Network Working Group                                           M. Bakke
Request for Comments: 3721                                         Cisco
Category: Informational                                        J. Hafner
                                                              J. Hufferd
                                                            K. Voruganti
                                                                     IBM
                                                              M. Krueger
                                                         Hewlett-Packard
                                                              April 2004


           Internet Small Computer Systems Interface (iSCSI)
                          Naming and Discovery

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   This document provides examples of the Internet Small Computer
   Systems Interface (iSCSI; or SCSI over TCP) name construction and
   discussion of discovery of iSCSI resources (targets) by iSCSI
   initiators.  This document complements the iSCSI protocol document.
   Flexibility is the key guiding principle behind this document.  That
   is, an effort has been made to satisfy the needs of both small
   isolated environments, as well as large environments requiring
   secure/scalable solutions.

















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Table of Contents

   1. iSCSI Names and Addresses. . . . . . . . . . . . . . . . . . .   3
      1.1.  Constructing iSCSI names using the iqn. format . . . . .   5
      1.2.  Constructing iSCSI names using the eui. format . . . . .   8
   2. iSCSI Alias. . . . . . . . . . . . . . . . . . . . . . . . . .   8
      2.1.  Purpose of an Alias. . . . . . . . . . . . . . . . . . .   8
      2.2.  Target Alias . . . . . . . . . . . . . . . . . . . . . .   9
      2.3.  Initiator Alias. . . . . . . . . . . . . . . . . . . . .  10
   3. iSCSI Discovery. . . . . . . . . . . . . . . . . . . . . . . .  12
   4. Security Considerations. . . . . . . . . . . . . . . . . . . .  13
   5. References . . . . . . . . . . . . . . . . . . . . . . . . . .  13
      5.1.  Normative References . . . . . . . . . . . . . . . . . .  13
      5.2.  Informative References . . . . . . . . . . . . . . . . .  14
   6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  14
   Appendix A: iSCSI Naming Notes. . . . . . . . . . . . . . . . . .  15
   Appendix B: Interaction with Proxies and Firewalls. . . . . . . .  16
               B.1.  Port Redirector . . . . . . . . . . . . . . . .  16
               B.2.  SOCKS server. . . . . . . . . . . . . . . . . .  17
               B.3.  SCSI gateway. . . . . . . . . . . . . . . . . .  17
               B.4.  iSCSI Proxy . . . . . . . . . . . . . . . . . .  18
               B.5.  Stateful Inspection Firewall. . . . . . . . . .  18
   Appendix C: iSCSI Names and Security Identifiers. . . . . . . . .  19
   Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . . .  21
   Full Copyright Statement. . . . . . . . . . . . . . . . . . . . .  22


























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1.  iSCSI Names and Addresses

   The main addressable, discoverable entity in iSCSI is an iSCSI Node.
   An iSCSI node can be either an initiator, a target, or both.  The
   rules for constructing an iSCSI name are specified in [RFC3720].

   This document provides examples of name construction that might be
   used by a naming authority.

   Both targets and initiators require names for the purpose of
   identification, so that iSCSI storage resources can be managed
   regardless of location (address).  An iSCSI name is the unique
   identifier for an iSCSI node, and is also the SCSI device name [SAM2]
   of an iSCSI device.  The iSCSI name is the principal object used in
   authentication of targets to initiators and initiators to targets.
   This name is also used to identify and manage iSCSI storage
   resources.

   Furthermore, iSCSI names are associated with iSCSI nodes instead of
   with network adapter cards to ensure the free movement of network
   HBAs between hosts without loss of SCSI state information
   (reservations, mode page settings etc) and authorization
   configuration.

   An iSCSI node also has one or more addresses.  An iSCSI address
   specifies a single path to an iSCSI node and consists of the iSCSI
   name, plus a transport (TCP) address which uses the following format:

      <domain-name>[:<port>]

   Where <domain-name> is one of:

   -  IPv4 address, in dotted decimal notation.  Assumed if the name
      contains exactly four numbers, separated by dots (.), where each
      number is in the range 0..255.

   -  IPv6 address, in colon-separated hexadecimal notation, as
      specified in [RFC3513] and enclosed in "[" and "]" characters, as
      specified in [RFC2732].

   -  Fully Qualified Domain Name (host name).  Assumed if the <domain-
      name> is neither an IPv4 nor an IPv6 address.

   For iSCSI targets, the <port> in the address is optional; if
   specified, it is the TCP port on which the target is listening for
   connections.  If the <port> is not specified, the default port 3260,
   assigned by IANA, will be assumed.  For iSCSI initiators, the <port>
   is omitted.



