3Com VCX V7122 User Manual page 67

Figure 30 SNMP Managers Table Screen
If you clear a checkbox and click Submit, all settings in the same row revert to
their defaults.
Multiple Routers Support
Multiple routers support is designed to assist the media gateway when it operates in a
multiple routers network. The gateway learns the network topology by responding to ICMP
redirections and caches them as routing rules (with expiration time).
When a set of routers operating within the same subnet serve as gateways to that network
and intercommunicate using a dynamic routing protocol (such as OSPF, etc.), the routers
can determine the shortest path to a certain destination and signal the remote host the
existence of the better route. Using multiple router support the media gateway can utilize
these router messages to change its next hop and establish the best path.
Note: Multiple Routers support is an integral feature that doesn't require configuration.
Simple Network Time Protocol Support
The Simple Network Time Protocol (SNTP) client functionality generates requests and reacts
to the resulting responses using the NTP version 3 protocol definitions (according to RFC
1305). Through these requests and responses, the NTP client is able to synchronize the
system time to a time source within the network, thereby eliminating any potential issues
should the local system clock 'drift' during operation. By synchronizing time to a network time
source, traffic handling, maintenance, and debugging actions become simplified for the
network administrator.
The NTP client follows a simple process in managing system time; the NTP client requests
an NTP update, receives an NTP response, and updates the local system clock based on a
configured NTP server within the network.
The client requests a time update from a specified NTP server at a specified update interval.
In most situations this update interval should be every 24 hours based on when the system
was restarted. The NTP server identity (as an IP address) and the update interval are
configurable parameters that can be specified either in the ini file (NTPServerIP,
NTPUpdateInterval respectively) or via an SNMP MIB object.
When the client receives a response to its request from the identified NTP server it must be
interpreted based on time zone, or location, offset that the system is to a standard point of
reference called the Universal Time Coordinate (UTC). The time offset that the NTP client
3Com VCX V7122 SIP VoIP Gateway User Manual 67