VOIP Switch Monitoring and Traffic Management-Final.ppt

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VOIP Switch Monitoring and
Traffic Management
Habib Madani
Syed Khurram

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Agenda
• Overview of Softswitch
• Voip Softswitch Call Processing Overview
• Protocols
• Call Flows
• Softswitch Operations
• Trend analysis
• Summary

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Agenda
• Protocols
• Call Flows
• Trend analysis
• Summary

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Overview of Softswitch
• Network Overview
• Network Configuration
• Broadband Local Integrated Services Solutions

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Network Overview
• The BTS 10200 call agent offers telephony services over
IP and ATM networks.
• BTS 10200 provides call control intelligence for
establishing, maintaining, routing, and terminating voice
calls through the IP or ATM network via media gateways,
while seamlessly operating with the PSTN
• Supports Class 5 level services, such as 911 emergency,
call forwarding and caller ID
• Also provides support for messaging and announcements

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IP
Network Configuration
ANNOUNCE-
MENT
SERVER
AS5300
AS5300
PSTN
CO
3660
ISDN
PBX
ISDN
PBX
AS5300
UBR
CISCO
2600
CAS
PSAP
911
Voice
Mail
SERVER
SS7
STP
SS7
STP
D-Channel Backhaul
MGCP
SIP
RUDP
SS7 Links
T1/Analog Lines
BTS
10200
Another
BTS 10200
or
Call Agent

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BLISS-T1 Signaling Interfaces
ISDN
Backhaul
FCP
CA
Feature
Servers
Announcement
Server
Trunking
Gateway
PRI
PBX
Cisco
SIP Voice Mail
Server
IMT
CO
Network Management
& Operational Support
Systems
SNMP, CORBA, TELNET,
FTP, CLI, HTTP
IP Network
CA
SIP-T
SS7 STP

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Agenda
• Protocols
• Call Flows
• Trend analysis
• Summary

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VOIP Softwitch Call Processing Overview
• ISUP trunking
• Emergency Services
• Trunking gateway for operator services
• Voice mail services
• Announcement services

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SS7 Links
IMTs
MGX
IAD
C4/C5
BTS
STP
ISUP Trunking Gateway
• Routes offnet calls to ILEC or IXC
over Inter-machine Trunks (IMTs)
• High port density
• Interconnects SS7 links b/w IP
Transfer Point (ITP) and C4/5 via
STPs
• BTS should be provisioned
trunks of the same trunk group
across multiple TGWs for
redundancy
• Sigtran used to backhaul ISUP to
BTS CA for call control
RTP
MGCP
MGCP
V
SCTP

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MF/CAS Trunks
IAD
BTS
RTP
Primary
PSAP
E911
Tandem
Trunking Gateway for 911 Services
• Uses Feature Group D, Operator
Service (OS) signaling protocol
• TGW requires support of MGCP
CAS “MO” package as described in
“draft-foster-mgcp-cas-packages-
00.txt”
• 2 types of 911s: enhanced 911 and
basic 911
B911 has PSAP (Public Safety Answer
Point) connect directly to TGW
E911 has PSAP connect TGW via
tandem switch
• 911 requires “keep the circuit up
even if the caller hangs up”
• 911 trunks recommended connected
to multiple TGWs for redundancy
Selective
Routing Database
Alternate
PSAP
Automatic
Location ID
MGCP
MGCP
MGX
V

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MF/CAS
Trunks
IAD
BTS
RTP
Operator
Postions (OPs)
Tandem
Switch
Trunking Gateway for Operator Services
• Uses Feature Group D, Operator
Service (OS) Signaling protocol
• TGW requires support of MGCP
CAS “MO” package as described in
“draft-foster-mgcp-cas-packages-
00.txt”
• BTS sends Preferred Carrier Info to
tandem switch to determine
appropriate operation position
• OS does not have “keep the circuit
up even if the caller hangs up”
requirement as 911
• OS trunks recommended connected
to multiple TGWs for redundancy
MGCP
MGCP
MGX
V

