MavEtJu's Distorted View of the World - 2005-02

Posted on 2005-02-21 13:02:07, modified on 2006-01-09 16:29:23
Tags: Voice over IP, Cisco, tftp, DHCP

For a new project within BarNet, we're going to use the Cisco solution for Voice-over-IP. The central server will be the Cisco Call Manager (and friends), the phones will be Cisco 7970 phones.

DHCP-wise these devices aren't too demanding, it asks for the TFTP server and something like option 150 (which is unspecified as far as I can tell). The TFTP server option is a string with the hostname or IP address of the TFTP server. The option 150 is, after going through the documentation of the Cisco gear, *also* for specifying the TFTP server, but then only with the IP address.

So the DHCP configuration should be (for people using the ISC DHCP server):

option cisco-tftp code 150 = array of ip-address;
class "cisco7970" {
   match if substring (option vendor-class-identifier,0,37) = "Cisco Systems, Inc. IP Phone CP-7970G";
   option arp-cache-timeout 60;
   option cisco-tftp 192.168.1.1,192.168.1.2;
   option tftp-server-name "cisco-cm.mavetju.org";
}

Update

There is a draft for the option 150 available at: http://www.ietf.org/internet-drafts/draft-raj-dhc-tftp-addr-option-00.txt