REIJS@SURFNET.NL (10/22/90)
> > As a result of the Sydney WG2 meeting, the proposed amendment to ISO > 8348/Add2 to remove the preferred decimal encoding will be sent out for > ballot as ISO 8348/PDAM 4. > > This admendment does not preclude the use of the decimal encoding, it > simply removes its specification (and the corresponding requirement > that all NSAPs can be encoded using it) from the scope of the > Addressing Addendum. This requirement was the limiting factor in > the restrictions placed upon the length of DSPs with binary > abstract syntax. (You can look at the scheme for decimal encoding of > DSPs with binary abstract syntax [8.3.2.d] and verify that the values given > in table 3 represent the largest (measured in octets) binary value that > can be encoded into a 40 decimal digit NSAP after encoding the IDP). Is the decimal encoding still valid (it is only not PREFFERRED)? I thought that at this moment e.g. X.25 does use decimal encoding. Correct? So in case there is a possibility that different encoded subnetworks are connected, then the gateways/interworking units must be able to translate from binary to decimal encodings. In that case it must be possible to translate a binary encoded address into a decimal encoded address en vice versa. How is it then possible to change the length of the binary abstract syntax? If it is 20 octets long, it does not fit in the decimal encoding! Can somebody explain this to me? All the best, _ _ _ _ |S| |U| |R| |F| ___________________________|___|___|___|_________________________ | | | (n) (e) (t) Victor Reijs tel: +31 30 310290 Network development fax: +31 30 340903 SURFnet b.v. E-mail: Reijs@SURFnet.nl P.O.box 19035 Memocom: (124)27:sir003 3501 DA Utrecht The Netherlands
dougm@WARTHOG.NCSL.NIST.GOV (Doug Montgomery) (10/24/90)
>From: REIJS%SURFNET.NL@cunyvm.cuny.edu >Subject: binary abstract NSAP address length >To: iso@nic.ddn.mil > >Is the decimal encoding still valid (it is only not PREFFERRED)? I thought >that at this moment e.g. X.25 does use decimal encoding. Correct? > >So in case there is a possibility that different encoded subnetworks are >connected, then the gateways/interworking units must be able to translate >from binary to decimal encodings. In that case it must be possible to >translate a binary encoded address into a decimal encoded address en vice >versa. How is it then possible to change the length of the binary abstract >syntax? If it is 20 octets long, it does not fit in the decimal encoding! > >Can somebody explain this to me? YES, the decimal encoding is still valid. What is important here is how Network protocols convey OSI NSAPs. Protocols standards dictate how OSI Network Addresses are encoded and coveyed in PDUs (so called Network Protocol Address Information). It is my understanding that current use of X.25 to support the CONS conveys OSI NSAPs using the preferred binary encoding. In situations where it is required to interwork with protocols and subnetworks that employ decimal encoding of *full OSI NSAPs* to do addressing, then one may need to be careful about the length of NSAPs with binary abstract syntax DSPs. dougm