Friday, September 28, 2012

VoIP QoS on Cisco 3560 Switches with Polycom and Cisco IP Phones

Today we are going to setup network Quality of Service (QoS) for Voice over IP (VoIP) traffic generated by Polycom and Cisco IP phones. Our goal here is to tag the VoIP packets so that they are placed in a priority outgoing queue so that if the available bandwith is saturated, then the VoIP packets will be the last ones to be dropped by the switch. VoIP is a delay-sensitive application while bulk data transfers are not. When a switch port gets more data that it can handle, the switch will start dropping packets. If a VoIP packet is dropped, people having a conversation will hear a glitch. We don't want that and this is why we must treat the VoIP packets differently than other data packets.

Thursday, September 27, 2012

IOS Upgrade on Cisco WS-C4507R Chassis with Dual Supervisor V Engines

Today we will upgrade the IOS version on both WS-X4516 supervisor engines V in a WS-C4507R chassis. This blog post assumes that your 4507R chassis's supervisor engine already has network support for you to SSH into it.

First, go to the Cisco support site and download the latest IOS version (you need a Cisco support contract to have access to new IOS images). Place this image on your TFTP server. In this example, the TFTP server is a CentOS Linux machine called