Browse Prior Art Database

Source Routing for Netbios in AIX

IP.com Disclosure Number: IPCOM000105451D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 88K

Publishing Venue

IBM

Related People

Wang, RT: AUTHOR

Abstract

A version of LAN Server is desired that runs on the AIX* platform. It interoperates with OS/2* LAN Server clients using NetBIOS protocol. Since AIX 3.2 does not support NetBIOS, a NetBIOS STREAMS module was developed to support the LAN Server. But the STREAMS mechanism provided by AIX 3.2 does not support source routing for NetBIOS. NetBIOS frames are distinguished from others by its SAP ID of 'F0' hexadecimal. This paper describes a simple solution for supporting source routing for NetBIOS.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Source Routing for Netbios in AIX

      A version of LAN Server is desired that runs on the AIX*
platform.  It interoperates with  OS/2*  LAN  Server  clients  using
NetBIOS protocol.  Since  AIX  3.2 does not support NetBIOS, a
NetBIOS STREAMS module was developed to support the LAN Server.  But
the STREAMS mechanism  provided  by AIX 3.2 does not support source
routing for NetBIOS.  NetBIOS frames are distinguished from  others
by its  SAP ID of 'F0' hexadecimal.  This paper describes a simple
solution for supporting source routing for NetBIOS.

      Source Routing is the mechanism by which a workstation on one
Local Token Ring can communicate with another workstation on a
different local Token Ring through bridges.  A  workstation  is
identified by a unique 6-byte Token Ring address.  When sending a
frame, both the destination and  the  source  addresses  are
specified.   However,  without  the source routing, a frame can not
leave the local ring.  Source  routing information,  when present, is
indicated by the Routing Information Indicator (RII) bit, and the
routing  information  is  appended  to the source  address.   Thus
the source address is a variable length between 6 and 24 bytes.
Bridges use the routing information to transfer frames  from  one
local ring to another until finally reaching the target workstation.

      AIX  3.2  provides   the   STREAMS   mechanism   which   allows
communication protocol developers to develop protocol stacks in a
modular fashion.  A transport  provider  module  communicates with
the TIMOD  module  above  via  the  Transport  Provider Interface
(TPI), and with the DLPI module  below  via  the  DLC Provider
Interface  (DLPI).  TIMOD communicates with the user through
Transport Layer Interface (TLI).

      To send a  frame,  the  transport  provider  passes  a  message
containing  a  dl_unitdata_req_t  structure to the DLPI module.  The
dl_unitdata_req_t structure is as follows:

     typedef struct {
       ulong  dl_primitive;        /*  DL_UNITDATA_REQ
*/
       ulong  dl_dest_addr_length; /* Length of destination address
*/
       ulong  dl_dest_addr_offset; /* Offset to address
*/
       ulong  dl_priority_t dl_priority; /*
*/
     } dl_unitdata_req_t;

      The dl_primitive field contians  the  DL_UNITDATA_REQ  command.
The  dl_dest_addr_offset  field points to the partners address,  and
the dl_dest_addr_length is the  address  length  in  bytes.  For
Token  Ring,  the dl_dest_addr_length is normally 6 bytes.  And
currently, DLPI always defaults the address length to 6.

When DLPI receives a  frame  from  the  network  interface,  it
passe...