EMM-E6 Ethernet User's Guide

CHAPTER 1: INTRODUCTION
1-30 EMM-E6 User’s Guide
1.10.6 Operation of the Subnet Mask
The Subnet Mask defines how your EMM-E6 treats SNMP Trap IP
destination addresses in its Trap table (see Chapter 7, Trap Table Screen,
for additional information on traps).
When using the Subnet Mask, the EMM-E6 logically determines one of
two possible locations, either on or not on its own subnet, for each Trap
IP destination address in its trap table. If the address is on its own subnet,
the EMM-E6 transmits directly to the workstation with that address. If the
address is not on its subnet, the EMM-E6 transmits to the workstation
with that address combined with the Default Gateway IP address. Default
Gateways are discussed later in this chapter.
Modify the default Subnet Mask for the EMM-E6 when workstations in
the Trap table reside on a different subnet (i.e., across a gateway or
external router), and you want these workstations to receive SNMP Traps
generated by the EMM-E6. Caution should be exercised when
configuring subnets, as a poorly subnetted network can greatly increase
network traffic by duplicating transmissions.
1.10.7 Default Gateway
The Default Gateway is the IP address of the network or host to which all
packets addressed to unknown networks or hosts are sent. The Default
Gateway should be a perimeter or border device that connects the network
with the rest of the world. The Default Gateway attempts to route the
packet to the correct destination. This gateway is often used by managers
to handle all traffic between private networks and the Internet. If a Default
Gateway is not defined, the packets addressed to a network or host
address not found in the forwarding table will be dropped.
CH1Book Page 30 Wednesday, March 20, 1996 7:48 AM