Understanding of Bandwitdh term

Unanswered Question
Jun 9th, 2008

Hi Experts,

I am trying to figure out this..

Currently I have a 2M Wan Link and will be upgraded to 4M Metro E soon.

Currently the highest peak traffic reach the highest 2.2m based on my graph..

First question:

IS this possible as my full wan link capacity only 2M and didn;t subcribe to any over-burst traffic Link?

And if i upgrade to 4M, is it means that user access will be faster in term of everyone access at the same time and 4M will have a big pipe for them to access?



I have this problem too.
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n.nandrekar Mon, 06/09/2008 - 01:11

Regarding your first question " IS this possible as my full wan link capacity only 2M and didn;t subcribe to any over-burst traffic Link?

" , it is possible that the traffic peaked to 2.2 just for a small time interval and was actually queued in and sent over the link.

second question "And if i upgrade to 4M, is it means that user access will be faster in term of everyone access at the same time and 4M will have a big pipe for them to access? "

would depend on what kind of traffic and the remote side.

Assuming that there are no drops on the remote side, the increased bandwidth will definitely make the user access faster. But "faster" here is a relative term. Assuming that with 2M connection, traffic was being dropped because it was exceeding the 2M limit, this should solve the problem as now there should be no drops due to bandwidth and this should result in less re-transmissions.



cindylee27 Mon, 06/09/2008 - 01:28

Thanks Niranjan..

Another question..how can i improve on the traffic speed at the router end?

Any commands i can put in to make the routing faster?

n.nandrekar Mon, 06/09/2008 - 01:42

No specific commands. Would depend a lot on which router / modules you are using and the network topology. You could use Qos features if supported to give priority to some specific type of traffic to reduce the latency but thats only in case of congestion.

(Please rate the post if it has helped ).



cindylee27 Mon, 06/09/2008 - 01:49

Thanks once again..last question..

Can I have an example like let's say I want to have lotus notes(1352/tcp) as top priority.?


Joseph W. Doherty Mon, 06/09/2008 - 03:40

From your original post, you didn't note what kind of link was your 2 Mbps WAN link. If it's a serial E1, not quite sure how you saw 2.2 Mbps. If the link is also a MetroE with a handoff of 10 or 100 Ethernet, which is what I assume the 4 Mbps MetroE upgrade would be, then the 2.2 Mbps probably measures a burst which may, or may not, have been dropped by your WAN provider if the rate was considered out of contract. Much depends on how the provider enforces bandwidth.

Whether a 4 Mbps would seem "faster" to your users; much depends on the nature of the traffic that's crossing the link and the applications being used. Bulk transfers, something as simple as opening a large file, like some slideshow file, will probably take less time. Interactive access, which is often dependent on latency, might see almost no improvement unless the link has been heavily congested and the additional bandwidth reduces its queuing latency.

If there's competition between different flows for bandwidth, then a QoS configuration that minimizes bandwidth hogs from impacting interactive flows, could offer even better user perceived performance than a bandwidth upgrade (it also can be used with additional bandwidth for further improvement).

With regard to your question of making Lotus Notes top priority; normally only real time applications are given top priority. "Mission critical" applications are provided sufficient bandwidth to minimize their queuing delay.

Actual examples are very dependent on the platform and often also on the software version running on the platform.

For your 4 Mbps MetroE upgrade, if supported by your platform, I would first recommend shaping at that rate since providers often use a combination of FIFO and policing. Router shapers appear to support WFQ. If the performance of your mission critical application of Lotus Notes isn't acceptable, I would then suggest increasing its IP Precedence up so that the WFQ shaper provides in more bandwidth. If this still is insufficient, then, if supported, you might want to migrate to CBWFQ configuration providing your Lotus Notes traffic a minimum guarantee of bandwidth.

cindylee27 Mon, 06/09/2008 - 06:49

Thanks Joseph..

THe link is Metro Ethernet link..

Good reply..:)

Well, the lotus notes is just an eg: Infact, I would like to provide more for the video content..

Do you have any examples at the cisco that you can point me too?

Thanks again..Appreciate your reply.


Joseph W. Doherty Mon, 06/09/2008 - 16:09

You might start at www.cisco.com/go/qos

Actual implementation very much depends on the capabilities of the platform, especially the switches. For instance, on many software based routers, generic traffic shaping (GTS) could be as simple as:

FastEthernet #

shape 2000

Configuration becomes more complex if you want to emphasis some traffic.


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