HP 600 Series, Services And Applications

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addresses will not be used. Thus, the subnet mask 255.255.255.252 is the
minimum subnet mask that will provide only two addresses per subnet. Now
that a suitable subnet mask for use on point-to-point links has been deter-
mined, subnet numbers and addresses must be selected.
Table B. Point-to-Point Subnet and Address Definition
16 Bits 8 Bits Upper 6 Bits Lower 2 bits 32 Bits/32 Bits
Network
Number
Subnet
Number
Subnet Extension
Component
Link Address
Component
Full Point-to-Point Link
Addresses
170.200 5 000000 01/10 170.200.5.1/170.200.5.2
170.200 5 000001 01/10 170.200.5.5/170.200.5.6
170.200 5 000010 01/10 170.200.5.9/170.200.5.10
170.200 5 000011 01/10 170.200.5.13/170.200.5.14
The following method of selecting subnet numbers and point-to-point link
addresses illustrates one method of allocating addresses that seemingly
maintains the address structure used in allocating LAN subnets. The first
point-to-point subnet defined in figure 4 was subnet 170.200.5.x, the second
was 170.200.6.x, and so on. To maintain consistency with that addressing
scheme, the point-to-point subnets to be defined will use 170.200.5.x as the
base for selecting link addresses. The last octet (the “x” octet) will be used
to define individual point-to-point subnets and addresses. Table B shows the
allocation of subnets and point-to-point addresses. Extending the subnet
mask to include the upper 6 bits of the last octet for point-to-point links
provides enough address space for 64 point-to-point links.
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Routing with OSPF
Conserving IP Address Space
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