International Telecommunication Union
Common VoIP Metrics
Alan Clark
CEO, Telchemy
Workshop on End-to-End Quality of Service.What is it? How do we get it?
Geneva, 1-3 October 2003
Summary
ITU-T
o Typical VoIP Problems
o Management Requirements
o Common Metrics proposal
o Media path reporting
o Reporting through signaling protocols
o RTCP XR
o Applications examples
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
2
IP related problems
ITU-T
Gateway
Gateway
Lost Packets
Delay &
Jitter
CODEC
Packet discards
by jitter buffer
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
3
Non-IP related problems
ITU-T
Signal Level too
High or low
Hybrid
VoIP
Gateway
Echo
Canceller
Uncanceled
echo
1-3 October 2003
Echo from
Unbalanced
Hybrid
Workshop on End-to-End Quality of Service. What is it? How do we get it?
4
VoIP Metrics Reporting
ITU-T
Signaling
based
reporting
IP
Endpoint
1-3 October 2003
Call
Control
Media path
reporting
Network
Management
reporting
IP
Endpoint
Workshop on End-to-End Quality of Service. What is it? How do we get it?
5
Signaling System Reporting
ITU-T
End of call message
Call
Control
Voice over IP quality
metrics
IP
Endpoint
1-3 October 2003
Integrates call quality data into
CDR system, supports service
management / billing
Workshop on End-to-End Quality of Service. What is it? How do we get it?
6
Media Path Reporting
ITU-T
IP
Endpoint
Media path
reporting
IP
Endpoint
Allows information to be exchanged between
endpoints
Allows information to be sent through firewalls
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
7
Management Reporting
ITU-T
Management
System
SNMP
“Get”
IP
Endpoint
1-3 October 2003
Provides access to information
on an “as needed” basis
Integrates with current NMS
Workshop on End-to-End Quality of Service. What is it? How do we get it?
8
Common VoIP Metrics?
ITU-T
o Equipment needs only count/ measure
one set of metrics regardless of the
protocol used for reporting
o Network manager/ operator can see the
same set of data regardless of how it
was reported
o Drive the equipment vendors towards a
common “sensible” metrics set
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
9
RTCP XR protocol
ITU-T
Loss rate
Discard rate Burst density Gap density
Burst duration (mS)
Gap duration (mS)
Round trip delay (mS)
End system delay (mS)
Signal level
RERL
Noise level
Gmin
R factor
Ext R
MOS-LQ
MOS-CQ
Rx Config
-
Jitter Buffer Max
1-3 October 2003
Jitter Buffer Nominal
Jitter Buffer Abs Max
Workshop on End-to-End Quality of Service. What is it? How do we get it?
10
RTCP XR applications
ITU-T
GW
Provides several key functions:
- Exchange information between endpoints to
support more comprehensive call quality estimates
- Allows mid-stream systems to monitor endpoint
QoS, even if RTP payload encryption is used
- Supports exchange of endpoint measured QoS
where endpoint is in different management domain
- Supports endpoint adaptation
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
11
ITU-T
Migrating into signaling
protocols
o RTCP XR – IETF AVT group
• In RFC editor queue – RFC in October?
• Already being implemented by manufacturers
o H.323 …. H.460.9 Annex 2
• Consent in January 2004?
o H.248 …. H.248.rtcpxr
• Consent in January 2004?
o SIP ….. New work in IETF
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
12
Generating VoIP Metrics
ITU-T
RTCP XR
End of Call
Signaling
Loss/
Discard
“Software
Probe”
CODEC
DSP
Signal
Noise
RERL
200 IPS
IP Phone or Gateway
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
13
ITU-T
Accumulating endpoint metrics
in Gateway
SNMP or
Bulk upload
C”Q”DR
PCM
Soft
Probe
RTCP XR
IP “cloud”
SNMP MIB based around RTCP XR metrics
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
14
Example – IP Centrex
ITU-T
Service Provider
domain
Access link
congestion
LAN
congestion
IP
Phone
IP Network
Passive hub or
shared Ethernet
segments
Softswitch
NO VISIBILITY
OF PROBLEMS
1-3 October 2003
Poorly
located
server
Workshop on End-to-End Quality of Service. What is it? How do we get it?
15
Solution to IP Centrex problem
ITU-T
Access link
congestion
LAN
congestion
IP
Phone
IP Network
Softswitch
Real time reporting
through RTCP XR
provides feedback
on Service Quality
Management
System
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
16
Summary
ITU-T
o Equipment needs only count/ measure one set of
metrics regardless of the protocol used for reporting
o Network manager/ operator can see the same set of
data regardless of how it was reported
o Drive the equipment vendors towards a common
“sensible” metrics set
o Already gaining support within the industry:
• Nine+ test equipment vendors will be supporting RTCP XR
decodes by the end of 2003
• At least three major IP equipment manufacturers
expected to be supporting RTCP XR by the end of 2003
• Three major DSP software vendors providing support for
this architectural model by the end of 2003
1-3 October 2003
Workshop on End-to-End Quality of Service. What is it? How do we get it?
17