DHC Josh Tseng
Internet Draft Nishan Systems
<draft-tseng-dhc-isnsoption-00.txt>
Expires August 2002 February 2002
DHCP Options for Internet Storage Name Service
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of [RFC2026].
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Comments
Comments should be sent to the IPS mailing list (ips@ece.cmu.edu) or
to the authors.
Table of Contents
Status of this Memo...................................................1
Comments..............................................................1
Abstract..............................................................2
Conventions used in this document.....................................2
1.Introduction.......................................................2
2.iSNS Option for DHCP...............................................3
3.Security Considerations............................................4
4.References.........................................................4
5.Author's Addresses.................................................5
Full Copyright Statement..............................................6
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DHCP Option Number for iSNS February 2002
Abstract
This document proposes a new DHCP option number to allow iSCSI and
iFCP devices using DHCP to discover the location of the iSNS server.
iSNS provides discovery and management capabilities for iSCSI and
Fibre Channel (FCP) storage devices in an enterprise-scale IP
storage network. iSNS provides intelligent storage management
services comparable to those found in Fibre Channel networks,
allowing a commodity IP network to function in a similar capacity as
a storage area network.
Conventions used in this document
iSNS refers to the framework consisting of the storage network model
and associated services.
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 [RFC2119].
All frame formats are in big endian network byte order.
This document uses the following terms:
"iSNS Client" - iSNS clients are processes resident in iSCSI and
iFCP devices that initiate transactions with the iSNS server using
the iSNS Protocol.
"iSNS Server" - The iSNS server responds to iSNS protocol query and
registration messages, and initiates asynchronous notification
messages. The iSNS server stores information registered by iSNS
clients.
"iSCSI (Internet SCSI)" - iSCSI is an encapsulation of SCSI for a
new generation of storage devices interconnected with TCP/IP.
"iFCP (Internet Fibre Channel Protocol)" - iFCP is a gateway-to-
gateway protocol designed to interconnect existing Fibre Channel and
SCSI devices using TCP/IP. iFCP maps the existing FCP standard and
associated Fibre Channel services to TCP/IP.
1. Introduction
The Dynamic Host Configuration Protocol provides a framework for
passing configuration information to hosts. Its usefulness extends
to hosts and devices using the iSCSI and iFCP protocols to connect
to block level storage assets over a TCP/IP network.
The iSNS Protocol provides a framework for automated discovery,
management, and configuration of iSCSI and iFCP devices on a TCP/IP
network. It provides functionality similar to that found on Fibre
Channel networks, except that iSNS works within the context of an IP
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DHCP Option Number for iSNS February 2002
network. iSNS thereby provides the requisite storage intelligence
to IP networks that are standard on existing Fibre Channel networks.
Existing DHCP option numbers are not plausible due to the following
reasons:
1) iSNS functionality is distinctly different from other protocols
using existing DHCP option numbers. Specifically, iSNS provides a
significant superset of capabilities compared to typical name
resolution protocols such as DNS. It is designed to support client
devices that allow themselves to be configured and managed from a
central iSNS server.
2) iSNS requires a DHCP option format that provides more than the
location of the iSNS server. The DHCP option number needs to
specify the subset of iSNS services that will be actively used by
the iSNS client.
The proposed DHCP option for iSNS is used by iSCSI and iFCP devices
to discover the location of the iSNS server. Although a standard
one-byte DHCP option number is strongly desired, the assignment of a
two-byte option number implemented by options 126 and 127 is
acceptable.
2. iSNS Option for DHCP
This option specifies the location of the primary and backup iSNS
servers and the subset of iSNS services that will be used by the
iSNS client.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code = TBD | Length | Usage | Heartbeat |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| a1 | a2 | a3 | a4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| b1 | b2 | b3 | b4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The iSNS Option specifies a list of IP addresses used by iSNS
servers.
Length indicates the number of bytes that follow the Length field.
The minimum value for the Length field is 2 in order to account for
the Usage and Heartbeat bytes.
The Usage byte indicates whether the DHCP option overrides the
static configuration of the iSCSI or iFCP device, as well as the
subset of iSNS features that are to be used by the iSNS client
device. The following table indicates how iSNS is to be used by the
DHCP client.
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DHCP Option Number for iSNS February 2002
Value iSNS Usage
----- ----------
0 DISCOVERY Only
1 DISCOVERY and AUTHORIZATION
3 DISCOVERY, AUTHORIZATION and SECURITY
All other values are reserved and should not be used
A Usage byte value of 0 indicates that iSNS is to be used for
discovery only, and that static or manual configuration of the iSCSI
or iFCP device overrides any discovery or configuration information
found in the iSNS server through iSNS protocol messages. Although
the Discovery Domain/Zoning features of the iSNS may be used to
manage the discovery process, Discovery Domain membership does not
indicate authorization to establish a session with any storage
device.
A Usage byte value of 1 indicates that iSNS is used for both
discovery and authorization. Information discovered from the iSNS
server overrides any static or manual configuration of the iSCSI or
iFCP device. The Discovery Domain/Zoning membership configuration
stored in the iSNS provide authorizations that determine whether
storage sessions may be established between peer devices.
A Usage byte value of 3 indicates that in addition to discovery and
authorization, the iSNS is used to distribute IKE/IPSec security
policy configuration to iSCSI and/or iFCP devices.
The Heartbeat byte determines if the IP address indicated in a1-a4
is the iSNS heartbeat multicast address.
If the Heartbeat byte is 0, then then a1-a4 is the IP address of the
primary iSNS server. Any additional IP addresses are the iSNS
backup servers, listed in order of precedence.
If the Heartbeat byte is 1, then a1-a4 is the iSNS heartbeat
multicast address, b1-b4 is the primary iSNS server IP address, and
any following IP addresses are the iSNS backup servers listed in
order of precedence.
3. Security Considerations
DHCP currently provides no authentication or security mechanisms.
Potential exposures to attack are discussed in section 7 of the DHCP
protocol specification [DHCP].
iSNS security considerations are discussed in [iSNS] and [SEC-IPS].
4. References
[DHCP] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, Bucknell University, March 1997.
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DHCP Option Number for iSNS February 2002
[iSCSI] Satran, J., et al., "iSCSI", Internet draft (work in
progress), draft-ietf-ips-iSCSI-10.txt, January 2002
[iFCP] Monia, C., et al., "iFCP - A Protocol for Internet Fibre
Channel Storage Networking", Internet draft (work in
progress), draft-ietf-ips-ifcp-09.txt, January 2002
[iSNS] Tseng, J. et al., "iSNS - Internet Storage Name
Service", Internet draft (work in progress), draft-ietf-
ips-isns-08.txt, February 2002
[SEC-IPS] Aboba, B., et al., "Securing IP Block Storage
Protocols", draft-ietf-ips-security-09.txt, February
2002
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997
5. Author's Addresses
Josh Tseng
Nishan Systems
3850 North First Street
San Jose, CA 95134-1702
Phone: (408) 519-3749
Email: jtseng@nishansystems.com
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Internet Storage Name Service (iSNS) November 2001
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Internet Storage Name Service (iSNS) November 2001
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