Справочник Пользователя для Cabletron Systems EMM-E6 Ethernet

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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