versions.

.

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