- Internetwork Packet Exchange
Internetwork Packet Exchange (IPX) is the OSI-model Network layer protocol in the
IPX/SPX protocol stack .The IPX/SPX protocol stack is supported by Novell's
NetWare network operating system . Because of Netware's popularity through the late 1980s into the mid 1990s, IPX became a popularinternetworking protocol. Novell derived IPX fromXerox Network Services ' IDP protocol.IPX usage is in general decline as the boom of the
Internet has madeTCP/IP nearly universal. Computers and networks can run multiplenetwork protocol s, so almost all IPX sites will be running TCP/IP as well to allow for Internet connectivity [ [http://articles.techrepublic.com.com/5100-10878_11-5026038.html TechRepublic - Do you still support IPX/SPX on your Windows servers?] ] . It is also now possible to run Novell products without IPX, as they have supported both IPX and TCP/IP since NetWare reached version 5 [ [http://support.novell.com/techcenter/articles/ana19980302.html Maintaining IPX Compatibility During a Migration to TCP/IP on a NetWare Network] ] .upport
The following operating systems do not natively support IPX
*Windows Vista , both32-bit and64-bit versions
*Windows XP 64-bit [ [http://technet2.microsoft.com/windowsserver/en/library/7e7e506d-64d3-42b4-ba8a-76039c66e3be1033.mspx?mfr=true Microsoft Technet] ]
*Windows Server 2003 64-bit
*Mac OS later than 9.2.2 [ [http://us.blizzard.com/support/article.xml?articleId=21196&searchQuery=IPX&pageNumber=1 Blizzard Support - Installing the IPX network protocol on the Macintosh] ]
*OpenBSD later than 4.1 [ [http://www.openbsd.org/plus42.html OpenBSD 4.2 ChangeLog] ]IPX addressing
* Logical networks are assigned a unique 32-bit
hexadecimal address in the range of 0x1 - 0xFFFFFFFE.
* Hosts have a 48-bit node address which by default is set to the network interface card'sMAC address . The node address is appended to the network address to create a unique identifier for the host on the network.
* Network number 00:00:00:00 means current network
* Broadcast address is FF:FF:FF:FFimilarities with IP
The IPX network address is conceptually identical to the network part of the
IP address (the parts withnetmask bits set to 1); the node address then has the same meaning as the bits of IP address with netmask bits set to 0. As the node address is usually identical to the MAC address of the network adapter, theAddress Resolution Protocol is not needed.For
routing , the entries in the IPXrouting table are similar to IP routing tables; routing is done by network address, and for each network address a network:node of the next router is specified in a similar fashion an IP address/netmask is specified in IP routing tables.IPX over Ethernet
IPX can be transmitted over Ethernet using one of the following 4 encapsulation types:
*
802.3 (raw) is used in legacy systems and involves IPX data starting immediately after 802.3 frame header. The packet starts with Destination Ethernet Address (6 bytes), Source Ethernet Address (6 bytes), Frame Length (2 bytes) followed by IPX data. Latter always starts with two 0xFF bytes (Checksum field), and this can be used to differentiate this type of IPX encapsulation from next two types.*
802.2 (Novell) comprises 802.3 frame header (destination, source, length) followed by LLC header (3 bytes - 0xE0, 0xE0, 0x03) followed by IPX data. 0xE0 fields of LLC header stand for 'Novell' protocol.*
802.2 (SNAP) comprises 802.3 frame header, LLC header (3 bytes - 0xAA, 0xAA, 0x03), SNAP header (5 bytes - 0x00, 0x00, 0x00, 0x81, 0x37) and IPX data. 0xAA fields of LLC header stand for 'SNAP' protocol. First three bytes of SNAP header are OUI followed by 2 bytes of IPXEtherType .*Ethernet II comprises Ethernet II frame header (Destination, Source,
EtherType ) followed by IPX data.References
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