EXP Computer S200 NetBIOS Packet Formats, IBM NetBIOS Formats When to Use NetBIOS Name Filtering

	Bridge Filtering
NetBIOS Packet Formats
Introduction
	NetBIOS Name Filtering operates only on the Microsoft or IBM-compatible
	NetBIOS implementations, which represents the majority of NetBIOS
	implementations. It does not recognize at this time Novell’s implementation of
	NetBIOS over IPX, nor does it recognize the packet format of NetBIOS over TCP
	(RFC 1000).

NetBIOS Name Filtering operates on Ethernet LANs.

IBM NetBIOS Formats

When to Use NetBIOS Name Filtering

IBM NetBIOS formats are documented in the IBM publication LAN Technical Report for IEEE 802.2 and NetBIOS Interfaces, SC-303587.

Configure NetBIOS Name Filtering when:

All of the following are true:

•The bridged packet is a MAC-level multicast or broadcast, that is, the first transmitted bit of the destination is set.

•The bridged packet contains an 802.2 LLC field (that is, on Ethernet implementation, the packet does not use an EtherType code to distinguish the packet format).

•The LLC DSAP/SSAP/CTL fields are:

0xF0 0xF0 x03

The first byte following the above LLC layer is considered offset 0 of the NetBIOS PDU (protocol data unit).

•The two bytes at NetBIOS offset 2-3 are 0xFF and 0xFE (NetBIOS frame delimiter).

Either one of the following is true:

• The NetBIOS command byte at offset 4 is:

00 (Add_Group_Name) or 01 (Add_Name Query)

The packet field to be compared to the NetBIOS Name Filter list is the SOURCE name field, occupying the 16 bytes starting an offset 0x1C in the NetBIOS PDU.

•The NetBIOS command byte at offset 4 is: 08 (Datagram) or 0x0A (Name Query)

The packet field to be compared to the NetBIOS Name Filter list is the

DESTINATION name field, occupying the 16 bytes starting at offset 0x0C of the

NetBIOS PDU.

When Filters Are NetBIOS name filters are applied to the broadcast packets that are transmitted in

Appliedorder to initiate NetBIOS sessions and to broadcast datagrams. Application of NetBIOS filters does not halt the operation of any NetBIOS sessions already in progress.

Bridging 85

T0008-16F Release 5.2M