Overview
– What is Signaling– Signaling Layers– Signaling Protocol– ATM Addressing– ILMI– Signaling Setup– Practice
What is Signaling?
• Mechanism by which users identify to whom they want to be connected
• Dynamic on-demand method for customers to communicate, the type of connection desired and the attributes of the connection
• Signaling is a “Control Plane” function that “automates” setting up a connection Predefined VCI = 5 Uses AAL5
• Signaling, in conjunction with Call Processing in conjunction with Traffic Management and subscriber information, allocates the VPI/VCI to be used for the connection and communicates this back to the user
Switched Virtual Connections (SVC)
Call Processing
Why SVCs?
Flexible connectivity
More efficient resource utilization
Automated
Transparent to User
Signaling channel predefined as VCI = 5
Messages (Q.2931 layer 3 protocol) exchanged from User to Switch Call Processing to request & setup connection
Assured Information Transfer
• AAL 1, 2 & 5 do not provide assured transfer (eg. re-transmission in the event of error)
• SSCOP (Service Specific Connection Oriented Protocol) uses sequence numbers and other controls to acknowledge or effect re-transmission of messages
• SSCOP can be placed above AAL 3/4 or 5
• SSCOP is example of SSCS (Service Specific Convergence Sublayer) protocol
• Used with signaling for reliable connection establishment and support reliable communications about a connection
Switched Virtual Connections (SVC)
UserSVC
SupportQ.2931/UNISig Messages &
Procedures
UpperLayer
Applications
PhysicalLayer
ATM(Cell)Layer
ATMAdaptation
Layer
Q.2931 Data
VPI/VCI = 0/5
SAALSSCOP Q.2931 Data
AAL5 • • • • • •
SAAL: Signaling AAL SSCOP: Service Specific Connection Oriented Protocol
Simple Call Setup of a Connection
Connect Ack
Setup
SetupCall
ProceedingCall
Proceeding
Connect
ConnectConnect Ack
NNINNIUNIUNI
UNIUNI
VPI/VCIassigning VPI/VCI
assigning
Release of a Connection
Release
Releasecomplete
NNINNIUNIUNI
UNIUNI
Release
Releasecomplete
Release
Releasecomplete
Setup Message Elements
• Connection identifier
• Called party number
• Calling party number
• ATM user cell rate(s)
• QoS parameter(s)
• AAL parameters
UNI/Q.2931 Signaling
Root(originator)
Leaf A
Leaf B
Leaf C
Unidirectional information flow
Distributed tree topology using ATM switch multicast function
Rapid connection setup supported
Dynamic adding and clearing of endpoints
Signaling messages in VCI = 5
Procedures similar to ISDN Q.931 but simplified
Point-to-multipoint example
UNI/Q.2931 Addressing
ISO = International Standards OrganizationNSAP = Network Service Access Point
Supports multiple addressing formats
E.164 (Telephones) - 15 digitsISO NSAP (Internet) - 20 bytes - three formats possible
Data Country Code (DCC)International Code Designator (ICD)Private E.164 Address
E.164 & NSAP
SNNDCCC
15 Nibbles
E.164
ID
CC: Country Code NDC: National Destionation Code SN: Subscriber Number ESI: End System Identifier SEL: Selector
„F“
Example: 00049 2407 95860 F
NSAP Prefix ESI SEL
12 Byte 6 Byte1 Byte 1 Byte
47 0049240795860005320A4801 005066000028 00Example:
ILMI
Integrated Local Management Interface (ILMI)
Based on SNMP
Automatic retrieving and exchange of Interface information (UNI) between TE and a network device
ILMI Protocol
Power on Cold startClear tables
ATM Address: ATM Address:
______.ESI Prefix.___
Get address
No entry
Set Prefix
No error
Prefix.ESI
Set Address
No errorPrefix.ESI
ATM Vision Installation
sysconf atm
Show actual values of ATM settings:
sysconf atm vp <Number>
Set VP for signaling:
sysconf atm ilmi enable
Enable ILMI protocol:
sysconf atm ilmi poll
Enable ILMI polling:
ATM Vision and SVC
sysconf atm p2mp enable
Allow point-to-multipoint (p2mp) connections:
sysconf atm signaling enable
Enable signaling:
sysconf atm uni <Version><Version> = 3.0 | 3.1 | 4.0
Set user network interface (UNI) version:
ATM Vision and SVC
Bandwidth and VPI/VCI restrictionof Line- and Cascade Interface:
root@Karlsruhe:/> sysconf port ?usage: sysconf port sysconf port show sysconf port line pcr <pcr>|link sysconf port casc pcr <pcr>|link|none sysconf port casc vpi any sysconf port casc vpi <min> <max> sysconf port casc vci any sysconf port casc vci <min> <max> sysconf port casc special enable|disableroot@Karlsruhe:/>
Note: If the Cascade Interface is configured to special disable, the VCI range 0..31 will be discarded
Setting up SVC
video -s <Channel> <Bitrate> <AESA> [Flags]
Setting up a video SVC:
atmaddr
Getting Systems ATM End System Address(AESA):
Section
Practice
What is Signaling
Signaling Layers
Signaling Protocol
ATM Addressing
ILMI
Signaling Setup
Hands on: SVC
INFAN
ETHERNET 2 ETHERNET 1
IN
ASI
OUT1 OUT2
ASI
RX
SO
RA
TX
LO
LP
L IN E IN TE RFA CE
I N O U T
OUT1 OUT2
ASI
INFAN
ETH ER N ET 2 ETH ER N ET 1RX
SO
RA
TX
LO
LP
L IN E IN TE R FA C E
I N O U T
O U T 1 O U T 2
A S I
SD
Catalyst8500
Power Supply 0CISCO YSTEMSS Power Supply 1
SwitchProcessor
SERIES