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LDAP
IMAP
SMTP
Directory
Server
Message
Server
SIP
UC App.
Server
IAD
BTS
Application
Services
Backend
Services
RTP
MGX
Voice Mail Server
Voice Mail Server
• Provides voice messaging
capabilities
• Components
UC Applications Server
VM SW resides. Terminates calls,
records and replays messages, and
interacts with backend servers
Directory Server
Stores subscriber profiles and
information about which greetings
are active and where greetings are
located
Message Server
Stores and retrieves personal
greetings, subscriber messages,
and distribution lists2
MGCP
MGCP
V

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BTS
IAD
AS
Announcement Server
• Instructed by BTS with MGCP to play
announcement RTP to ingress MG (MTA
or MGX)
• Audio files are stored in AS
• MGCP package options for AS:
Script (MG requires scripting language
support such as TCL)
Announcement Server
• Deploy multiple AS for redundancy
This # has been
disconnected.
Please check
your # again.
RTP
MGX
MGCP
MGCP
V

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Agenda
• Protocols
• Call Flows
• Trend analysis
• Summary

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Protocols
• SIP Methods
• MGCP Implementation
• MGCP Commands
• MGCP Modes
• ISDN
• Channel Associated Signaling (CAS)
• CAS - PSAP/911

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SIP Methods
•Consists of Requests and Responses
•Requests (unless mentioned, each has a response)
- REGISTER UA registers with Registration Server)
- INVITE (request from a UA to initiate a call)
- ACK (confirms receipt of a final response to INVITE)
- BYE (sent by either side to end a call)
- CANCEL (sent to end a call not yet connected)
- OPTIONS (sent to query capabilities)
•Messages contain SIP Headers and Body. Body might be
SDP or an attachment or some other application
**UA=User Agent (end device)**

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MGCP Implementation
• Communication between the BTS 10200 call agent and the
media gateway (MGW) is done via MGCP
• MGCP uses a sequence of commands and mandatory
acknowledgements
• Commands contain a requested verb (action to be
performed by endpoint) and additional parameters

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MGCP Commands
• NotificationRequest-issued by CA instructing the MGW to watch for
specific events, such as hook actions or DTMF tones on a specified
endpoint (RQNT)
• Notify-used by the MGW to inform the CA when the requested events
occur (NTFY)
• CreateConnection-used by the CA to create a connection that
terminates at an endpoint inside the MGW (CRCX)
• ModifyConnection - used by the CA to change parameters associated
with a previously established connection (MDCX)
• DeleteConnection - used by CA to delete an existing connection or by
MGW when an existing connection can no longer be sustained (DLCX)

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More MGCP Commands
• AuditEndpoint - used by CA to audit the status of the endpoint (AUEP)
• AuditConnection – used by CA to retrieve the parameters attached to a
connection (AUCX)
• RestartInProgress - used by MGW to notify the CA when the gateway or
a group of endpoints on the gateway are taken out of service or being
placed back in service (RSIP)

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ISDN
• Backhaul
- Terminology for sending
messages between CA - PBX
through the AGW
• ISDN-Q.931
- Normal application layer
messages sent to the CA over IP
• RUDP
- Cisco proprietary protocol that
makes UDP Reliable
ISDN-Q.931
UDP
IP
Backhaul
RUDP

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ISDN Network Diagram
RUDP – Signaling and Call Setup/Teardown on
the D-Channel
MGCP – Voice, data, or video on the B-Channels
IP
ISDN
PBX
ISDN
PBX
AS5300
D-Channel Backhaul
MGCP
BTS
10200

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Channel Associated Signaling (CAS)
• Inband signaling made up of tones carried on the same
circuit as the call they are setting up
• Implemented via MGCP to support PBX connectivity
• Dual Tone Multi-frequency (DTMF) refers to the signaling
(tones) generated when you touch a button on a push
button pad
• MGCP supports all the DTMF/MF
(signaling types: DTMF loopstart, DTMF groupstart, DTMF imstart, DTMF
winkstart, MF FGD, MF imstart, MF winkstart,)
• CAS is required to:
Support PBX interconnect and incoming CAS trunk interconnects
Support Barge-In and Busy-Line Verification operator services (operator
interrupt services) – Not supported release 1.0
Support PSAP/911 services

