QOS on a Cisco LAN inferstructure wtih IPT

[iptuser]

We have chosen our IPT supplier-Cisco 4.0 However though QOS is requred in a WAN is it really needed for LAN? Implementing QOS will add addtional prcoessing time but in a LAN install there should be enough bandwidth. Has anyone any thoughts either way and experience of not using QOS in a LAN and resulted in any problems


thanks

wayne

 

[BuckWeet]

QoS on the LAN isn't as big of deal, providing that you have gigabit backbone and 100Mbps to the desktop. But just make sure you setup a voice vlan to seperate traffice, and then 802.1p should work just fine for you.. When you get into a multisegment layer 3 switched environment, then QoS on the LAN might need to be implemented more because of the size of network.


BuckWeet

 

[ADB100]

I have to disagree with BuckWeet on this (and this is information from our Cisco SE). Even if your uplinks have very small utilisation levels (1%) you WILL experience poor quality speech. If you are using FIFO (default) on your Ethernet uplinks (Gigabit etc) then any voice traffic is not prioritised; its just First-In, First-Out. If there is some bursty data traffic then delays are going to occur in delivering your voice packets and you WILL experience speech quality degrading, these delays are not as critical with User Data. QoS must be implemented to stop this behaviour for Voice Traffic. Cisco Catalyst Switches (well most) can use a Priority Queue on the Egress Interface that is constantly serviced, user data can be placed into different queues that are treated in a weighted-round-robin fashion (dependant on hardware etc).

Andy

 

[Sirrono]

I don't think we are running a Gigabit backbone? I think it is 100Mbps, do we have to upgrade to run IPT?

SirRono

 

[bburton48us]

Hi all:

It really does depend on your switch types. Each switch type has a different ASIC that handles each individual port, and the QoS features are port dependent. If you send me a list of switch types I can forward the basic QoS commands for each type. Please include native versus CatOS operating system, and, port types on each switch.

Thanks,

Bill B.