Network Working Group H. Mukhtar Ed.
Internet-Draft S. Joo
Intended status: Informational ETRI
Expires: April 24, 2010 J. Schoenwaelder
Jacobs University Bremen
K. Kim
Ajou University
October 21, 2009
SNMP optimizations for 6LoWPAN
draft-hamid-6lowpan-snmp-optimizations-02.txt
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Abstract
Simple Network Management Protocol (SNMP) is a widely deployed
application protocol for network management and data retrieval. In
this document we describe the applicability of SNMP for 6LoWPANs. We
discuss the implementation considerations of SNMP Agent and SNMP
Manager followed by the deployment considerations of the SNMP
protocol. Our discussion also covers the applicability of MIB
modules for 6LoWPAN devices.
Requirements Language
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].
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Why SNMP . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Little-known SNMP Features . . . . . . . . . . . . . . . . . . 5
2.1. SNMP Contexts . . . . . . . . . . . . . . . . . . . . . . 5
2.2. SNMP Proxies . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Message Size Restrictions . . . . . . . . . . . . . . . . 5
3. SNMP Agent Implementation Considerations . . . . . . . . . . . 6
3.1. Access Control . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Overhead of the Different SNMP Message Formats . . . . . . 6
3.2.1. Overhead Difference of SNMPv3 Security . . . . . . . . 6
3.2.2. Minimum Message Size Calculation . . . . . . . . . . . 7
4. SNMP Manager Implementation Considerations . . . . . . . . . . 7
4.1. Polling, Pushing, and Trap-directed Polling . . . . . . . 8
4.2. Support for SNMP Proxies . . . . . . . . . . . . . . . . . 8
5. SNMP Deployment Considerations . . . . . . . . . . . . . . . . 8
5.1. Naming Issues . . . . . . . . . . . . . . . . . . . . . . 9
5.2. SNMP Protocol Operations . . . . . . . . . . . . . . . . . 9
5.3. Timeouts and Retransmissions . . . . . . . . . . . . . . . 9
5.4. Polling Intervals . . . . . . . . . . . . . . . . . . . . 9
5.5. Caching Issues . . . . . . . . . . . . . . . . . . . . . . 10
6. Applicable MIB Modules . . . . . . . . . . . . . . . . . . . . 10
6.1. Applicable Standardized MIBs . . . . . . . . . . . . . . . 10
6.2. MIB Design Guidelines for Low Overhead . . . . . . . . . . 10
7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 10
9. Security Considerations . . . . . . . . . . . . . . . . . . . 10
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative References . . . . . . . . . . . . . . . . . . . 11
11.2. Informative References . . . . . . . . . . . . . . . . . . 12
Appendix A. Calculation of Minimum packet size . . . . . . . . . 13
Appendix B. Possible Deployment Models for SNMP . . . . . . . . . 15
B.1. Lightweight End-to-End . . . . . . . . . . . . . . . . . . 15
B.2. Proxy Model . . . . . . . . . . . . . . . . . . . . . . . 15
B.3. SNMP with Sub-Agent Protocols . . . . . . . . . . . . . . 16
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
Simple Network Management Protocol (SNMP) is a UDP-based protocol
operating in the application layer of the Internet Protocol Suite.
It consists of four basic components: a managed node running an
agent; an entity running management applications (typically called as
a manager); a protocol to convey information between the SNMP
entities; and management information.
1.1. Why SNMP
SNMP is datagram-oriented and the implementations of SNMP can be very
lightweight. It may fit 6LoWPAN applications very well. The
following features make SNMP suitable for this network.
- Protocol Maturity: SNMPv3 is a full IETF standard having a high
degree of technical maturity with significant experiences in
implementation and operation.
- Data Naming: SNMP provides a hierarchical namespace utilizing
object identifiers (OIDs) for data naming purposes. The data
accessible via SNMP is described by Management Information Bases (MIB
modules). These MIB modules can either be standardized or specific
to certain enterprises.
- Network Management: According to [RFC4919] network management is
one of the goals for 6LoWPANs, wherein it is described that network
management functionality is critical for 6LoWPANs. SNMP is widely
used for network management and it is the Internet community's de
facto management protocol.