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CAS - PSAP/911
• 911 services require support for MF signaling
• PSAP operators must be able to hold the line even if caller
goes on-hook

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Agenda
• Protocols
• Call Flows
• Trend analysis
• Summary

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Call Flow
• CA to CA Call Flow – SIP
• RG to RG
• TG - RG Using ISDN - MGCP Signaling
• PBX/ISDN PRI to RG
• Barge-In/Busy Line Verification
• BLV/BLI Call Flow

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CA to CA Call Flow - SIP
CA-2 PSTN2
CA-1
PSTN1
1. IAM
2. Invite
3. IAM
4. 100 Trying
5. ACM
6. 183 Progress
7. ACM
8. ANM
9. 200 OK
10. ANM
12. Talking
13. REL
14. RELC
15. Bye
16. REL
17. RELC
18. 200 OK
19. ACK
11. ACK

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BTS
10200
RG-o
RG-t
1. Off-hook
5. digits
2. NTFY (O:hd)
200 OK
3. RQNT (R:hu (N))
200 OK
4. RQNT (R:hu, hf, [0-9:#*T](D), S:dl)
200 OK
6. NTFY (O:9,1,6,3,4,2,1,2,1,2,T)
200 OK
7. RQNT (R:hu, hf)
200 OK
916-342-1206 916-342-1212
8. CRCX (M:recvonly)
200 OK orig. SDP
Hey Call Agent, I’m
going off hook
Hey endpoint, let me
know if your
subscriber hangs up
Hey endpoint, let me know if your
subscriber hangs up, hook-flash or
dials digits. Oh and signal dial tone
to your subscriber
Hey Call Agent, I am letting you
know that I have collected digits
Sure, but let me know if your
subscriber hangs up or hook-
flash
I am going to create a
backwards audio path to you in
case some in-band info is played
by an endpoint.
Endpoint ACKs with his SDP
info
Onnet Call – RGW to RGW

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BTS
10200
RG-o
RG-t
200 OK with term. SDP
10. MDCX (M:recv only, term. SDP)
200 OK
916-342-1212
9. CRCX (M:sendrecv orig. SDP)
11. RQNT (R:hd S:rg)
200 OK
12. Ringing
14. Ring Back
15. Off-hook
16. NTFY (O:hd)
200 OK
17. RQNT (R:hu, hf)
200 OK
13. RQNT (R:hu S:rt)
200 OK
Hey endpoint 2, you
have a caller. Creating
bi-directional path to
you with orig. SDP info.
Hey end endpoint 1, I
am sending you the
term. endpoint SDP
information
Hey, ring the
phone.
Hey, play a ring back
tone, the termination is
ringing too.
Hey call agent, my
subscriber answered the
phone
Ok, but let me
know if he
hangs up

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BTS
10200
RG-o
RG-t
18. MDCX (M:sendrecv)
200 OK
916-342-1212
19. RQNT (R:hu, hf)
Bi-Directional Voice Path
200 OK
200 OK
20. On-hook
21. NTFY (O:hu)
23. DLCX
250 Connection Deleted
22. RQNT (R:hd)
200 OK
I am making your
connection bi-directional
so you can talk to your
buddy and hear him Hey endpoint, let
me know if your
subscriber hangs
up or hook-flashes
Hey call agent, my
subscriber went
on-hook.
OK, but let me
know if your
subscriber goes
back off-hook.
Ok I am deleting
the connection to
you because the
originating
subscriber is now
on-hook.
Conversation:
Aunt Pearl tells Sally
about her new groovy
hairstyle

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BTS
10200
RG-o
RG-t
916-342-1212
25. RQNT (R:hu)
24. DLCX
250 Connection Deleted
26. RQNT (R:hd)
200 OK
200 OK
28. NTFY (O:hu)
29. RQNT (R:hd)
200 OK
200 OK
Deleting your
connection because
you went on-hook Let me know if
your subscriber
goes on-hook.
Let me know if
your subscriber
goes off-hook
27. On-hook
Hey my subscriber went
on-hook
Ok, but let me know if
your subscriber goes
off-hook.

