Providing Network Professionals The Edge

Archives for January 2012

Cisco Gatekeeper Bandwidth Allocation

A Cisco Gatekeeper has a pre-defined bandwidth number which it allocates per call (based on the CODEC being used). These values are not typically … [Read more...]

SIP Response Codes

SIP Response codes are a means of communication for the Session Initiation Protocol.  They are pre-defined responses to SIP Requests which have been … [Read more...]

Cisco IP Phone SCCP (Skinny) Call States

Cisco IP Phone SCCP (Skinny) Call States This is a list of SCCP call states sent by CUCM to SCCP endpoints: 1—Off Hook 2—On Hook 3—Ring … [Read more...]

SRST: Maximum IP Phones and Line DNs Supported Per Platform

SRST (Survivable Remote Site Telephony) provides a mechanism for remote site IP phones to continue to operate in case of WAN failure.  IP phones … [Read more...]

What is GARP (Gratuitous ARP Protection)?

Gratuitous ARP (protection) This is an example of a typical standards based (beneficial) LAN feature which can be used in some cases by the bad … [Read more...]

Configuring Voice VLANs (Catalyst 3750 and 3560)

In many cases clients would like to have their employee's PC connected directly to the 3-port switch on the back of the Cisco IP phone sitting on the … [Read more...]

Cisco Inline Power PoE Commands

Cisco (PoE) switches by default have their PoE (Power over Ethernet) enabled on every port.  This article shares some of the common CLI commands to … [Read more...]

Cisco IP Phone Boot Process

Clearly understanding the Cisco IP phone boot process is a very important part of the troubleshooting process for any Cisco network engineer.  I will … [Read more...]