Avaya Configuring IP Utilities Uživatelský manuál stáhnout pdf (Strana 59)

Overview of IP Utilities

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• Use a server’s NetBIOS name to determine the server’s network address. The

application issues a name query request to NetBIOS, containing the target

server’s NetBIOS name. NetBIOS broadcasts the name query request. The

server that recognizes the name returns a name query response containing its

network address.

The NetBIOS session service allows an application to conduct a reliable,

sequenced exchange of messages with another application. The messages can be

up to 131,071 bytes long.

The NetBIOS datagram service allows an application to exchange datagrams with

a specific application or to broadcast datagrams to a group and receive datagrams

from the group. Datagrams allow applications to communicate without

establishing a session. When a NetBIOS application wants to send information

that does not require acknowledgment from the destination application, the

application can transmit a NetBIOS datagram.

NetBIOS in an IP Environment

The NetBIOS name service and datagram service rely on the capability of the

underlying network to broadcast name query requests to all NetBIOS applications.

In a NetBIOS over IP environment, it is the responsibility of the IP router to

ensure that the broadcast queries reach all appropriate network segments. To do

this, the router:

1. Analyzes each NetBIOS packet received on any NetBIOS interface to

determine whether the packet is a broadcast packet

2. Rebroadcasts each broadcast packet out all appropriate interfaces, except the

one on which it was received (readdressing the packet if required)

If alternate paths exist between different network segments, broadcasting loops

can occur. To prevent such loops, the router:

1. Stamps the data portion of the IP packet with the IP address of the router from

which the packet was rebroadcast

2. Parses the IP addresses included in the data portion of the IP packet to

determine if the packet has already been rebroadcast by that router

In Figure 2-8

, for example, client C on the network connected to router B wishes

to communicate with server S, which is located on the network connected to

router A.

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Avaya Configuring IP Utilities Uživatelský manuál Strana 59