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TG - RG Using ISDN - MGCP Signaling
endpoint/1@rg2.cisco.com
IP
endpoint/1@tg1.cisco.com
ISDN
Backhaul
User 1 User 2
RG-2
PBX
BTS
10200
TG-2

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TG-3
EO/
User 2
PBX
User 1 TG-1 RG-2
User 3
PBX/ISDN PRI to RG
SETUP
CRCX
(M:recvonly)
14. Off-hook
ACK
(SDP1) CRCX
(M:sendrecv,
SDP1)
ACK
(SDP2)
13. Ring back tone
Alert
SETUP
Backhaul
CALL PROC
MDCX
(M:recvonly
SDP2)
ACK
12. Ringing
RQNT
(R:hd, S:rg,
rbk(xxx))
10. ACK
BTS
10200
CALL PROC
Aler
t

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BTS
10200
TG-3
User 3
EO/
User 2
PBX
User 1 TG-1 RG-2
22. CONN ACK
19. MDCX
(M:sendrecv)
20. ACK
16. OK
15. NTFY
(O:hd)
21. CONN
18. ACK
17. RQNT
(R:hu)
23. Bearer Connection Established
PBX/ISDN PRI to RG (cont'd)

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Barge-In/Busy Line Verification
• Permits operators to establish a connection to a
customers line to verify a busy condition
• Operator access is provided over dedicated facilities
• Facilities connect directly to a switchboard or via a
switched network accessed by remote operator systems
• The trunks may use reverse battery loop or E&M lead
supervision with multi-frequency (MF) or dial pulse (DP)
signaling

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BTS
10200
BLV/BLI Call Flow
Caller C
B -TG/RG Operator
A-RG TG
Conversation
seize
NTFY (O:MS/sup)
ACK
wink-start
RQNT (R:MS/inf,MS/rel)
CRCX (M: inactive, SDPc)
digits
ACK(SDPc)
NTFY(O:MS/inf(digits))
CRCX (M:recvonly)
ACK
ACK(I: BLV-2, SDPa)
MDCX (M:reconly,S:MS/ans, SDPa)
ACK
answer
MDCX (M: confrnce,I:BLV-1)
ACK
Operator reports
line is busy
MDCX (M: confrnce,I:BLV-2)
MDCX(M:sendrec)
ACK
Conversationa
3-way call activeb

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Agenda
• Voip softswitch Call Processing Overview
• Protocols
• Call Flows
• Trend analysis
• Summary

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Softswitch Operations
• Network management and Performance Counters
• Network Performance- Voice Quality
• Defining jitter, packet loss and latency
• VOIP Switch Performance Counters
• Performance Counters Flow
• Types of Counter on CISCO BTS
• Performance counter monitoring

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Network management and Performance Counters
• One of the key Network Management aspects is monitoring Performance
counters or Performance Pegs.
• Performance counter collection and reporting
Typically in NMS/EMS and NE the Performance data is collected as reports.
Performance counters are collected in various time buckets, these buckets keep
historic and pseudo-real time data. The pseudo-real time buckets can be reset for
immediate trouble shooting.
These reports are also periodically dumped to disk as flat files. These files are
then pulled off to a data store to perform Data mining.
• Common Service Provider (SP) usage
Preemptive trend analysis for capacity planning
Service Level Agreements (SLA)
Quality of service monitoring and network trouble shooting.

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Network management and Performance Counters
cont ..
• How do we measure network performance?
• VOIP network Key Measurements are based of Call
Success Rate , Voice Quality and Voice Mail access
% Ineffective Attempts
Network issues: IP backbone partially down, DNS
servers partially down, voicemail trunk congestion,
HFC/Cable plant capacity.
No Channels available for Off-net PSTN calls.
% Dropped Calls
OR IP backbone completely down, total outage
Call Processing Failure at the PSTN, signalling link is
down or the bearer trunks are down.
• Thus all these factors are deterministic of VOIP
network performance and they need to be
effectively monitored.

