What are the Best Practices for Using DHCP for Acquiring IP Addresses in Cisco Business Edition 3000 system

This document does not provide detailed information on DHCP; you should have a thorough understanding of DHCP before you use it with your Cisco Business Edition 3000 system. Typically, the IT support staff for the company or the Internet service provider handles your DHCP setup. DHCP may be run on a computer or on a router. Before you implement DHCP with Cisco Business Edition 3000, consider the following best practices:

• Use custom option 150 or option 66.
  
• You can use a DHCP server to issue IP addresses to the phones.

If DHCP is enabled on a phone, which is the default for the phone, DHCP automatically assigns an IP address to the phone after you connect it to the network. The DHCP server directs the phone to the Cisco Business Edition 3000 server, which serves a phone-specific configuration file to the phone.

If DHCP is not enabled on a phone, you must manually assign an IP address to the phone and configure the IP address or the hostname of the Cisco Business Edition 3000 server locally on the phone (configure it under the TFTP server option on the phone).

• The Cisco Business Edition 3000 server must use a static IP address that you assign to it. If you use a DHCP server to issue IP addresses to computers and other network devices, make sure that the IP address for the Cisco Business Edition 3000 server is not in the active range of IP addresses on the DHCP server. Make sure that you configure your DHCP server so that it does not hand out the IP address for the Cisco Business Edition 3000 server to a different network device.
  
• Cisco strongly recommends that you assign a static IP address to the gateway. If you use a DHCP server to issue IP addresses to computers and other network devices, make sure that the IP address for the gateway is not in the active range of IP addresses on the DHCP server. Make sure that you configure your DHCP server so that it does not hand out the IP address for the gateway to a different network device.
  
• If DHCP is enabled on a gateway, DHCP automatically assigns an IP address to the gateway after you connect it to the network.
  
• Before you configure your sites and DHCP, Cisco strongly recommends that you determine the number of sites that you need and determine how many phones will be located at each site. Configure your DHCP server so that it correctly distributes the IP addresses to the phones at the various sites.
  

IP Addressing

The Cisco MCS7890-C1 uses two external IP addresses. The main IP address is the published IP address on the MCS7890-C1 device. This is the system IP address of the Cisco Business Edition 3000. This IP address is set by your administrator during the First Time Setup of Cisco Business Edition 3000. You can configure this IP address using DHCP or static. The second IP address is the IP address of the media resource used for transcoding and conferencing. Cisco recommends that the media resource IP address be static and unique for MCS7890-C1.

Note For Cisco ISR2901 gateway, themedia resource IP address is the same as the ISR2901 gateway IP address.