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   Examples of addresses:

   192.0.2.2
   192.0.2.23:5003
   [FEDC:BA98:7654:3210:FEDC:BA98:7654:3210]
   [1080:0:0:0:8:800:200C:417A]
   [3ffe:2a00:100:7031::1]
   [1080::8:800:200C:417A]
   [1080::8:800:200C:417A]:3260
   [::192.0.2.5]
   mydisks.example.com
   moredisks.example.com:5003

   The concepts of names and addresses have been carefully separated in
   iSCSI:

   -  An iSCSI Name is a location-independent, permanent identifier for
      an iSCSI node.  An iSCSI node has one iSCSI name, which stays
      constant for the life of the node.  The terms "initiator name" and
      "target name" also refer to an iSCSI name.

   -  An iSCSI Address specifies not only the iSCSI name of an iSCSI
      node, but also a location of that node.  The address consists of a
      host name or IP address, a TCP port number (for the target), and
      the iSCSI Name of the node.  An iSCSI node can have any number of
      addresses, which can change at any time, particularly if they are
      assigned via DHCP.

   A similar analogy exists for people.  A person in the USA might be:

      Robert Smith
      SSN+DateOfBirth: 333-44-5555 14-MAR-1960
      Phone: +1 (763) 555.1212
      Home Address: 555 Big Road, Minneapolis, MN 55444
      Work Address: 222 Freeway Blvd, St. Paul, MN 55333

   In this case, Robert's globally unique name is really his Social
   Security Number plus Date of Birth.  His common name, "Robert Smith",
   is not guaranteed to be unique.  Robert has three locations at which
   he may be reached; two Physical addresses, and a phone number.

   In this example, Robert's SSN+DOB is like the iSCSI Name (date of
   birth is required to disambiguate SSNs that have been reused), his
   phone number and addresses are analogous to an iSCSI node's TCP
   addresses, and "Robert Smith" would be a human-friendly label for
   this person.





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   To assist in providing a more human-readable user interface for
   devices that contain iSCSI targets and initiators, a target or
   initiator may also provide an alias.  This alias is a simple UTF-8
   string, is not globally unique, and is never interpreted or used to
   identify an initiator or device within the iSCSI protocol.  Its use
   is described further in section 2.

1.1.  Constructing iSCSI names using the iqn. format

   The iSCSI naming scheme was constructed to give an organizational
   naming authority the flexibility to further subdivide the
   responsibility for name creation to subordinate naming authorities.
   The iSCSI qualified name format is defined in [RFC3720] and contains
   (in order):

   -  The string "iqn."

   -  A date code specifying the year and month in which the
      organization registered the domain or sub-domain name used as the
      naming authority string.

   -  The organizational naming authority string, which consists of a
      valid, reversed domain or subdomain name.

   -  Optionally, a ':', followed by a string of the assigning
      organization's choosing, which must make each assigned iSCSI name
      unique.

   The following is an example of an iSCSI qualified name from an
   equipment vendor:

        Organizational      Subgroup Naming Authority
                Naming      and/or string Defined by
   Type  Date     Auth      Org. or Local Naming Authority
   +--++-----+ +---------+ +--------------------------------+
   |  ||     | |         | |                                |

   iqn.2001-04.com.example:diskarrays-sn-a8675309

   Where:

      "iqn" specifies the use of the iSCSI qualified name as the
      authority.








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      "2001-04" is the year and month on which the naming authority
      acquired the domain name used in this iSCSI name.  This is used to
      ensure that when domain names are sold or transferred to another
      organization, iSCSI names generated by these organizations will be
      unique.

      "com.example" is a reversed DNS name, and defines the
      organizational naming authority.  The owner of the DNS name
      "example.com" has the sole right of use of this name as this part
      of an iSCSI name, as well as the responsibility to keep the
      remainder of the iSCSI name unique.  In this case, example.com
      happens to manufacture disk arrays.

      "diskarrays" was picked arbitrarily by example.com to identify the
      disk arrays they manufacture.  Another product that ACME makes
      might use a different name, and have its own namespace independent
      of the disk array group.  The owner of "example.com" is
      responsible for keeping this structure unique.

      "sn" was picked by the disk array group of ACME to show that what
      follows is a serial number.  They could have just assumed that all
      iSCSI Names are based on serial numbers, but they thought that
      perhaps later products might be better identified by something
      else.  Adding "sn" was a future-proof measure.