- Data Retrieval: SNMP employs polling in which data is being
requested by a manager from the agents. In addition, SNMP supports a
push model in which data is sent from agents to the managers without
a prior request. Trap-directed polling refers to a mode where
polling is used with relatively long polling intervals but agents can
send notifications in order to notify a manager of events that might
require changes to the polling strategy.
- Security: SNMPv3 can provide both message-level and transport-level
security. SNMPv3 defines User based Security model (USM) for
message-driven security; and transport-based security model (TSM) for
transport-driven security. TSM makes it possible to use existing
security protocols such as Transport Layer Security (TLS) [RFC5246]
and the Datagram Transport Layer Security (DTLS) Protocol [RFC4347]
with SNMPv3. The modular design of SNMPv3 also allows new security
and access control protocols to be added to it.
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- Access control: SNMP can provide access control of the information.
2. Little-known SNMP Features
This section explains some little-known SNMP concepts.
2.1. SNMP Contexts
Each SNMP entity is composed of a single engine which is identified
by an SNMP engine identifier. A context is a collection of
management information accessible by an SNMP entity and it is also
defined as a subset of a single SNMP entity. An SNMP entity has
access to one or more contexts uniquely identified by context names.
In order to identify an individual item of management information
within the management domain, the SNMP entity's context is identified
first (using the engine identifier and context name) and this is
followed by the object type and instance.
2.2. SNMP Proxies
The term 'proxy' in SNMP has a restrictive meaning. A proxy refers
to a proxy forwarder application which forwards SNMP messages to
other SNMP engines and forwards the response to such previously
forwarded messages back to SNMP engine from which the original
message was received [RFC3413]. The forwarding is based on contexts
and it is irrespective of the management objects being accessed.
Thus, an SNMP proxy can be used to forward messages from one
transport to another, or to translate SNMP messages from one version
to another version.
The SNMP proxy cannot be used for translation of SNMP requests into
operations of a non-SNMP management protocol and it cannot be used
for supporting aggregated objects. Proxies depend on context
information and the forwarding of messages is independent of the
objects being accessed. To support aggregated objects, where the
value of one object depends upon multiple other remote items, special
MIB modules and sub-agent protocols are used instead of proxies.
2.3. Message Size Restrictions
SNMP message contains a msgMaxSize field which is used to communicate
the maximum message size at the sender and the receiver side. The
maximum message size is the maximum size of a message that can be
accepted by the receiving entity.
The minimum required to implement message size is transport model
specific. For SNMP over UDP, the size is 484 octets.
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3. SNMP Agent Implementation Considerations
This section covers SNMP agent implementation considerations for
6LoWPAN.
3.1. Access Control
The Local Configuration Datastore (LCD), which contains access rights
and policies of an SNMP entity, need not be configured remotely. It
is recommended to have permanent access control tables on the nodes.
The implementers should keep the authorization tables as compact as
possible to reduce the memory and codesize overhead. Compact
permanent authorization tables on the nodes can for example provide
read-only and read-write access to the management instrumentation on
the node at almost zero processing cost since the SNMP agents may not
support instance level access control granularity to further reduce
performance cost.
3.2. Overhead of the Different SNMP Message Formats
SNMPv1 [RFC1157] is the earliest version of SNMP and it reached the
IETF full standard status. The protocol operation consisted of Get,
Get-Next, and Trap Operations for data retrieval and the Set
operation for configuration. SNMPv1 security is based on community
string based authentication. Access control is provided with SNMP
MIB views. SNMPv2c was an experimental improvement over SNMPv1 which
introduced new data retrieval operations, i.e., Get-Bulk and Inform,
and introduced improved error handling. SNMPv2c could only reach the
experimental status.
SNMPv3, Std 62 [RFC3411]-[RFC3418], supports all the aforementioned
data retrieval and configuration options of SNMPv1 and SNMPv2c. The
SNMPv3 framework is modular in order to enhance extensibility.
Moreover, SNMPv3 supports authentication and data integrity and an
additional privacy option for confidentiality. After SNMPv3 became a
full standard, SNMPv1 and SNMPv2c were declared Historic due to their
weak security features. However, SNMPv3 can coexist with the earlier
versions of SNMP [RFC3584].
