3com 812 Manual De Usuario
DHCP
6-27
caller identity (and finds, then connects to, the recipient’s IP address). The IP
address of the intended recipient is their (SIP) phone number.
address of the intended recipient is their (SIP) phone number.
By creating and storing a caller identity, a proxy server enables party A to call
party B (and vice-versa), even if the recipient’s IP address (SIP phone number) is
not specifically known to the caller. Additionally, through the implementation
of a user name and password scheme, the proxy server provides a simple yet
effective security mechanism for SIP phone callers and call recipients alike.
party B (and vice-versa), even if the recipient’s IP address (SIP phone number) is
not specifically known to the caller. Additionally, through the implementation
of a user name and password scheme, the proxy server provides a simple yet
effective security mechanism for SIP phone callers and call recipients alike.
When a SIP phone user places a call to a conventional telephone connected to
the PSTN (Public Switched Telephone Network), the call is passed to the
conventional telephone via a voice gateway.
the PSTN (Public Switched Telephone Network), the call is passed to the
conventional telephone via a voice gateway.
Voice Gateway
As the last major link in the SIP phone network infrastructure, the voice
gateway forwards the IP address (SIP phone number) received from the proxy
server to the telephone company’s Central Office (CO). Once received by the
CO, the IP address is mapped to a conventional (non-SIP) phone number. From
this point on, the phone call is processed through the telephone company
network like any other non-SIP phone call originating from a conventional
telephone.
gateway forwards the IP address (SIP phone number) received from the proxy
server to the telephone company’s Central Office (CO). Once received by the
CO, the IP address is mapped to a conventional (non-SIP) phone number. From
this point on, the phone call is processed through the telephone company
network like any other non-SIP phone call originating from a conventional
telephone.
For more information about 3Com SIP phone products, please see our web site at
http://www.3com.com/products/sip
.
DHCP
Dynamic Host Configuration Protocol (DHCP) is designed to provide a centralized
approach for configuration of IP addresses and parameters.
approach for configuration of IP addresses and parameters.
When a workstation is configured for automatic assignment of IP addresses, it
broadcasts a request out on the LAN. The DHCP Server responds with an IP
address for the workstation, the domain name, and the IP addresses of the default
router, two DNS Servers, and two WINS Servers.
broadcasts a request out on the LAN. The DHCP Server responds with an IP
address for the workstation, the domain name, and the IP addresses of the default
router, two DNS Servers, and two WINS Servers.
The assignment of an IP address to the workstation is for a specified period of
time, referred to as the lease period. Before the lease is set to expire, the
workstation will send a request to the server to extend the lease period. The server
maintains a list of assigned IP addresses and the duration period of the leases.
When a lease expires, the IP address can be reassigned to another workstation.
time, referred to as the lease period. Before the lease is set to expire, the
workstation will send a request to the server to extend the lease period. The server
maintains a list of assigned IP addresses and the duration period of the leases.
When a lease expires, the IP address can be reassigned to another workstation.
The OCR 812 can be configured to support up to 40 workstations on the local
LAN. In addition, the OCR 812 can be configured to be a DHCP Relay. When
enabled, the Relay will process the broadcast request from the local workstation
and send it to one or two remote DHCP servers. The response from the remote
DHCP servers is processed and forwarded to the local workstation.
LAN. In addition, the OCR 812 can be configured to be a DHCP Relay. When
enabled, the Relay will process the broadcast request from the local workstation
and send it to one or two remote DHCP servers. The response from the remote
DHCP servers is processed and forwarded to the local workstation.
Remember to save your configuration using the save all command before
rebooting your OCR 812 so that your changes will be written to permanent FLASH
memory.
rebooting your OCR 812 so that your changes will be written to permanent FLASH
memory.
Configuring the DHCP
Mode
The OCR 812 has three DHCP modes: Server, Relay and Disable.
To configure the mode, use the following command:
set dhcp mode [SERVER | RELAY | DISABLE]