Specifications

Setting Up the Network
How to Set Up the Network
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Cisco IOS Survivable Remote Site Telephony Version 3.4 System Administrator Guide
DETAILED STEPS
Defining the DHCP Relay Server
This task sets up DHCP relay on the LAN interface where the Cisco IP phones are connected and enables
the Cisco IOS DHCP server feature to relay requests from DHCP clients (phones) to a DHCP server. For
further details about DHCP configuration, see the Cisco IOS DHCP Server document.
The Cisco IOS DHCP server feature is enabled on routers by default. If the DHCP server is not enabled
on your Cisco SRST router, use the following steps to enable it.
SUMMARY STEPS
1. service dhcp
2. interface type number
3. ip helper-address ip-address
4. exit
Command or Action Purpose
Step 1
ip dhcp pool pool-name
Example:
Router(config)# ip dhcp pool pool2
Creates a name for the DHCP server address pool
and enters DHCP pool configuration mode.
Step 2
host ip-address subnet-mask
Example:
Router(config-dhcp)# host 10.0.0.0 255.255.0.0
Specifies the IP address that you want the phone to
use.
Step 3
option 150 ip ip-address
Example:
Router(config-dhcp)# option 150 ip 10.0.22.1
Specifies the TFTP server address from which the
Cisco IP phone downloads the image
configuration file. This needs to be the IP address
of CallManager.
Step 4
default-router ip-address
Example:
Router(config-dhcp)# default-router 10.0.0.1
Specifies the router to which the Cisco IP phones
are connected directly.
• This router should be the Cisco SRST router
because this is the default address that is used
to obtain SRST service in the event of a WAN
outage. As long as the Cisco IP phones have a
connection to the Cisco SRST router, the
phones are able to get the required network
details.
Step 5
exit
Example:
Router(config-dhcp)# exit
Exits DHCP pool configuration mode.