3.2.1. Overhead Difference of SNMPv3 Security
SNMP security can be supported by two different approaches, i.e.,
message-driven security and transport-driven security. With message-
driven security (the User-based Security Model, USM), SNMP provides
its own security where the security parameters are passed within each
SNMP message. On the other hand, transport-driven security enables
operators to leverage existing secure transport protocols (e.g., the
Transport Security Model, TSM).
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The User-based Security Model [RFC3414] is a shared secret scheme
which uses message-driven security. Although it utilizes existing
mechanisms, it is designed independent of other security
infrastructures. It provides its own security and has its own key
management infrastructure. The operator configures secrets in the
SNMP engines used by management applications. These independent
authentication and encryption keys are used to secure communication.
Messages can be authenticated, or authenticated and encrypted.
The Transport Security Model (TSM) enables operators to leverage
existing security infrastructures and secure transport protocols.
TSM allows security to be provided by an external secure transport
protocol. TSM enables the use of existing security mechanisms, such
as Transport Layer Security (TLS) [RFC5246], Datagram Transport Layer
Security (DTLS) Protocol [RFC4347], and the Secure Shell (SSH)
Protocol [RFC4251].
In transport-driven protocols DTLS, which is UDP based, can be
considered for 6LoWPAN. [I-D.draft-ietf-isms-dtls-tm] specifies how
DTLS can be used with SNMP. Transport Model for DTLS protocol
involves an initial handshake to establish a session. Upon
successful session establishment, the security related session
parameters are cached in the client and the server for the duration
of the session instead of being sent in all messages. The session is
based on UDP source and destination address/port pairs. Therefore
for session de-multiplexing a different UDP source port is selected
for every new session to distinguish between multiple sessions from a
source to same port on the destination.
3.2.2. Minimum Message Size Calculation
The minimum message size for SNMPv3 with USM is 67 bytes whereas the
minimum message size for SNMPv3 with TSM is 46 bytes. The minimum
message size for the historic SNMPv1 message is 20 byte. The details
of the calculation can be found in Appendix A. TSM may involve
additional session establishment cost consisting of the initial
handshake and the caching of transport parameters. The tradeoff
between the message size and session overhead should be kept in mind
while designing applications.
4. SNMP Manager Implementation Considerations
This section covers SNMP manager implementation considerations for
6LoWPAN.
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4.1. Polling, Pushing, and Trap-directed Polling
In Sensor networks, polling can be reactive or proactive. Data
gathering or event reporting sensors may 'push' their information
towards the managers or they may wait for a manager to 'pull' the
information through a request.
When the demand for data is relatively high, push mechanisms are
deployed in order to save energy cost where the data flows from
managed entities towards the managers. SNMP notifications are a
realization the push based model in which data is sent to the manager
without a prior request. Data can be reported periodically from the
SNMP agent to the manager through SNMP notifications and the
notifications can take the advantage of SNMP security and access
control features to ensure the access to legitimate users along with
confidentiality and integrity of the data. The SNMP Inform PDU
requires a response back from the receiving manager and it can be
used in applications in which reliability is important.
The use of notifications is recommended for data flows from sensors
to the manager and also for the scenarios where multiple nodes
generate the same information.
4.2. Support for SNMP Proxies
The SNMP proxy forwarder application resides on an intermediate SNMP
entity (e.g. an SNMP entity on a management server or an edge router
in case of 6LoWPAN). The proxy forwarder registers each context to
which it wishes to forward messages. After the remote context is
registered, the managers send messages to the proxy forwarder's
engine with the context information of the remote host. The proxy
forwarder forwards the message to the remote context. Upon reception
of a response from the remote host, it forwards the response back to
the manager.
In 6LoWPAN networks proxies may be used to change message encoding,
or they may be used to translate between SNMP versions, or they may
be used to change the security domain at the 6LoWPAN side of the
network.
5. SNMP Deployment Considerations
Following are a list of considerations for deployment of SNMP in
6LoWPANs.
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5.1. Naming Issues
In order to reduce the message overhead, the managers are advised to
use short values for Engine Identifiers. The minimum length for an
Engine Identifier is 5 octets. The managers may generate and assign
the Engine identifiers using the 16-bit short address or the 64-bit
IEEE EUI-64 addresses of a node. Context name is an administratively
assigned octet string that names a context. In order to reduce the
message size overhead the length of the string should be kept short.
