IPX
Encyclopedia
Internetwork Packet Exchange (IPX) is the OSI-model
Network layer
protocol in the IPX/SPX
protocol stack
.
The IPX/SPXM 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 popular internetworking
protocol. Novell derived IPX from Xerox Network Systems' IDP protocol.
IPX was not scalable enough for large networks such as the internet and as such, IPX usage decreased as the boom of the Internet
made TCP/IP nearly universal. Computers and networks can run multiple network protocols, so almost all IPX sites will be running TCP/IP as well to allow for Internet connectivity. 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 in late 1998.
(the parts with netmask 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, the Address Resolution Protocol
is not needed.
For routing
, the entries in the IPX routing 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.
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
Network layer
Network layer
The network layer is layer 3 of the seven-layer OSI model of computer networking.The network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.The network...
protocol in the IPX/SPX
IPX/SPX
IPX/SPX stands for Internetwork Packet Exchange/Sequenced Packet Exchange. IPX and SPX are networking protocols used primarily on networks using the Novell NetWare operating systems.-Protocol Layers:...
protocol stack
Protocol stack
The protocol stack is an implementation of a computer networking protocol suite. The terms are often used interchangeably. Strictly speaking, the suite is the definition of the protocols, and the stack is the software implementation of them....
.
The IPX/SPXM protocol stack is supported by Novell's NetWare network operating system
Network operating system
A networking operating system , also referred to as the Dialoguer, is the software that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions...
. Because of Netware's popularity through the late 1980s into the mid 1990s, IPX became a popular internetworking
Internetworking
Internetworking is the practice of connecting a computer network with other networks through the use of gateways that provide a common method of routing information packets between the networks...
protocol. Novell derived IPX from Xerox Network Systems' IDP protocol.
IPX was not scalable enough for large networks such as the internet and as such, IPX usage decreased as the boom of the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
made TCP/IP nearly universal. Computers and networks can run multiple network protocols, so almost all IPX sites will be running TCP/IP as well to allow for Internet connectivity. 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 in late 1998.
IPX addressing
- Logical networks are assigned a unique 32-bit hexadecimalHexadecimalIn mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
address in the range of 0x1 - 0xFFFFFFFE. - Hosts have a 48-bit node address which by default is set to the network interface card's MAC addressMAC addressA Media Access Control address is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies, including Ethernet...
. 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:FF
Similarities with IP
The IPX network address is conceptually identical to the network part of the IP addressIP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
(the parts with netmask 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, the Address Resolution Protocol
Address Resolution Protocol
Address Resolution Protocol is a telecommunications protocol used for resolution of network layer addresses into link layer addresses, a critical function in multiple-access networks. ARP was defined by RFC 826 in 1982. It is Internet Standard STD 37...
is not needed.
For routing
Routing
Routing is the process of selecting paths in a network along which to send network traffic. Routing is performed for many kinds of networks, including the telephone network , electronic data networks , and transportation networks...
, the entries in the IPX routing table
Routing table
In computer networking a routing table, or Routing Information Base , is a data table stored in a router or a networked computer that lists the routes to particular network destinations, and in some cases, metrics associated with those routes. The routing table contains information about the...
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 (SNAPSubnetwork Access ProtocolThe Subnetwork Access Protocol is a mechanism for multiplexing, on networks using IEEE 802.2 LLC, more protocols than can be distinguished by the 8-bit 802.2 Service Access Point fields. SNAP supports identifying protocols by Ethernet type field values; it also supports vendor-private protocol...
) 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 OUIOrganizationally Unique IdentifierAn Organizationally Unique Identifier is a 24-bit number that is purchased from the Institute of Electrical and Electronics Engineers, Incorporated Registration Authority...
followed by 2 bytes of IPX EtherTypeEtherTypeEtherType is a two-octet field in an Ethernet frame. It is used to indicate which protocol is encapsulated in the PayLoad of an Ethernet Frame. This field was first defined by the Ethernet II framing networking standard, and later adapted for the IEEE 802.3 Ethernet networking standard.EtherType...
.
- Ethernet II comprises Ethernet II frame header (Destination, Source, EtherTypeEtherTypeEtherType is a two-octet field in an Ethernet frame. It is used to indicate which protocol is encapsulated in the PayLoad of an Ethernet Frame. This field was first defined by the Ethernet II framing networking standard, and later adapted for the IEEE 802.3 Ethernet networking standard.EtherType...
) followed by IPX data.