Introduction to the Simple Network Management Protocol SNMP

1
Introduction to the Simple Network Management
Protocol (SNMP)

• Ben Voigt
• University of Pennsylvania
• 16 July 2003

2
Outline

• What is the Simple Network Management Protocol?
• Does APNets need SNMP?

3
What is the Simple Network Management Protocol?

• What does it provide?
• How does it work?
• Why is it important?

4
Knowledge-Plane, 1988-style

• RFC 1067
• Simple interface read/write named parameters,
  notification of parameters exceeding thresholds
• Allows monitoring through reading statistical
  counters maintained by nodes
• Allow management by writing control registers
  thus modifying network behavior
• Traps make event-driven programming possible

5
Features of SNMP

• Simple atomic operations place few restrictions
  on design of management system
• Self-describing data format with descriptive
  schema, like XML (but far more bandwidth-efficient
  )
• Latest version SNMPv3
• adds authentication and privacy to the protocol
• standardizes access control (see next slide)

6
SNMP Data Storage

• Parameters are stored in a hierarchical namespace
• allows multi-valued parameters
• delegation of naming in different branches allows
  concurrent development (.iso.org.dod.internet.priv
  ate.enterprises.)
• management applications may be restricted to
  particular subbranches
• Standard view-based access control is
  decentralized and kludgy, but SNMP allows new
  methods of authentication, privacy, and
  access-control to be added

7
SNMP In Todays Internet

• All enterprise-class, and increasing numbers of
  workgroup networking devices support SNMP
• Enterprise-class devices tend to use SNMP as the
  primary management mechanism, and sell plugins
  for SNMP Managers (HP OpenView, similar offerings
  from IBM, ), facilitating centralized management

8
SNMP In Todays Internet

• Small devices tend to export only the required
  statistical counters, and define a proprietary
  management protocol
• This prevents centralized control, unless all
  devices are purchased from a single vendor (and
  sometimes not even then)

9
Does APNets need SNMP?

• Why should we use it? (Or not?)
• What can we learn from it?
• What can we learn from its documentation?

10
Should we use SNMP?

• Interim Knowledge-Plane substitute
• Pros
• Huge amounts of information on network quality
  already available
• Management infrastructure exists to analyze
  traffic patterns if we export MIBs from our
  hardware/software devices
• Cons
• PITA ASN.1 Notation, clock synchronization

11
Can we learn from SNMP?

• Strengths extensible, extensible, extensible
• Data transfer is (reasonably) efficient
• Principal authentication allows fine-grained
  access control
• Cons User Security Model is flexible and
  powerful, but decentralized updates must be
  propagated to all devices via SNMP

12
How about the documentation?

• SNMPv3 is Highly Extensible and Modularized
• Data Transfer, Authentication, Privacy,
  Encryption, Access Control schemes may be
  independently changed
• Documentation shows a modern design and
  presentation of a modular protocol
• Documentation suggests modular implementation
  which can be easily extended

13
Questions

• Further questions?