Delay between networks

mcelec · ‎03-25-2008

Hi folks,

My network is growing on, then, I made some diferent new networks, (192.168.0.0 LAN1-Current), (192.168.1.0 LAN2), etc, I want to manage these networks with a 1750 Cisco Router Fastethernet interface, but I notice I have a delay between LAN1 and LAN2 around 45ms (ping), and the aplication bad performace is noticeble.

Questions are:

Is that delay normal?

Do I need to make any configuration on router?

if that delay is normal, I would prefer exchange my network to Class B whit 23 bits mask.

Can somebody help please???

Martin

Joseph W. Doherty · ‎03-25-2008

The problem you might be seeing is the 1750 doesn't really provide LAN bandwidth level routing performance, especially at 100 Mbps.

pnicolette · ‎03-25-2008

How many devices do you have on each separate network?

If you want one large "flat" network, consider configuring broadcast storm control on all your switch ports.

To route between separate networks, a Layer 3 switch (such as Cisco 3550 or newer) will give MUCH less delay than a 1750.

If you want to make sure the 1750 is doing the best it can, see whether methods like Cisco Express Forwarding (CEF) are being used for most packets. show interface statistics can get you started.

mcelec · ‎03-26-2008

Hi pnicolette,

That configuration is in order to implement VLANs later,then, if I implement VLANs and I do not echange the router, will I get the same delay? or this router making trunking has a better performance?

Thanx for your comment

Martin

pnicolette · ‎03-27-2008

You can expect similar performance. My understanding is that routing between physical interfaces and between virtual interfaces (such as trunked VLANs) occurs similarly.

However, combining the traffic from multiple subnets/VLANs into one physical interface may increase congestion and delay, compared to a setup with three or more physical interfaces with traffic flowing among them all.

Note that the same router when it can CEF-switch most packets may handle ten times more traffic than when it has to process-switch most packets. Use show interface stats to get a rough idea of how your 1750 is operating.

Paul

mcelec · ‎03-27-2008

Thax a lot for your comments Paul,

you need to know that my diferent networks are connected to the same interface of 1750 router with secondary ip, in fact, it is the defaul gateway for all my networks.

192.168.0.0 /24 200 devices

192.168.1.0 /24 50 devices

192.168.2.0 /24 50 devices

thanx again, any comment will be useful

Martin