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Suggestions for Installation and Configuration
Issue 4 August 2006 43
switch can instruct such a 4600 Series IP Telephone to initiate a ping or a traceroute to a
specified IP address. The telephone carries out that instruction and sends a message to the
switch indicating the results. See your DEFINITY
®
or MultiVantage™ Administration
documentation for more details.
As of Release 1.8, if applicable, 4600 Series IP Telephones test whether the network Ethernet
switch port supports IEEE 802.1D/q tagged frames by ARPing the router with a tagged frame.
See VLAN Considerations
on page 91. If your LAN environment includes Virtual LANs (VLANs),
your router must respond to ARPs for VLAN tagging to work properly.
IP Address Lists and Station Number Portability
Release 1.5 of the 4600 Series IP Telephones provided the capability to specify IP address lists
in either dotted decimal or DNS format. Release 1.5 allowed key network elements to have
multiple IP addresses, rather than being restricted to just one address for each element. You
can specify up to 127 total characters in each list of the following devices:
● router/gateways,
● DHCP/TFTP/HTTP servers, and
● the media server.
Upon startup or a reboot, the 4600 Telephone attempts to establish communication with these
various network elements in turn. The telephone starts with the first address on the respective
list. If the communication is denied or times out, the telephone proceeds to the next address on
the appropriate list and tries that one. The telephone does not report failure unless all the
addresses on a given list fail.
Obviously, this capability significantly improves the reliability of IP telephony. Multiple IP
addresses maximize the telephone’s likelihood to communicate with backup equipment if the
primary equipment is not operating or is not accessible. For example, alternate communication
would be needed during a limited network outage.
However, this capability also has the advantage of making station number portability easier.
Assume a situation where the company has multiple locations in London and New York, all
sharing a corporate IP network. Users want to take their telephones from their offices in London
and bring them to New York. When users start up their telephones in the new location, the local
DHCP server will generally route them to the local call server. In this case the call server for
H.323 is the Avaya Media Server and the call server for SIP is the Registration Server. But the
local call server denies service because it knows nothing about these new users. With proper
administration of the local DHCP server, the telephone knows to try a second call server IP
address, this one in London. The user can then be automatically registered with the London call
server.
Chapter 4:
Server Administration contains details on administration of DHCP servers for lists of
alternate media servers, router/gateways, and TFTP servers. For specific information, see DNS
Addressing on page 110.