Fully parse IPX protocol

In the study of network protocols, I have made a mistake by mistake to confuse the IP protocol and IPX protocol. In fact, the two are quite different. Now let's learn more about IPX. IPX (Internet work Packet Exchange) is a dedicated protocol cluster mainly used by the Novell NetWare operating system. IPX is the layer-3 protocol in the IPX protocol cluster.

The following describes the key points of the IPX protocol, which are used as preparations for IPX-related experiments.

1. Protocol composition of IPX

The IPX protocol cluster includes the following main Protocols:

◆ IPX: layer-3 protocol used to select and forward packets over the Internet. It specifies a connectionless datagram, which is equivalent to the IP protocol in the TCP/IP protocol cluster;

◆ SPX: Sequenced Packet Exchange Protocol. Is the layer-4 connection-oriented protocol in the IPX protocol cluster, which is equivalent to the TCP protocol in the TCP/IP protocol cluster;

◆ NCP: the NetWare Core Protocol, which provides connections and applications from the customer to the server;

◆ SAP: Service Advertising Protocol, used to advertise network services on the IPX network;

◆ Ipx rip: Routing Information Protocol (Routing Information Protocol) to exchange route Information between routers and form a route table.

2. IPX addressing

The IP address length of the IPX network is 80 bits (bit, which consists of two parts: the first part is the 32-bit network number, and the second part is the 48-bit node number. The IPX address is usually expressed in hexadecimal notation.

The IPX network number is assigned by the network administrator and can be defined as needed.

The IPX node number is usually the MAC address of the network interface.

3. encapsulation of IPX protocol over Ethernet

The IPX protocol supports the following four encapsulation formats, also known as frame formats, over Ethernet:

◆ Ethernet 802.3: it is also called the original Ethernet, which is called "novell-ether" in Cisco devices. It is the default frame format between NetWare versions 2 and 3.1;

◆ Ethernet 802.2, also known as sap, is a standard IEEE frame format. It is a standard frame format between NetWare 3.12 and 4.x;

◆ Ethernet II, also known as arpa, adopts the Header Format of the standard Ethernet Version II;

◆ Ethernet SNAP, or snap, extended the IEEE 802.2 Header Format by adding a Network Access Protocol (SNAP.

Devices in different IPX encapsulation formats cannot communicate with each other.

4. IPX service announcement

SAP is an ipx service announcement protocol that can advertise the addresses and services of network resource devices, such as network servers and print servers.

A vro can listen to SAP update messages and create a table of known services and corresponding network addresses. The client can use the SAP table on the vro to obtain information about the online services and addresses, so as to directly access the corresponding services.