IPS Working Group David Peterson
INTERNET-DRAFT SBS Technologies
<draft-ietf-ips-fcip-slp-08.txt> January 2004
Expires: July 2004
Category: standards-track
Finding FCIP Entities Using SLPv2
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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Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document defines the use of Service Location Protocol, version 2
(SLPv2) [RFC2608], by FCIP Entities [FCIP].
1. Introduction
This document describes the use of SLPv2 to perform dynamic discovery
of participating FCIP Entities. Implementation guidelines, service
type templates, and security considerations are specified.
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2. Notation Conventions
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].
3. Terminology
Here are some definitions that may aid readers that are unfamiliar
with either SLP, or FCIP. Some of these definitions have been
reproduced from [RFC2608] and [RFC3105].
User Agent (UA) A process working on the client's behalf
to establish contact with some service.
The UA retrieves service information from
the Service Agents or Directory Agents.
Service Agent (SA) A process working on behalf of one or more
services to advertise the services and
their capabilites.
Directory Agent (DA) A process which collects service
advertisements. There can only be one DA
present per given host.
Scope A named set of services, typically making
up a logical administrative group.
Service Advertisement A URL, attributes, and a lifetime
(indicating how long the advertisement is
valid), providing service access
information and capabilities description
for a particular service.
FCIP Entity The principle FCIP interface point to the
IP network.
FCIP Entity Name The world wide name of the switch if the
FCIP Entity resides in a switch or the
world wide node name of the associated
Nx_Port.
FCIP Discovery Domain The FCIP Discovery Domain specifies which
FCIP Entities are allowed to discover each
other within the bounds of the scope.
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4. Using SLPv2 for FCIP Service Discovery
At least two FCIP Entities must be involved in the entity discovery
process. The end result is that an FCIP Entity will discover one or
more peer FCIP Entities.
4.1. Discovering FCIP Entities using SLPv2
The following diagram shows the relationship between FCIP Entities
and their associated SLPv2 agents.
+--------------------------------------+
| FCIP Entity |
+----------------------------------+ |
| FCIP Control and Services Module | |
+----------------+ | |
| SA | UA | | |
+----------------+-----------------+ |
| TCP/UDP/IP | |
+----------------+-----------------+ |
| Interface | |
| 192.0.2.10 | |
+----------------+-----------------+---|
|
+------------+ |
| SLPv2 DA |----+ IP Network
+------------+ |
|
+----------------+-----------------+---|
| Interface | |
| 192.0.2.20 | |
+----------------+-----------------+ |
| TCP/UDP/IP | |
+----------------+-----------------+ |
| SA | UA | | |
+----------------+ | |
| FCIP Control and Services Module | |
+--------------------------------- + |
| FCIP Entity |
+--------------------------------------+
Fig. 1 FCIP Entity and SLPv2 Agent Relationship.
As indicated in the drawing above, each FCIP Entity contains an FCIP
Control and Services Module that interfaces to an SLPv2 SA and UA.
The SA constructs a service advertisement of the type
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"service:fcip:entity" for each of the service URLs it wishes to
register. The service advertisement contains a lifetime, along with
other attributes defined in the service template.
The remainder of the discovery process is identical to that used by
any client/server pair implementing SLPv2:
1. If an SLPv2 DA is found [RFC2608], the SA contacts the DA and
registers the service advertisement. Whether or not one or more SLPv2
DAs are discovered, the SA maintains the service advertisement itself
and answers multicast UA queries directly.
2. When the FCIP Entity requires contact information for a peer FCIP
Entity, the UA either contacts the DA using unicast or the SA using
multicast using an SLPv2 service request. The UA service request
includes a query, based on the attributes, to indicate the
characteristics of the peer FCIP Entities it requires.
3. Once the UA has the IP address and port number of a peer FCIP
Entity, it may begin the normal connection procedure, as described in
[FCIP], to a peer FCIP Entity.
