HP 600 Series, Services And Applications

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Dividing a DECnet internetwork into areas provides two advantages. First, it
takes advantage of the entire range of network addresses available to you.
Second, it improves the efficiency of your internetwork by reducing the
volume of control messages. Each router maintains a database of all nodes
that are in its area. This information is periodically exchanged with other
routers in the area. The only information that is maintained about other
areas is the route to take to reach those areas. Dividing the internetwork
into areas reduces the amount of information that routers have to maintain
and exchange with one another.
Planning for a DECnet internetwork involves defining areas and assigning
unique addresses to each router and end node in the internetwork. When
configuring DECnet nodes, individual addresses must be configured on each
router and end node. Note that a single address is assigned to the router
itself, not to each port or interface on the router.
DECnet addresses consist of:
a 6-bit area number (1–63)
a 10-bit node number (1–1023)
The area number and the node number are separated by a period. For
example, the DECnet address 1.10 specifies node 10 in area 1.
A DECnet internetwork is shown is figure 1. It consists of two areas
connected through an X.25 network.
Figure 1. DECnet Internetwork
* marks the designated router
for the LAN adjacent to the *.
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DECnet Routing Service
General Addressing Considerations
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