分类： 系统运维
2009-05-13 14:22:11
To communicate, each node (computer, printer, router etc) needs to be uniquely identified on a network. Within the TCP/IP suite of protocols, under the IPv4 address scheme, a 32 bit address identifies each node and the network it is connected to. In IPX/SPX networks, a 48 bit address identifies a node on a network and a 32 bit address identifies each network. In NetBIOS networks names are used by each node.
NetBIOS names are 16 bytes long (padded if necessary) and there are very few restraints on the byte values which can be used. Non-alphanumeric characters can be used in NetBIOS names, although some implementations may not support this and applications using NetBIOS may impose other constraints.
Often an implementation will make use of the 16th byte, for example to indicate a particular service; thus the 16th byte may be used in a way which is broadly analogous to port numbers in TCP/IP.
It is worth noting that SMB / CIFS names map directly on to NetBIOS names and in this case the 16th byte is particularly important for identifying various services.
NetBIOS names represent a flat name space; names are non-hierarchical with no provision for subdivision. Because there is no provision for identifying networks with the NetBIOS name scheme, protocols using this name scheme can not be routed.
A NetBios name is often associated with one end of a session between two nodes.
A station on the network can be known by several names (aliases) originally up to 12 (**1) or 17 (**2) names. Modern implementations allow very many names to be used. Names can be unique names reserved for the station's exclusive use or group names shared with other stations. One name is the permanent node name which is the physical adapter card's name; this is usually derived from the Media Access Control (MAC) address of the card i.e. the hardware address and consists of 10 bytes of zeros followed by the 6 bytes of the MAC address. This special permanent node name is often called "NETBIOS_NAME_1". It is because one of the names incorporates the physical MAC address (and because there is only one network) that there is often no name resolution protocol (analogous to the Address Resolution Protocol ARP in TCP/IP networks).
When NetBIOS is encapsulated within other protocols such as IPX/SPX or TCP/IP there is a mechanism for mapping NetBIOS names to the address schemes of the encapsulating protocol. See the section on Encapsulation .
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