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Network Performance- Voice Quality
• It is dictated by Mean Opinion Score or MOS in short.
• How listeners perceive voice quality.
• Key Factors affecting Voice Quality for VOIP network:
Jitter
Delay in packet loss
Latency

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Defining jitter, packet loss and latency
• Delay is the time taken from point-to-point in a network.
Delay can be measured in either one-way or round-trip delay.
VoIP typically tolerates delays up to 150 ms before the
quality of the call is unacceptable
• Jitter is the variation in delay over time from point-to-point. If
the delay of transmissions varies too widely in a VoIP call,
the call quality is greatly degraded. VOIP Network
compensates for this by having jitter buffers.
• Packet loss is losing packets along the data path, which
severely degrades the voice quality.

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Performance Counters and VOIP Switch Vendors
• Current Performance Counter Availability
Currently Counters are available through private Interfaces which capture the VOIP call
segments.
ISUP counters for PSTN signaling, SIP counters , MGCP counters for trunk gateways,
general Call processing counters and QOS counters.
• Industry Standard for VOIP monitoring
To Monitor VOIP Performance, Standard collection and polling mechanisms should
available through SNMP/MIBS, CORBA/IDL, CMIP/Q3.
• Alerting based of the Performance Counters
The VOIP switch vendors need to implement configurable thresholds mechanisms,
acting as a high/low/variable water marks.
These watermarks would act as triggers for alarms and events, allowing real time
monitoring of the System.
• There is a lack of composite monitoring standard
It would dictate guidelines for Performance counters, collection
mechanism Alert trigger and generations.

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Performance Counters Flow
Provider Backbone
HFC Plant
LNP
STP
PSTN
Signaling GW
MG
V
CMS/
SoftSwitch
MGC
DOCSIS
CMTS
VM
CONF
SRV
ANN
SRV
Media Servers
CALEA
NCS EMTA
NCS EMTA
CM
NCS MTA
Dqos Counters
MGCP Counters
SIP Counters
ISUP Counters
Dqos Counters

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Case Study leveraging counters available on
CISCO BTS
• CISCO BTS offers a wide set of performance counters
through its private interfaces SNMP MIB being one of them.
• The following set of BTS counters capture system health
across various VOIP call segments:
ISDN User Part (SS7/PSTN) signaling protocol related
information.
MGCP signaling protocol related information.
SIP Interface Adapter related information
Call Processing specific information
Trunk Group usage information
Dynamic Quality of Service related information

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Agenda
• Voip softswitch Call Processing Overview
• Protocols
• Call Flows
• Trend analysis
• Summary

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Case Study for Trend Analysis
• Trend Analysis and Visual Monitoring of Performance Counters
• Architecture of DDRAW setup
• DDRAW Dash Board in depth
• Trend Analysis using Call Performance counters
• Trend Analysis using MGCP Performance counters
• Trend Analysis using ISUP Performance counters
• Trend Analysis using Dynamic Qos Performance counters
• Trend Analysis using SIP Performance counters
• Trend Analysis for PSTN Bearer Trunks

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Trend Analysis and Visual Monitoring of
Performance Counters
• BTS performance data collection
BTS performance data was collected for a USA CABLE MSO.
The reports were collected at 15 min. buckets for 24 hour, and
dumped to flat files (CSV). 3 months worth of these data was
collected.
• Pull data
The data was ftped over to a linux server which had Perl, Round
Robin Database(RRD) and DRRAW(cgi) installed on them.
• RRD update
Perl was used to parse the CSV files and RRD was updated with 3
months of cable MSO performance data.

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Trend Analysis and Visual Monitoring of
Performance Counters (cont.)
• DDRAW was customized to create a Dashboard for some
of these counters.
• RRD and DRRAW
we have a pseudo real-time display of the performance stats.
This Dashboard displays past 28 hours, 1 week, month and
year of data.
• It can be used to create a system wide view of the VOIP
call flow, do capacity planning, and keep on top of SLA.

