Cisco WS-X4604-GWY - VoIP Gateway Especificaciones descargar pdf (Pagina 59)

2-25

Cisco IP Telephony Network Design Guide

78-11103-03

Chapter 2 Campus Infrastructure Considerations

IP Addressing and Management

Connecting to the Network

The following steps outline the process that takes place when an IP phone is

powered up and plugged into the network:

1. The IP phone begins a CDP exchange with the switch. The phone issues a

trigger CDP to force a response from the switch. That response contains the

VVID for the phone.

2. If the IP phone is configured to use DHCP (the default), it issues a DHCP

request on the voice subnet it got from the switch. This is the recommended

mode of operation. Static addressing can be used, but it prevents mobility.

3. The IP phone gets a response from the DHCP server in the network. Along

with the DHCP response, which provides the IP address to the telephone, it

is also possible to supply the address of the TFTP server from which the

phone gets its configuration. This is done by configuring option 150 on the

DHCP server and specifying the address of the TFTP server; Cisco DHCP

server supports this feature. Again, it is possible to specify the TFTP server

address manually, but this would limit adds, moves, and changes, as well as

remove some other benefits.

4. The IP phone contacts the TFTP server and receives a list of addresses of

Cisco CallManagers. Up to three Cisco CallManagers can be specified in the

list. This provides redundancy in case the first Cisco CallManager in the list

is not available.

5. The IP phone now contacts the Cisco CallManager and registers itself,

receiving in return a configuration file and runtime code necessary for the

phone to operate. For each configuration, the IP phone receives a directory

number (DN) from the Cisco CallManager to be used for calling that

particular IP phone.

6. The IP phone is ready to make and receive calls.

Note This process takes about 90 seconds. To speed it up, turn on portfast

and turn off port channeling and trunking. This reduces the time to

about 30 seconds.

1 2 ... 54 55 56 57 58 59 60 61 62 63 64 ... 261 262

Sin comentarios

Cisco WS-X4604-GWY - VoIP Gateway Especificaciones Pagina 59