Notes

Outline

Bi-Level Active Networks Jon Crowcroft Hermann De Meer Ken Carlberg

Background: IP IP architecture built on Layered Model Some current efforts bend/break the model Congestion avoidance: RED Division of resources: CBQ, WFQ QoS: diff-serv, int-serv

Background: Active Networks Add functionality/services “on the fly” Initially, Active Router (AR) ‘Reprogram’ code in data packets Active Server (AS) Dynamically loaded software modules  Used as proxies for additional services offered by the network Transcoding Dynamic VPNs

Active Net Issues Security Need to prevent adverse functions Approaches include strict semantics (SecuNet), polices (Android/FAIN), and ‘sandboxes’ (execution environments) Performance ‘Slow path’ for option-filled data packets in routers Lack of inter-layer information leads to… Redundant functions between layers (e.g., Application layer routing/discovery) Sub-optimal performance of end-to-end flows

Objectives Retain the layered model Break it for ‘active’ flows Focus solution on integrated operation between AR and AS

Bi-Level Architecture Network consisting of AR and AS Similar to ALAN architecture AS and AR communicate/compliment each other Language between AR and AS Articulate type, form, target Expansion of Secunet language(?) and/or XML-programable router project(??) Policies

Architecture Example

Bi-Level Usage Example Active Flow through AS-A and AS-B AS-A determines that flow is subject ‘active’ service AS-A triggers AR to send constrained flood Determine new paths with different metrics Constrain advertisement to shaded region using ‘active’ routing protocol Note: Example represents gradual active service

Another Example NATs and Firewalls Nat’s operate like a primative network AN device Firewalls act like an application layer (possibly) Need to coordinate (e.g. the tweaking/open door protocol) between the two

Reflection on Action, Action on Reflection Reflection is a neat tool for distributed systems middleware C.f. work at lancaster and irvine on reflection for mobile and multimedia Seems ideal for Bi-Level architecture too!

Summary/Conclusions Good reasons for 2 levels of overlay Can achieve 3 or more just by recursing, so no need for n-layer model, unlike ISO Need to work on the meta-object protocol in the real sense of the word protocol so that two layers can comprehend each others internal behaviours.