Concepts and Principles of Operation
IPX
IPX is the protocol used by Novel Netware as the network layer protocol. Novel IPX also uses Routing Information Protocol (RIP) for routing protocol. The IPX address consists of two parts: a 4- byte network number, and a 6- byte node number. Often, the node number is assigned as the Ethernet MAC address. In a bridging environment, all Netware clients and servers share the same external network number. In an IPX routing environment, networks connected by IPX routers are assigned with unique IPX network numbers.
An IPX client wishing to connect to a Netware server first sends a “find nearest server” request trying to locate a server. After the server's response to the request, the Netware client login process may begin. If a Netware server is not locally connected to the client’s network, the router connecting to the client’s network is responsible for responding to the “find nearest server” request. A router such as Hypertec ISDN 10T Router learns of the existence of a remote server by manual configuration, and through Service Advertising Protocol (SAP).
Router
client
Internal IPX net:
Router
server
IPX Address
external network
Netware 3.x and later use the notations of external IPX address and internal IPX address. Any Netware device physically connected to a network have an external IPX address. A Netware server such as a file server is also assigned with an internal IPX address. The internal address refers to the internal network within a server allowing internal processes to communicate. All external and internal addresses must be unique from one another.
IPX Frame Type
The IPX frames can be encoded in 4 frame types of the following formats:
Ethernet II (0x81,0x37,...),
802.3 (length, 0xFF, 0xFF,....),
802.2 (length, 0xE0, 0xE0, 0x03, 0xFF, 0xFF,......), and
SNAP (length, 0xAA, 0xAA, 0x03, 0x00, 0x00, 0x00, 0x81, 0x37,...).
Among them, 802.3 and 802.2 are two most commonly used format. Hypertec ISDN 10T Router routes only IPX traffic of certain frame type. Other frame type of IPX traffic may be bridged if so enabled.
11