The default context is identified by a a zero-length context name.
5.2. SNMP Protocol Operations
SNMP supports four basic data retrieval operations i.e. GetRequest-
PDU, GetNextRequest-PDU, GetBulkRequest-PDU [RFC3416]. The
GetRequest-PDU is useful for retrieving well known scalar data,
whereas the GetNextRequest-PDU and GetBulkRequest-PDU operations are
particularly advantageous for retrieving dynamically changing tabular
data. The SNMPv2-Trap-PDU and InformRequest-PDU can be used for
push-based data retrieval, in which periodic or event-based
notifications are sent to the managers.
During the processing of a GetBulkRequest-PDU operation, the agent
can decide the number of objects to include in response. For
requesting objects the manager has to consider the underlying packet
size constraints. Also, the number of objects in the variable-
binding in request messages and max-repeaters field of GetBulk
operation should be selected keeping the constraint in mind.
5.3. Timeouts and Retransmissions
In 6LoWPANs, the SNMP message may be fragmented or may encounter more
latency because of underlying wireless link. The value of timeouts
should be adjusted on the manager side by considering the link
characteristics so that SNMP does not timeout between queries. In
some cases the number of retries may also be adjusted to cater for
link characteristics.
5.4. Polling Intervals
Similarly, in order to reduce the amount of polling, the polling
interval should be increased for less time critical data. 6LoWPANs
are energy constrained networks and excessive polling is not
recommended.
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5.5. Caching Issues
Caching the important information can save the transmission cost e.g.
caching the snmpEngineID would save the traffic overhead of EngineID
discovery mechanisms. It is recommended that the EngineID should be
cached in order to reduce the transmission cost. In case of TSM,
caching the transport parameters can reduce the message sizes.
6. Applicable MIB Modules
This section describes some relevant MIB modules which can be used in
6LoWPAN.
6.1. Applicable Standardized MIBs
ENTITY-SENSOR-MIB [RFC3433] defines objects for information that is
associated with physical sensors (e.g. the current value of the
sensor, operational status, and the data units precision associated
with the sensor). It can be reused for 6LoWPANs. Other applicable
MIB modules are TBD.
6.2. MIB Design Guidelines for Low Overhead
When defining MIB modules, the MIB designers should avoid using long
OIDs by avoiding unnecessary data hierarchies. Moreover, complex
indexing schemes should be avoided in order to keep the overhead
resulting from instance identifiers as low as possible.
7. Conclusion
SNMP can be very useful for 6LoWPANs due to its significant
implementation and operational experiences. The standards allow for
memory and CPU efficient implementations. The utilization of secure
transports such as DTLS can reduce the overhead of message-based
security mechanisms. This document explored the applicability of
SNMP for its use in 6LoWPAN.
8. IANA Consideration
TBD.
9. Security Considerations
TBD.
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10. Acknowledgments
TBD.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in
RFCs to Indicate Requirement Levels",
BCP 14, RFC 2119, March 1997.
[RFC3411] Harrington, D., Presuhn, R., and B.
Wijnen, "An Architecture for
Describing Simple Network Management
Protocol (SNMP) Management
Frameworks", STD 62, RFC 3411,
December 2002.
[RFC3412] Case, J., Harrington, D., Presuhn, R.,
and B. Wijnen, "Message Processing and
Dispatching for the Simple Network
Management Protocol (SNMP)", STD 62,
RFC 3412, December 2002.
[RFC3413] Levi, D., Meyer, P., and B. Stewart,
"Simple Network Management Protocol
(SNMP) Applications", STD 62,
RFC 3413, December 2002.
[RFC3414] Blumenthal, U. and B. Wijnen, "User-
based Security Model (USM) for version
3 of the Simple Network Management
Protocol (SNMPv3)", STD 62, RFC 3414,
December 2002.
[RFC3415] Wijnen, B., Presuhn, R., and K.
McCloghrie, "View-based Access Control
Model (VACM) for the Simple Network
Management Protocol (SNMP)", STD 62,
RFC 3415, December 2002.