The use of a DA is RECOMMENDED for SLPv2 operation in an FCIP
environment.
4.1.1. FCIP Discovery Domains
The concept of a discovery domain provides further granularity of
control of allowed discovery between FCIP Entities within a specific
SLPv2 scope.
The following example diagram shows the relationship between FCIP
Entities and their associated discovery domains within a specified
SLPv2 scope.
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=================fcip=======================================
= =
= *************************purple*********************** =
= * * =
= * #####orange###################### * =
= * # ------------ //////blue//////+/////////////// * =
= * # | FCIP | / # / * =
= * # | Entity A | / # / * =
= * # ------------ / # ------------ / * =
= * # / # | FCIP | / * =
= * # / # | Entity C | / * =
= * # / ------------ # ------------ / * =
= * # / | FCIP | # / * =
= * # / | Entity B | # / * =
= * # / ------------ # / * =
= * ################+################ / * =
= * //////////////////////////////// * =
= * * =
= ****************************************************** =
= =
============================================================
Fig. 2 FCIP Entity and Discovery Domain Example.
Within the specified scope "fcip", the administrator has defined a
discovery domain "purple", allowing FCIP Entities A, B, and C to
discover each other. This discovery domain is illustrated using the
"*" character.
Within the specified scope "fcip", the administrator has defined a
discovery domain "orange", allowing FCIP Entity A to discover FCIP
Entity B, but not FCIP Entity C. This discovery domain is
illustrated using the "#" character.
Within the specified scope "fcip", the administrator has defined a
discovery domain "blue", allowing FCIP Entity C to discover FCIP
Entity B, but not FCIP Entity A. This discovery domain is
illustrated using the "/" character.
For this example, the value of the fcip-discovery-domain attribute
for each FCIP Entity is as follows:
FCIP Entity A = orange,purple
FCIP Entity B = orange,blue,purple
FCIP Entity C = blue,purple
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4.2. NAT and NAPT Considerations
Since SLPv2 provides IP address and TCP port information within its
payload, the addresses an SA or DA advertise may not be the same as
those a UA must use if a Network Address(/Port) Translation
(NAT/NAPT) device is present between the UA and the SA. This may
result in the UA discovering address information that is unusable.
Below are a few recommendations to handle this:
- A fully-qualified domain name (i.e., not an IP address) SHOULD be
used in service URLs and mgmt-entity attribute.
- Use the default IANA-assigned FCIP TCP port number in service URLs,
when possible.
- If advertising service URLs through a translating device (e.g., a
NAT/NAPT device), and the FQDN, IP address, or TCP port will be
translated, the translating device can provide an SLPv2 proxy
capability to do the translation.
5. FCIP SLPv2 Templates
Two templates are provided: an FCIP Entity template, and an abstract
template to provide a means to add other FCIP related templates in
the future.
5.1. The FCIP Abstract Service Type Template
This template defines the abstract service "service:fcip". It is used
as a top-level service to encapsulate all other FCIP related
services.
Name of submitter: David Peterson
Language of service template: en
Security Considerations:
See the security considerations of the concrete service type.
Template Text:
-------------------------template begins here-----------------------
template-type=fcip
template-version=0.1
template-description=
This is an abstract service type. The purpose of the fcip service
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type is to encompass all of the services used to support the FCIP
protocol.
template-url-syntax =
url-path= ; Depends on the concrete service type.
--------------------------template ends here------------------------
5.2. The FCIP Entity Concrete Service Type Template
This template defines the service "service:fcip:entity". A device
containing FCIP Entities that wishes to have them discovered via
SLPv2 would register each of them, with each of their addresses, as
this service type.