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Architecture of DDRAW setup
BTS 01
BTS 02
BTS 03
RRD
Perl Script
Parsing
Parse Data
Populate Data
Client View
HTTP
Pull Data
Pull PM Data
Linux Server
Client
Client
MGCP
Callp
ISUP
DRRAW
CGI
DRRAW CGI
Apache

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Dash Board in depth
• Call Stats Dash Board display, captures, the
number of originating call attempts of all types,
call attempts, call originating failures and call
success on the reporting BTS.
• DQOS Dash actually looks ok, which reflects
the CMTS leg, it shows that the Gate SET
attempts are equal to the Gate SET Successes.
• MGCP Dash shows number of mgcp attempt
success, fail or abandon

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Dash Board in depth cont ..
• ISUP Dash shows SS7 signaling pattern, which includes
number IAM, ANM and REL message
• SIP Dash shows number of SIP messages going thru the
switch
• Trunk Dash shows utilization of trunk and overflows- Which
may help in capacity planning

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Trend Analysis using Call Performance
Counters
• It can easily be seen that there is a pattern.
• Where the peaks represent the busy hour. Any
deviations from these patterns represents anomalies
that would need to be investigated by the Service
Provider.
• Also we see a clear gap between the Success and the
Call originations, this gap indicates that we are
losing calls.
• It could be a result of hang-ups, busy dial, or
network problems.

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Trend Analysis using Call Stat counters –
Example

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Trend Analysis using Call Stat counters –
Example cont.

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Trend Analysis using MGCP Performance
counters
• It can help monitor any performance issues in the network
just by reviewing ave mgcp attempts and failures.
• Information can be segregated by gateway which could be
related to trunking gateway or announcement server.

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counters – Example

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counters – Example cont.

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Trend Analysis using ISUP Performance
counters
• It can identify issues related to PSTN signaling, or any ss7
link problems.
• The Dashboard example is showing IAM,ANM,REL
counters being monitored.
• Any anomaly related to PSTN network/usage related to
incoming/outgoing PSTN calls would be visible.
As an example drop in IAM would clearly indicate the call
originations are having issues.

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counters - Example

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Trend Analysis using Dynamic Qos
Performance counters
• COPS protocol
Gate Sets attempts, Success and Commits are tracked
• Problem trend
Network problem related to CMTS are visible through these Gate
counters.
A difference in Gate Set attempts and Gate Set Success would
be a clear indication of CMTS resource allocation issue.
A slight deviation from the norm could be an indication of a
problem before SP starts experiencing it.
• DQOS parameters of Jitter, Latency and Packet loss are also
collected by the BTS and can be monitored in this way.

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Trend Analysis using Dynamic QoS
counters – Example

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Trend Analysis using Dynamic QoS

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Trend Analysis using SIP Performance
counters
• BTS uses SIP to interact with VOICEMAIL equipment and
SIP trunks.
• Dash Board SIP Counters
SIP Outgoing messages, SIP Outgoing Success,5xx Errors
• Problem trends
An increase in retransmits or increase in 5xx errors is a
visible indication that Voice mail server or SIP trunks is
having issues.

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Trend Analysis using SIP counters –
Example

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Trend Analysis using SIP counters –
Example cont.

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Trend Analysis using Trunk Usage Counters
• Dash Board Trunk Counters
Trunk total overflow, Incoming Trunk Busy, Outgoing trunk Busy, Total
Trunk usage.
• A pattern is seen
we can see that most of the trunk seizers are for outgoing trunks.
Incoming trunk seizures are low.
Overflow of trunks is very low.
• Problem indication
Total Trunk Usage goes high, Overflow of trunks goes high are
indications of capacity issue.

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Trend Analysis using Trunk usage counters
– Example

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Trend Analysis using Trunk usage counters
– Example cont.

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Summary
• VOIP switch technology is a new field.
• Performance counter aspect of network management can be a
key factor in monitoring the network for issues of equipment
malfunction, degradation and capacity.
• To provide seamless customer experience from traditional to
softswitch, this will help us identifying issue proactively.
• A monitoring strategy is to use RRD and Drraw, for monitoring
the system through pseudo real time graphs at the NOCs.

VOIP Switch Monitoring and Traffic Management-Final.ppt

VOIP Switch Monitoring and Traffic Management-Final.ppt

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