One document matched: draft-haas-forces-mib-00.txt
ForCES
Internet Draft R. Haas
Document: draft-haas-forces-mib-00.txt IBM
Expires: April 18, 2006 October 2005
ForCES MIB
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ForCES MIB October 15, 2005
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Abstract
This memo defines a Management Information Base (MIB) for use with
network management protocols in the Internet community. In
particular, it defines a MIB for the Forwarding and Control Element
Separation (ForCES) Network Element (NE). The ForCES working group
is defining a protocol to allow a Control Element (CE) to control the
behavior of a Forwarding Element (FE).
Conventions used in this document
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 [RFC2119]i.
Table of Contents
1. Introduction...................................................2
2. Design of ForCES MIB...........................................4
3. Capturing State Before Association Establishment...............4
4. MIB Definition(s)..............................................5
Security Considerations...........................................5
References........................................................6
Acknowledgments...................................................6
Author's Addresses................................................6
1.
Introduction
The ForCES MIB is a read-only MIB that captures information related
to the ForCES protocol. This includes state information about the
associations between CE(s) and FE(s) in the NE.
The ForCES MIB does not include information that is specified in
other MIBs, such as packet counters for interfaces, etc.
The information in the ForCES MIB relative to associations includes
more specifically:
- identifiers of the elements in the association
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ForCES MIB October 15, 2005
- state of the association
- configuration parameters of the association
- statistics of the association
The relevant references from the ForCES requirements and architecture
documents are repeated below:
From the ForCES requirements RFC [RFC 3654], Section 4, point 4:
“A NE MUST support the appearance of a single functional device.
For example, in a router, the TTL of the packet should be
decremented only once as it traverses the NE regardless of how many
FEs through which it passes. However, external entities (e.g., FE
managers and CE managers) MAY have direct access to individual
ForCES protocol elements for providing information to transition
them from the pre-association to post-association phase.”
And [RFC 3654], Section 4, point 14:
“1. The ability for a management tool (e.g., SNMP) to be used to
read(but not change) the state of FE SHOULD NOT be precluded.
2. It MUST NOT be possible for management tools (e.g., SNMP, etc)
to change the state of a FE in a manner that affects overall NE
behavior without the CE being notified.”
According to the ForCES architecture RFC [RFC 3746], Section 3.3:
“CE managers may be physically and logically separate entities that
configure the CE with FE information via such mechanisms as COPS-PR
[7] or SNMP [5].”
and [RFC 3746], Section 5.7:
“RFC 1812 [2] also dictates that "Routers MUST be manageable by
SNMP". In general, for the post-association phase, most external
management tasks (including SNMP) should be done through
interaction with the CE in order to support the appearance of a
single functional device. Therefore, it is recommended that an SNMP
agent be implemented by CEs and that the SNMP messages received by
FEs be redirected to their CEs. AgentX framework defined in RFC
2741 ([6]) may be applied here such that CEs act in the role of
master agent to process SNMP protocol messages while FEs act in the
role of subagent to provide access to the MIB objects residing on
FEs. AgentX protocol messages between the master agent (CE) and
the subagent (FE) are encapsulated and transported via ForCES, just
like data packets from any other application layer protocols.”
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2.
Design of ForCES MIB
As state information is distributed across FEs and CEs, the following
alternatives may be considered:
1) CE MIBs
Each CE in the NE implements a CE MIB. The external SNMP-based
management tool must therefore be aware of each CE in order to obtain
a complete view of the NE by collecting state information obtained
from each CE MIB.
[Note: this may or may not comply with requirement #4 ("A NE MUST
support the appearance of a single functional device")]
2) single NE MIB
An entity in the NE implements an NE MIB that aggregates state
information collected from each CE (CEs are possibly from various
vendors). This requires a standard protocol in order to support
multi-vendor environment. AgentX with the NE as the master and the
CE(s) as the agent(s) may be considered here.
[Note: comments on the suitability of AgentX]
[Note: must choose between the two alternatives]
3.
Capturing State Before Association Establishment
The ForCES protocol may be used by the CE to query the FE Protocol
LFB about some of the configuration parameters. But such queries may
obviously be issued only once the association is established.
In the ForCES protocol, the FE first issues an Association Setup
Request message to the CE which in turns responds with an Association
Setup Response message. It may be useful to capture in the MIB in
which state the association is seen from each of the FE and the CE
sides, as a means to detect PL-level communication anomalies. For
instance, from the FE side, the association is in the ATTEMPT state
as long as no response to the Association Setup message has been
received from the CE. Similarly, the association is in the
ESTABLISHING state as long as no message has been received from the
FE after the CE has issued a positive Association Setup Response
message (this is because configuration mistakes in the FE may cause
messages from the CE to be ignored, and the MIB could help in tracing
such errors).
The transient state in the FE until the association is established
cannot be queried using ForCES.
[Note: If such information is critical, then an FE MIB has to be
provided that can be queried separately]
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4.
MIB Definition(s)
For each association identified by the pair CE ID and FE ID, the
following information is included in the MIB:
[Note: the MIB includes all associations for the particular CE in the
case of a CE MIB, same for FE MIBs (if any), or all associations in
the NE in the case of a NE MIB]
- Current state of the association:
UP: the CE(s) indicated by the CE ID and FE(s) indicated by
the FE ID are associated.
ESTABLISHING/ATTEMPT: transient state unitl the association is
established. See section 3 above for details.
Note that associations that are not UP and for which no association
setup is in progress are NOT listed in the MIB.
[Note: otherwise how do we decide which old associations to remove
from the MIB ?]
- Hearbeat timers values of the FE and CE for this association.
- Heartbeat timer settings of the FE and CE for this association:
ENABLED: hearbeats are transmitted (by default virtual piggybacking
is used)
DISABLED: heartbeats are not transmitted
- Backup information: the FE(s)/CE(s) that are configured to work as
backups for this association.
[Note: is this necessary, useful ?]
- Association statistics:
Date/time when the association came to the UP state.
[Note: what about the Number of commands executed or some indications
of the ForCES control traffic ?]
[Note: add actual MIB specification]
Security Considerations
Some of the readable objects in this MIB module may be considered
sensitive or vulnerable in some network environment.
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[Note: expand on this if necessary]
SNMP versions prior to SNMPv3 did not include adequate security.
Even if the network itself is secure (for example by using IPSec),
even then, there is no control as to who on the secure network is
allowed to access and GET/SET (read/change/create/delete) the objects
in this MIB module.
It is RECOMMENDED that implementers consider the security features as
provided by the SNMPv3 framework (see [RFC3410], section 8),
including full support for the SNMPv3 cryptographic mechanisms (for
authentication and privacy).
Further, deployment of SNMP versions prior to SNMPv3 is NOT
RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to
enable cryptographic security. It is then a customer/operator
responsibility to ensure that the SNMP entity giving access to an
instance of this MIB module is properly configured to give access to
the objects only to those principals (users) that have legitimate
rights to indeed GET or SET (change/create/delete) them.
References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3654] Khosravi, H,, and Anderson, T., “Requirements for
Separation of IP Control and Forwarding”, RFC 3654, November 2003.
[RFC3746] Yang, L., Dantu, R., Anderson, T., Gopal, R., “Forwarding
and Control Element Separation (ForCES) Framework”, RFC 3746, April
2004.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet- Standard
Management Framework", RFC 3410, December 2002.
Acknowledgments
Author's Addresses
Robert Haas
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ForCES MIB October 15, 2005
IBM Research
Zurich Research Lab
Saeumerstrasse 4
8803 Rueschlikon
Switzerland
Email: rha@zurich.ibm.com
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