RFC 1553 (rfc1553) - Page 3 of 23
Compressing IPX Headers Over WAN Media (CIPX)
Alternative Format: Original Text Document
RFC 1553 CIPX December 1993
header into a one to eight octet header.
Lastly, it is possible and many times desirable, to use this type
of header compression in conjunction with some type of data
compression.
Data compression technology takes many forms. Link bit stream
compression is a common approach over very low speed asynchronous
links, normally performed by modems transparently. Transparent bit
stream compression is also offered in some DSUs, routers and
bridges. Data compression can be provided using protocols such as
CCITT V.42bis[3], MNP 5, Lempel-Ziv, or LAPB[4].
When using both header and data compression, the sequence of
compression is important. When sending packets, data compression
MUST be done after header compression. Conversely when receiving
packets, data decompression MUST be done before header
decompression.
IPX Compression Algorithm
The normal IPX header consists of the following fields: checksum,
packet length, transport control (hop count), packet type,
destination and source address fields.
+-----------------------+
| Checksum |
+-----------------------+
| Packet Length |
+-----------+-----------+
| Hops |Packet Type|
+-----------+-----------+
| Destination |
| Address |
| (12 Octets) |
+-----------------------+
| Source |
| Address |
| (12 Octets) |
+-----------------------+
IPX PACKET HEADER
The IPX header diagram above is shown without the field alignment
details. Consider each field of the IPX header separately, and how
it typically changes.
Historically, Novell has not used the Checksum field in the IPX
Mathur & Lewis