[RFC3416] Presuhn, R., "Version 2 of the
Protocol Operations for the Simple
Network Management Protocol (SNMP)",
STD 62, RFC 3416, December 2002.
[RFC3417] Presuhn, R., "Transport Mappings for
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the Simple Network Management Protocol
(SNMP)", STD 62, RFC 3417,
December 2002.
[RFC3418] Presuhn, R., "Management Information
Base (MIB) for the Simple Network
Management Protocol (SNMP)", STD 62,
RFC 3418, December 2002.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui,
J., and D. Culler, "Transmission of
IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, September 2007.
[RFC5590] Harrington, D. and J. Schoenwaelder,
"Transport Subsystem for the Simple
Network Management Protocol (SNMP)",
RFC 5590, June 2009.
[RFC5591] Harrington, D. and W. Hardaker,
"Transport Security Model for the
Simple Network Management Protocol
(SNMP)", RFC 5591, June 2009.
[RFC3433] Bierman, A., Romascanu, D., and K.
Norseth, "Entity Sensor Management
Information Base", RFC 3433,
December 2002.
[RFC1157] Case, J., Fedor, M., Schoffstall, M.,
and J. Davin, "Simple Network
Management Protocol (SNMP)", STD 15,
RFC 1157, May 1990.
[I-D.draft-ietf-isms-dtls-tm] Hardaker, W., "Transport Layer
Security Transport Model for SNMP",
September 2009.
11.2. Informative References
[RFC3410] Case, J., Mundy, R., Partain, D., and
B. Stewart, "Introduction and
Applicability Statements for Internet-
Standard Management Framework",
RFC 3410, December 2002.
[RFC2741] Daniele, M., Wijnen, B., Ellison, M.,
and D. Francisco, "Agent Extensibility
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(AgentX) Protocol Version 1",
RFC 2741, January 2000.
[RFC3584] Frye, R., Levi, D., Routhier, S., and
B. Wijnen, "Coexistence between
Version 1, Version 2, and Version 3 of
the Internet-standard Network
Management Framework", BCP 74,
RFC 3584, August 2003.
[RFC4919] Kushalnagar, N., Montenegro, G., and
C. Schumacher, "IPv6 over Low-Power
Wireless Personal Area Networks
(6LoWPANs): Overview, Assumptions,
Problem Statement, and Goals",
RFC 4919, August 2007.
[RFC5246] Dierks, T. and E. Rescorla, "The
Transport Layer Security (TLS)
Protocol Version 1.2", RFC 5246,
August 2008.
[RFC4347] Rescorla, E. and N. Modadugu,
"Datagram Transport Layer Security",
RFC 4347, April 2006.
[RFC4251] Ylonen, T. and C. Lonvick, "The Secure
Shell (SSH) Protocol Architecture",
RFC 4251, January 2006.
[RFC4789] Schoenwaelder, J. and T. Jeffree,
"Simple Network Management Protocol
(SNMP) over IEEE 802 Networks",
RFC 4789, November 2006.
Appendix A. Calculation of Minimum packet size
A very rough way to estimate the size needed by a varbind that is
essentially a number is the following formula:
varbind-size = 6 + number-of-OID-subidentifier
That is for sysUpTime (1.3.6.1.2.1.1.3), we get 14 bytes and thus the
SNMPv1 message is 34 bytes, SNMPv3/TSM is 60 bytes, and the SNMPv3/
USM message is 81 bytes. TSM may imply security overhead at the
transport layer e.g. in case of DTLS the transport layer framing
overhead is 13 bytes (compressed DTLS may further reduce the
application payload length). The details of the calculation in
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section 3.2.2 are as follows:
* SNMPv3 minimum message size calculation
SNMPv3Message (USM) 2 byte
msgVersion 3 byte
msgGlobalData (HeaderData) 15 byte
msgSecurityParameters 23 byte
msgData (ScopedPDU) 24 byte
-------
67 byte
SNMPv3Message (TSM) 2 byte
msgVersion 3 byte
msgGlobalData (HeaderData) 15 byte
msgSecurityParameters 2 byte
msgData (ScopedPDU) 24 byte
-------
46 byte
