Active SNMP

1
Active SNMP

• S. Keshav
• Cornell University
• (joint work with R. Sharma and M. Wu)
• OPENSIG Workshop
• October 6, 1997

2
Why do we need ambassadors?

• Telecom revolution
• Jets

3
Ambassadors

• Keep track of local news
• Can react quickly to local events
• Summarize and report relevant information
• Can be field-upgraded

4
Ambassadors and agents

• Ambassadors
• Keep track of local news
• Can react quickly to local events
• Summarize and report relevant information
• Can be field-upgraded

• Agents
• Keep track of local routes and multicast
  information
• no horizon effect
• Can react quickly to local changes in network
  state
• Summarize and report relevant information
• Can be upgraded to provide extensible service

5
Active network

• Allows computation, in the form of agents, within
  a network
• Network can actively manipulate data
• filter
• video layers
• firewall
• transform
• compress
• redirect
• mobility

6
Two approaches

• Active packets
• network elements provide runtime environment
• extreme
• Agents in control path
• act on passive packets
• more likely to succeed
• already exists in a rudimentary form (scheduling)

7
Top-level issues

• What are agents allowed to do?
• How do we communicate with them?
• How do we work with existing infrastructure?

8
What are agents allowed to do?

• Effectiveness of an agent depends on
• operations it is allowed to perform (execution
  model)
• data it is allowed to see (data model)
• Data model execution model execution
  environment
• Tradeoff between richness of environment,
  computation cost, and security

9
How to communicate with them?

• Isomorphic to the problem of establishing state
  within networks
• State is currently established by
• signaling
• routing
• network management
• Two options
• use existing protocols for installing state
• new protocol

10
How to be backward compatible?

• Subvert an existing protocol
• Choices
• RSVP
• OSPF/BGP/RIP
• SNMP

11
SNMP Pros and Cons

• Cons
• clunky (ASN.1, no scoping)
• poor security model (communities)
• Pros
• widely available
• simple
• extensible
• well-understood

12
Active SNMP

• Execution model Java runtime
• Data model MIB
• exposed as a Java class
• Snaplets monitor and manipulate MIBs

13
Where do snaplets run?

• On the managed object
• requires JRE in every managed object
• not backward compatible
• On a proxy close to managed object
• not quite perfect, but works

14
Architecture
15
Naming and parameter passing

• Snaplet is embeded in WWW namespace
• http//snmp.cs.cornell.edu/snaplets/icmp_monitor/1
  /1.0/2/2.45
• Snaplet instance is embedded in the MIB
• csgate1.cs.cornell.edu1.3.2.5.6.2.6.1

16
Some applications

• Real time control
• Fine-grained measurement
• Sophisticated trap generation algorithms
• Semantic routing
• find a path with the most RSVP-compliant routers
  between a source and a destination.

17
Discussion

• Active networks are not a panacea
• Add complexity, security holes, and overhead
• But can do some things otherwise impossible
• Active SNMP is a pragmatic first step
• Implementation is up and running at Cornell