Final Report

1
Final Report

• Load Balancing in SIP/VMS
• Wilbur Oh
• willblur_at_cs.tu-berlin.de

2
Overview

• Introduction
• Requirements
• Policy Language
• System Model
• Behavior Definitions
• Conclusions

3
Introduction

• SIP/VMS system records voice messages over IP
  telephony
• Main components are SER, SIP/VMS UA and VMS
• SER is sued to receive SIP calls
• SIP/VMS UA handles the SIP request and also to
  communicate with the VMS
• VMS used to handle the recoding of the message
• Load Balancing required in two areas
• The selection of a SIP/VMS UA
• The selection of a VMS ( if more than one is used)

4
Requirements

• General requirements
• Resource availability must be reliable at SER
  (GEN Agent), if no resource are available caller
  must be notified.
• GEN must not affect AIP and VMS original
  behaviors such as failure notification
• Extra configuration for emergency calls
• Midcom requirements (from Swale et. al.)
• The Midcom protocol must enable the middlebov and
  any associated Midcom agents to establish known
  and stable state
• The middle box should be able to report its
  status to a Midcom agent with which it is
  associated

5
Requirements

• Midcom requirements
• A Midcom must be able to determine whether or not
  a request was successful
• The Midcom protocol must support the ability of
  an agent to install a ruleset that governs
  multiple types of middlebox actions (e.g.
  firewall and NAT)
• Load balancing requirements
• Only one SIP UA can handle only one SIP session
  at any one time
• The distribution of load to a GEN agent should be
  fair and there should not be any hard-wired
  relation between SIP UA and SER
• Selection of SIP UA should be independent on the
  number of entities

6
Policy Language

• Created by Solomon and Lupu
• Policy language approach to program network
  components
• Make the configuration of the components more
  dynamic
• Language is in 2 categories
• Authorization policies controls access policies
  to protect resources from unauthorized access
• Obligation policies determine what activates a
  subject is allowed to perform
• Authorization policies can be used for
  configuration phase and Obligation policies used
  to determine load balancing behaviors

7
System Model

• High Level View

8
System Model

• Traditional solution for SIP and VMS integration

9
System Model

• GEN based with load balancing

10
System Model

• BD is processed, eligible SIP UA apply to join
  group, first group message is sent.
• All SIP UA constantly listening at SGCC, NEXT is
  chosen, second group message is sent.
• It contains all the group members and identity of
  NEXT

11
System Model

• Significance of NEXT is that it is the elected
  leader to handle the session. NEXT sends
  InviteAck to show it is the call-handler
• During passing of NEXT, there is a timeout period
  to remove crashed members.

12
Behavior Definitions
13
Conclusions

• Traditional solution is not dynamic
• Addition and removal of SIP UA requires a
  reconfiguration of the system
• It has selection latency because it has to go
  through a database to find a suitable SIP UA
• GEN-based model does not need reconfiguration
  when SIP UA are removed or added (self-organizing
  behavior)
• It will also have a smaller selection latency
  with a NEXT available strategy