Internet Engineering Task Force                               J. Luciani
INTERNET DRAFT                                              Novell, Inc.
                                                        10 February 1998


              DHCP Options for Novell IPX Compatibility
                    draft-ietf-dhc-ipxcmd-00.txt


Status of This Memo

   This document is a submission to the Dynamic Host Configuration
   Working Group of the Internet Engineering Task Force (IETF). Comments
   should be submitted to the dhcp-v4@bucknell.edu mailing list.

   Distribution of this memo is unlimited.

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Abstract

   This document defines a new DHCP option for delivering configuration
   information to hosts utilizing the IPX Compatibility feature of       
   Novell's NetWare.  The option carries several operational parameters  
   that allow network administrators to customize their installations.
















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1. Introduction

   The IPX Compatibility feature of Novell's NetWare systems is a tool   
   that can be used by network administrators to migrate their IPX based 
   networks to IP based networks.

   The IPX Compatibility feature provides the connectivity necessary for 
   IPX Client/Server applications to communicate between nodes that      
   connect to the IP Internet (IP Nodes).  The IPX Compatibility feature 
   also allows IPX Client/Server applications to communicate between IP  
   Nodes and nodes that connect to IPX networks (IPX Nodes).

   Connectivity between IPX Nodes and IP Nodes is achieved through the   
   use of gateways called Migration Agents.

   This specification describes a DHCP option [1] that can carry one or
   several IPX Compatibility configuration parameters.  Each             
   configuration parameter is treated as a separate sub-option by the    
   hosts.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119. [2]

2. IPX Compatibility Option

   This option specifies one or more sub-options carrying IPX            
   Compatibility information.  The sub-options that can be carried by    
   this option are described in the sections that follow.

   The code for this option is ??, and its maximum length is 255 octets.

      Code   Len        Sub-Option 1               Sub-Option 2
     +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--
     |  ?? |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  a3 |  a4 |  ...
     +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--

   The 'Len' field specifies the number of octets containing sub-option
   information within the DHCP option.

   Each sub-option will contain a code followed by a length that
   specifies the number of octets containing configuration parameter
   information within the sub-option.

      Sub    Sub 
      Code   Len        Configuration Parameter(s)
     +-----+-----+-----+-----+-----+-----+-----+-----+--
     |  x  |  n  |  a1 |  a2 |  a3 |  a4 |  a6 |  a7 |  ...
     +-----+-----+-----+-----+-----+-----+-----+-----+--



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2.1 IPX Compatibility Virtual Network Number Sub-Option

   This sub-option specifies the network number of the virtual IPX       
   network created by the IPX Compatibility feature.

   The code for this sub-option is 1. The length specified in the 'Len'  
   field of this sub-option MUST always be 4 octets.

      Code   Len    IPX Network Number
     +-----+-----+-----+-----+-----+-----+
     |  1  |  4  |  a1 |  a2 |  a3 |  a4 |
     +-----+-----+-----+-----+-----+-----+

2.2 IPX Compatibility Stale Time Sub-Option

   This sub-option specifies the minimum interval in minutes that must   
   expire before hosts try to refresh their Migration Agent addressing   
   information.  This sub-option is ignored by hosts when the Migration  
   Agent sub-option is carried along with this DHCP option.

   A Stale Time of zero indicates that hosts should not refresh their    
   Migration Agent addressing information.

   The code for this sub-option is 2. The length specified in the 'Len'  
   field of this sub-option MUST always be 2 octets.

      Code   Len  Stale Time
     +-----+-----+-----+-----+
     |  2  |  2  |  a1 |  a2 |
     +-----+-----+-----+-----+

2.3 Migration Agents Sub-Option

   This option specifies the addresses of one or more Migration Agent    
   servers for the IP Nodes to use for communicating with IPX Nodes.

   The code for this sub-option is 3.  The minimum length specified in   
   the 'Len' field is 4 octets, and this length MUST be a multiple of 4.

      Code   Len        Address 1               Address 2
     +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--
     | 3   |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  a3 |  a4 |  ...
     +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--









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3. Examples

   The sections that follow illustrate the encoding of different sets
   of information within the IPX Compatibility option.

3.1 Option ?? Carrying Virtual Network Number and Stale Time Information

   The option ?? encoding shown below specifies the value 0x00ABCDEF as
   the IPX Compatibility Virtual Network Number parameter and the value
   0x0014 (20 minutes) as the IPX Compatibility Stale Time parameter.

      Code   Len
     +-----+-----+
     | ??  |  0A |
     +-----+-----+

                 IPX Compatibility Virtual Network Number Sub-Option
                 +-----+-----+-----+-----+-----+-----+
                 | 01  |  04 |  00 |  AB |  CD |  EF |
                 +-----+-----+-----+-----+-----+-----+

                 IPX Compatibility Stale Time Sub-Option
                 +-----+-----+-----+-----+
                 | 02  |  02 |  00 |  14 |
                 +-----+-----+-----+-----+

3.2 Option ?? Carrying Migration Agent Addressing Information

   The option ?? encoding shown below specifies the addresses
   137.65.147.87 (0x89419357) and 137.65.147.68 (0x89419344) as the
   addreses of Migration Agent servers.

      Code   Len
     +-----+-----+
     | ??  |  0A |
     +-----+-----+

                 Migration Agents Sub-Option
                 +-----+-----+-----+-----+-----+-----+
                 | 03  |  08 |  89 |  41 |  93 |  57 |
                 +-----+-----+-----+-----+-----+-----+

                             +-----+-----+-----+-----+
                             | 89  |  41 |  93 |  44 |
                             +-----+-----+-----+-----+







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4. References

   [1] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
       Extensions", RFC-2132, March 1997.

   [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
       Levels", RFC-2119, March 1997.

   [3] Droms, R., "Dynamic Host Configuration Protocol", RFC-2131,
       March 1997.

5. Security Considerations

   DHCP currently provides no authentication or security mechanisms.
   Potential exposures to attack are discussed in section 7 of the DHCP
   protocol specification [3]. In particular, these DHCP options allow
   an unauthorized DHCP server to misdirect an IPX Compatibility Node to
   a nonexistent Migration Agent server or to utilize an invalid IPX
   Virtual Network Number.

6. Author's Address

   Juan Carlos Luciani
   Novell, Inc.
   122 E. 1700 S.
   Provo, Utah, 84606

   Phone: +1 801 222 6000

   EMail: jluciani@Novell.Com






















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