Re: Networking Question

You need to implement QoS on the router. Create three queues, high, medium
and scavenger. Place your telnet application in the high queue, your VPN
traffic (any traffic that is destined for the corporate office) into the
medium queue, and your internet traffic (everything else) into the scavenger
queue. Telnet is not high bandwidth, so allocate the minimum bandwidth (5%
or 64k or something like that), 65% to the medium, and the rest to scavenger
(or any other numbers that you think are appropriate.) The bandwidth
numbers only count when you have congestion, and even if you have
congestion, any bandwidth that is not used by the queues can be used by the
others if they have exceeded their allocation. If you still have "slowness"
with telnet after implementation, you may have to change the "high" queue to
a priority queue, but I doubt this since you have a T1. With a priority
queue, any traffic in that queue is ALWAYS sent before any other traffic and
the bandwidth you allocate to it will ONLY be used for the priority queue.
So if you allocate 64K, that bandwidth is always reserved even if you don't
have any priority traffic. Priority queues are generally only used for
voice traffic where jitter is problem.


"Trendkill" <jpmason@xxxxxxxxx> wrote in message
news:34b3c69e-1434-40fd-a0b2-22aed2d48cfb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Feb 27, 4:50 pm, sei...@xxxxxxxxx wrote:
Hi,

I have a question on network optimization. I work at a company that
has a corporate office. Our local division has a T1 and VPN through
the AT&T network. We have Cisco routers and switches. The router is
a 2811 and I believe the switches are 2950. Our corporate office is
supposed to handle the major networking issues so I'm limited with
what I can actually do.

We experience two issues. Our main issue is response time from a
telnet application. This application is used by everyone and is
critical to our work environment. Not critical as in "We lose money/
people die every time this thing slows down" but it's a major concern
whenever the thing lags. And it does lag throughout the day.

The server hosting the application is at our corporate office. Our
Exchange server is also at the corporate office.

The telnet app would periodically lag horribly throughout the day.
When it's working well you can type with a barely noticeable delay.
When it's bad, you're typing a bit and then waiting for it to catch
up. We complained but our corporate network guy said we weren't even
using our full T1 line. So, I did a a little investigation during two
verified lag time periods and found that our response times can go
from 40 ms to 450+ ms when things are bad. For example, a user
running a program that needs to grab large bits of information from
the Internet. I guess whatever report they run shows our bandwidth is
fine but telnet is sensitive.

Is there anything we can do? I'd thought we'd be able to set some
policies on the router that would throttle Internet traffic in favor
of telnet traffic but the corporate office (supposedly) tried this and
the users still complained at response times. Well, that and websites
timing out left and right.

Advice, please!

Three things:
A) Make sure your network guy is watching the bandwidth (at a close
interval) via something like mrtg or netflow, and try to figure out if
the response times correspond with high bandwidth utilization. If so,
consider bucketing or throttling your big traffic users (I'd have to
guess email/outlook if your server is remote from your location), but
would also keep an eye out for internet or ftp traffic.
B) Look at QoS to help either prioritize certain traffic (telnet), or
limit the usage of your heavy hitter applications. This can be done
by source, destination, network, port, etc. Your network engineer
should be able to help here.
C) If bandwidth doesn't appear to be the issue, you need to escalate
with your provider. If your latency is going to 400+ms and is not
related to your usage, then there is no excuse from the provider.

One last thing, are you using the VPN over the t1? If so, why? Is
the t1 to the internet (then it would make sense), or is it private?
Either way the VPN should not add too much processing or latency to a
single t1, but something to watch since you only have a 2811. Again,
I don't suspect this, but something to keep in mind.


.

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