Installing and Administering OSI Transport Services

Chapter 1 65
HP OTS/9000 Resources
General Recommendations for NSAP Addresses
General Recommendations for NSAP
Addresses
Here is a list of recommendations by HP for the allocation of NSAPs for
use with OTS:
• Use an Administrative Prefix obtained from a national or
international authority if at all possible. An authority does not have
to reside in the same country as the petitioning organization (for
example, a company in Spain could petition AFNOR for an
Organization Identifier).
• If the Local Format is to be used, the network must be completely
isolated from public network traffic. If a customer needs a temporary
AP, they should use a International Telephone Number, or the X.121
format.
• Use the binary AFI value whenever possible.
• If using a temporary AP, limit the length of the PAP to 14 octets or
less. This will allow the PAP to fit into the space allowed by a national
or international authority’s AP in the future.
• If using an AP allocated by an international or national authority,
define all 20 octets of the NSAP, even if this means allocating a
reserved field.
• Define and manage the PAP address structure independent of the AP.
This will make managing multiple AP values, or migrating between
AP values easier. This especially includes the following fields:
Area ID Routing Domain ID Subnet ID
All the above fields should be unique regardless of AP value, even if
the authorities administering the APs have defined the full DSP. For
instance, if a network administrator is managing a MAP network and
a U.S. GOSIP network, the values used in the Subnet ID fields for the
MAP network NSAP addresses should not be reused in the Area ID
values in the U.S. GOSIP NSAP addresses.
• All fields should be defined to fall on octet boundaries, that is, they
should always contain an even number of hexadecimal digits.
• To be compatible with the ISO IS-IS Routing Protocol, the last three
fields of the PAP should conform to the 2/6/1 format.