FCIP Entities wishing to discover other FCIP Entities in this manner
will generally use one of the following example query strings:
1. Find a specific FCIP Entity, given its FCIP Entity Name:
Service: service:fcip:entity
Scope: fcip-entity-scope-list
Query: (fcip-entity-name=\ff\10\00\00\60\69\20\34\0C)
2. Find all of the FCIP Entities within a
specified FCIP Discovery Domain:
Service: service:fcip:entity
Scope: fcip-entity-scope-list
Query: (fcip-discovery-domain=fcip-discovery-domain-name)
3. In addition, a management application may wish to discover
all FCIP Entities:
Service: service:fcip:entity
Scope: management-service-scope-list
Query: none
Name of submitter: David Peterson
Language of service template: en
Security Considerations: see later section.
Template Text:
-------------------------template begins here-----------------------
template-type=fcip:entity
template-version=0.1
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template-description=
This is a concrete service type. The fcip:entity service type is
used to register individual FCIP Entity addresses to be discovered
by others. UAs will generally search for these by including one of
the following:
- the FCIP Entity Name for which an address is needed
- the FCIP Discovery Domain Name for which addresses are requested
- the service URL
template-url-syntax =
url-path = hostport
hostport = host [ ":" port ]
host = hostname / hostnumber
hostname = *( domainlabel "." ) toplabel
alphanum = ALPHA / DIGIT
domainlabel = alphanum / alphanum * [alphanum / "-"] alphanum
toplabel = ALPHA / ALPHA * [ alphanum / "-" ] alphanum
hostnumber = ipv4-number
ipv4-number = 1*3DIGIT 3("." 1*3DIGIT)
port = 1*DIGIT
;
; A DNS host name should be used along with the well-known
; IANA FCIP port number for operation with NAT/NAPT devices.
;
; Examples:
; service:fcip:entity://host.example.com
; service:fcip:entity://192.0.2.0:4000
;
fcip-entity-name = opaque L
# If the FCIP Entity is a VE_Port/B_Access implementation [FC-BB-2]
# residing in a switch, the fcip-entity-name is the Fibre Channel
# Switch Name [FC-SW-2]. Otherwise, the fcip-entity-name is the
# Fibre Channel Node Name [FC-FS] of the port (e.g., an Nx_Port)
# associated with the FCIP Entity.
# An entity representing multiple endpoints must register each of
# the endpoints using SLPv2.
transports = string M L
tcp
# This is a list of transport protocols that the registered entity
# supports. FCIP is currently supported over TCP only.
tcp
mgmt-entity = string M O L
# The URL's of the management interface(s) appropriate for SNMP,
# web-based, or telnet management of the FCIP Entity.
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# Examples:
# snmp://192.0.2.0
# http://fcipentity.example.com:1080/
# telnet://fcipentity.example.com
fcip-discovery-domain = string M L
fcip
# The fcip-discovery-domain string contains the name(s) of the FCIP
# discovery domain(s) to which this FCIP Entity belongs.
--------------------------template ends here------------------------
6. Security Considerations
The SLPv2 security model as specified in [RFC2608] does not provide
confidentiality, but does provide an authentication mechanism for UAs
to assure that service advertisements only come from trusted SAs with
the exception that it does not provide a mechanism to authenticate
"zero-result responses". See [IPS-SEC] for a discussion of the SLPv2
[RFC2608] security model.
Once an FCIP Entity is discovered, authentication and authorization
are handled by the FCIP protocol. It is the responsibility of the
providers of these services to ensure that an inappropriately
advertised or discovered service does not comprimise their security.
When no security is used for SLPv2, there is a risk of distribution
of false discovery information. The primary countermeasure for this
risk is authentication. When this risk is a significant concern,
IPsec SAs SHOULD be used for FCIP traffic subject to this risk to
ensure that FCIP traffic only flows between endpoints that have
participated in IKE authentication. For example, if an attacker
distributes discovery information falsely claiming that it is an FCIP
endpoint, it will lack the secret information necessary to
successfully complete IKE authentication, and hence will be prevented
from falsely sending or receiving FCIP traffic.