UsmSecurityParameters 2 byte
msgAuthoritativeEngineID 7 byte
msgAuthoritativeEngineBoots 3 byte
msgAuthoritativeEngineTime 3 byte
msgUserName 2 byte
msgAuthenticationParameters 2 byte
msgPrivacyParameters 2 byte
-------
21 byte
TsmSecurityParameters 2 byte
-------
2 byte
HeaderData 2 byte
msgID 3 byte
msgMaxSize 4 byte
msgFlags 3 byte
msgSecurityModel 3 byte
-------
15 byte
ScopedPDU 2 byte
contextEngineID 7 byte
contextName 2 byte
PDU 13 byte
-------
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24 byte
PDU 2 byte
request-id 3 byte
error-status 3 byte
error-index 3 byte
variable-bindings 2 byte
-------
13 byte
* SNMPv1 / SNMPv2c minimum mesage size calculation
SNMPv1Message 2 byte
version 3 byte
community 2 byte
data (PDU) 13 byte
-------
20 byte
The details of the calculation for DTLS framing as follows:
Type 1 byte
Version 2 byte
Epoch 2 byte
Sequence_number 6 byte
Length 2 byte
Appendix B. Possible Deployment Models for SNMP
There can be three fundamental deployment models for SNMPv3
B.1. Lightweight End-to-End
The SNMP manager talks SNMPv3 end-to-end to the nodes. In this way
existing management tools can be reused and a few adaptations may be
needed by specifying suitable deployment parameters through an
Applicability Statement as covered by this draft.
Manager <-------------------------------------> 6LoWPAN nodes
SNMPv3
B.2. Proxy Model
The SNMP manager talks SNMPv3 to an SNMP proxy residing on the
6LoWPAN Gateway (or a proxy server) as explained in this document.
Existing management tools (as long as they are proxy aware, which is
not generally true) can be reused.
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Manager <--------> SNMP Proxy <--------------> 6LoWPAN nodes
SNMPv3 (6LoWPAN ER) SNMPv3
B.3. SNMP with Sub-Agent Protocols
The SNMP manager talks SNMPv3 to an extensible SNMP agent residing on
the 6LoWPAN router which uses a subagent protocol (e.g. a 6LoWPAN
enhanced version of AgentX, [RFC2741]) to populate its MIB. However,
the current standard subagent protocol is not suitable for 6LoWPAN
since it assumes a reliable stream-oriented transport and an
adaptation of an existing protocol may be required. Thus, this model
is not recommended for 6LoWPANs.
Manager <-------> SNMP Agent <-----------------> 6LoWPAN nodes
SNMPv3 (6LoWPAN ER) SubAgent Protocol
Appendix C. Change Log
Changes from -01 to -02:
The draft now covers applicability of SNMPv3 for 6LoWPANs. The focus
of the draft is shifted towards supporting SNMPv3 'as is' in
6LoWPANs.
1. Added SNMP Agent Implentation Considerations for 6LoWPANs.
2. Added SNMP Manager Implentation Considerations for 6LoWPANs.
3. Added the Deployment Considerations for 6LoWPANs.
4. Added the Applicable MIB modules for 6LoWPANs.
5. Moved SNMP Deployment Models to Appendix.
6. Removed the section on Packet Compression.
Authors' Addresses
Hamid Mukhtar (editor)
ETRI
USN Research Division, ETRI, 161 Gajeong-dong, Yuseong-gu,
Daejeon 305-350
KOREA
Phone: +82 42 860 5435
EMail: hamid@etri.re.kr
Mukhtar Ed., et al. Expires April 24, 2010 [Page 16]
Internet-Draft SNMP optimizations for 6LoWPAN October 2009
Seong-Soon Joo
ETRI
USN Research Division, ETRI, 161 Gajeong-dong, Yuseong-gu,
Daejeon 305-350
KOREA
Phone: +82 42 860 6333
EMail: ssjoo@etri.re.kr
Juergen Schoenwaelder
Jacobs University Bremen
Campus Ring 1
Bremen 28725
Germany
Phone: +49 421 200-3587
EMail: j.schoenwaelder@jacobs-university.de
Kim, Ki Hyung
Ajou University
San 5 Wonchun-dong, Yeongtong-gu
Suwon-si, Gyeonggi-do 442-749
KOREA
Phone: +82 31 219 2433
EMail: kkim86@ajou.ac.kr
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