EMM-E6 Ethernet User's Guide

REVIEW OF ADDRESSING

EMM-E6 User’s Guide 1-31

1.10.8 Addressing Example

A network manager, planning for the conﬁguration of a network of 60

hosts, desires to implement subnets to create logical divisions between

different groups of workstations and devices. The Internet Assigned

Numbers Authority has supplied the company with a Class C Network

Address; 222. 131. 99. XXX.

Examining Table 1-6 for subnet masking forms, the Network Manager

decides that, due to the extent of subnetting to be implemented, the last

option in the subnet table is not realistic, as that conﬁguration offers only

two subnets. Likewise, the ﬁrst three options are unacceptable, as they

would create an excessively large number of subnets with relatively few

individual hosts per subnetwork. This leaves decimal masks of 248 (31

subnets, 6 hosts each), 240 (15 subnets, 14 hosts each), and 224 (6

subnets, 30 hosts each). Any of these decimal masks would support the

number of Host IDs to be conﬁgured. Looking ahead, the Network

Manager realizes that adding Host IDs to a full network can involve a

total reconﬁguration of subnet strategies, and opts for the decimal mask

240, which provides room for the conﬁguration of 210 Host IDs.

After taking time to fully plan and delineate the required subnets, assign

them to departments within the company, plan out the initial Host IDs for

existing devices within those subnets and conﬁgure the router(s) which

will interconnect the various subnets, the Network Manager determines

where on the network the network management station will reside. The IP

Host ID of this network management station will be essential when

conﬁguring the network devices for sending SNMP Traps.

On any subnet, one Host ID must be reserved for a connection to the

router(s) which will interconnect multiple subnets.

NOTE

CH1Book Page 31 Wednesday, March 20, 1996 7:48 AM