There remains a risk of a denial of service attack based on repeated
use of false discovery information that will cause initiation of IKE
negotiation. The countermeasures for this are administrative
configuration of each FCIP Entity to limit the peers that it is
willing to communicate with (i.e., by IP address range and/or DNS
domain), and maintenance of a negative authentication cache to avoid
repeatedly contacting an FCIP Entity that fails to authenticate.
These three measures (i.e., IP address range limits, DNS domain
limits, negative authentication cache) MUST be implemented.
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6.1. Security Implementation
Security for SLPv2 in an IP storage environment is specified in [IPS-
SEC].
IPsec SHOULD be implemented for SLPv2 as specified in [IPS-SEC]. This
includes ESP with a non-null transform to provide both authentication
and confidentiality.
SLPv2 authentication is OPTIONAL to implement and use, and SLPv2
authentication SHOULD be implemented when IPsec is not supported.
7. IANA Considerations
After RFC publication, an SLP designated expert will oversee
registration of the template(s) in the IANA repository.
8. Internationalization Considerations
SLP allows internationalized strings to be registered and retrieved.
Attributes in the template that are not marked with an 'L' (literal)
will be registered in a localized manner. An "en" (English)
localization MUST be registered, and others MAY be registered.
9. Summary
This document describes how SLPv2 can be used by FCIP Entities to
find other FCIP Entities. Service type templates for FCIP Entities
are presented.
10. Acknowledgements
This draft was produced by the FCIP discovery team, including Todd
Sperry (Adaptec), Larry Lamars (SanValley), Robert Snively (Brocade),
Ravi Natarajan (Lightsand), Anil Rijhsinghani (McData), and Venkat
Rangan (Rhapsody Networks). Thanks also to Mark Bakke (Cisco) for
initial help and consultation, and David Black, Erik Guttman, and
James Kempf for assistance during expert review.
11. Normative References
The references in this section were current at the time this
specification was approved. This specification is intended to operate
with newer versions of the referenced documents. Looking for newer
references is recommended.
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[RFC2608] E. Guttman, C. Perkins, J. Veizades, M. Day. "Service
Location Protocol, version 2", RFC 2608, July 1999.
[RFC2119] S. Bradner. "Key Words for Use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[FCIP] Rajagopal, et. al. "FCIP", draft-ietf-ips-
fcovertcpip-12.txt, February 2003.
[FC-SW-2] Fibre Channel Switch Fabric - 2, ANSI INCITS.355:2001,
December 12, 2001.
[FC-BB-2] Fibre Channel Backbone - 2, T11 Project 1238-D, Rev 6.0,
February 4, 2003.
[FC-FS] Fibre Channel Framing and Signaling, T11 Project 1331-D, Rev
1.90, April 9, 2003.
[IPS-SEC] B. Aboba, et. al. "Securing Block Storage Protocols over
IP", draft-ietf-ips-security-19.txt, January 14, 2003.
12. Informative References
The references in this section may further assist the reader.
[RFC2609] E. Guttman, C. Perkins, J. Kempf. "Service Templates and
service: Schemes", RFC 2609, July 1999.
[RFC2614] J. Kempf, E. Guttman. "An API for Service Location", RFC
2614, June 1999.
[2614BIS] J. Kempf, E. Guttman. "An API for Service Location", draft-
kempf-srvloc-rfc2614bis-00.txt, February 2001.
[RFC3082] J. Kempf, J Goldschmidt. "Notification and Subscription for
SLP", RFC 3082, March 2001.
[RFC3105] Kempf, J., Montenegro, G. "Finding an RSIP Server with SLP",
RFC 3105, October 2001.
[FCIP-MIB] Rijhsinghani, et. al. "FCIP MIB", draft-ietf-ips-fcip-
mib-05.txt, December 2003.
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Author's Address:
David Peterson
SBS Technologies, Inc.
1284 Corporate Center Dr.
St. Paul, MN
USA 55121
Voice: +1 651-905-4755
E-Mail: dap@sbs.com
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