Transcript Chapter 10 Lecture Presentation

Chapter 10
Advanced Network
Architectures
Contained Slides by Leon-Garcia
and Widjaja
Chapter 10
Advanced Network
Architectures
MPLS
What is MPLS?
LER
IP


IP
L1
LSR
IP
L2
LSR
IP
L3
LER
IP
Multiprotocol Label Switching (MPLS)
A set of protocols that enable MPLS networks



Packets are assigned labels by edge routers (which
perform longest-prefix match)
Packets are forwarded along a Label-Switched Path (LSP)
in the MPLS network using label switching
LSPs can be created over multiple layer-2 links


ATM, Ethernet, PPP, frame relay
LSPs can support multiple layer-3 protocols

IPv4, IPv6, and in others
Why MPLS?


Labels enable fast forwarding
Circuits are good (sometimes)




Conventional IP routing selects one path, does
not provide choice of route
Label switching enables routing flexibility
Traffic engineering: establish separate paths to
meet different performance requirements of
aggregated traffic flows
Virtual Private Networks: establish tunnels
between user nodes
Separation of Forwardng &
Control
All proposals leading to MPLS separate forwarding and control
Control component
Routing and
signaling
Routing
and
signaling
Routing and
signaling
Routing
tables
Labeled
packets
Forwarding
tables
Switch
fabric
Forwarding component
Labeled
packets
Before MPLS: forwarding &
control intertwined
 Transition to CIDR
(control) meant forwarding
had to change to longestprefix match
With MPLS: forwarding &
control are separate
 All forwarding done with
label switching
 Different control schemes
dictate creation of labels &
label-switched paths
 Control & forwarding can
evolve independently
Labels and Paths
Ingress LSR
Ingress LSR
Ingress LSR
Egress
LSR
Ingress LSR
Ingress LSR


MPLS domain
Ingress LSR
Label-switched paths (LSPs) are unidirectional
LSPs can be:


point-to-point
tree rooted in egress node corresponds to shortest
paths leading to a destination egress router
Forwarding Equivalence Class
IP1
IP1
IP2
IP1
LER
IP2 L1
IP1 L1
LSR
IP2 L2
IP1 L2
LSR
IP2 L3
IP1 L3
LER
IP2
IP2

FEC: set of packets that are forwarded in the same manner






Over the same path, with the same forwarding treatment
Packets in an FEC have same next-hop router
Packets in same FEC may have different network layer header
Each FEC requires a single entry in the forwarding table
Coarse Granularity FEC: packets for all networks whose destination
address matches a given address prefix
Fine Granularity FEC: packets that belong to a particular application
running between a pair of computers
MPLS Labels
ATM cell
PPP or
LAN
frame


VPI/VCI
Layer 2
header
MPLS
header
Layer 3
header
Label
Exp
20 bits
3 bits
S TTL
1 bit 8 bits
Labels can be encoded into VPI/VCI field of ATM header
Shim header between layer 2 & layer 3 header (32 bits)


20-bit label + 1-bit hierarchical stack field + 8-bit TTL
3-bit “experimental” field (can be used to specity 8 DiffServ PHBs)
Label Stacking
Swap
Swap and Push
Pop and Swap
Pop
Push
A
IP

B
3
C
2 7
D
2 6
E
2 8
F
2 5
G
4
IP
MPLS allows multiple labels to be stacked





Ingress LSR performs label push (S=1 in label)
Egress LSR performs label pop
Intermediate LSRs can perform additional pushes & pops (S=0 in
label) to create tunnels
Above figure has tunnel between A & G; tunnel between B&F
All flows in a tunnel share the same outer MPLS label
Label Distribution

Label Distribution Protocols distribute label bindings
between LSRs
upstream
downstream
Label request for 10.5/16
LSR 2
LSR 1
(10.5/16, 8)
Downstream-on-Demand Mode



LSR1 becomes aware LSR2 is next-hop in an FEC
LSR1 requests a label from LSR2 for given FEC
LSR2 checks that it has next-hop for FEC, responds with
label
Label Distribution
upstream
downstream
LSR 2
LSR 1
(10.5/16, 8)
Downstream Unsolicited Mode



LSR2 becomes aware of a next hop for an FEC
LSR2 creates a label for the FEC and forwards it to LSR1
LSR2 can use this label if it finds that LSR2 is next-hop for
that FEC
Independent vs. Order Label
Distribution Control

Ordered Label Distribution Control: LSR can
distribute label if


LER

It is an egress LSR
It has received FEC-label binding for that FEC from its next
hop
(10.5/16, 3) LSR
(10.5/16, 7)
(10.5/16, 9) LSR
(10.5/16, 8)
(10.5/16, 8) LER
(10.5/16, 6)
Independent Label Distribution Control: LSR
independently binds FEC to label and distributes to
its peers
Label Distribution Protocol
LSR

UDP Hello
UDP Hello
TCP open
Initialization
Label Request
Label Mapping
LSR
Label Distribution Protocol (LDP), RFC 3036




Topology-driven assignment (routes specified by routing
protocol)
Hello messages over UDP
TCP connection & negotiation (session parameters & label
distribution option, label ranges, valid timers)
Message exchange (label request/mapping/withdraw)
MPLS Survivability




IP routing recovers from faults in seconds to minutes
SONET recovers in 50 ms
MPLS targets in-between path recovery times
Basic approaches:



Restoration: slower, but less bandwidth overhead
Protection: faster, but more protection bandwidth
Repair methods:


Global repair: node that performs recovery (usually
ingress node) may be far from fault, depends on failure
notification message
Local repair: local node performs recovery (usually
upstream from fault); does not require failure notification
MPLS Restoration
2
3
4
1

8
5
6
7
Normal operation
2
3

4
1
8
5
6

7
Failure occurs and is detected
2
3
4
1
8
5
6
7
Alternate path is established, and
traffic is re-routed
No protection
bandwidth allocated
prior to fault
New paths are
established after a
failure occurs
Traffic is rerouted onto
the new paths
MPLS Protection
Working path
2
3
1
8
5
Protection
path

4
6
7
Protection paths are setup
as backups for working
paths

Traffic carried on working path
2
3

4
1
8
5
6

7
Failure on working path is detected
2
3

4
1
8
5
6
7
Traffic is switched to the protection path
1+1: working path has
dedicated protection path
1:1: working path shares
protection path
Protection paths selected
so that they are disjoint
from working path
Faster recovery than
restoration
Generalized MPLS

MPLS:




Connection-oriented
Leverages IP routing protocols, with TE extensions, to
provide means for selecting good paths
Provides signaling for establishing paths
With appropriate extensions, Generalized MPLS can
provide the control plane for other networks:



SONET networks that provide TDM connections
WDM networks that provide end-to-end optical wavelength
connection
Optical networks that provide end-to-end optical fiber path
Hierarchical LSPs
TDM circuit
Virtual circuit
A
B
TDM circuit
C
TDM switch


Lightpath
E
F
G
H
Lambda
cross-connect
I
J
LSR
GMPLS allows node with multiple switching technologies to
be controlled by one control component
Notion of “label” generalized:


D
Virtual circuit
TDM slot, WDM wavelength, optical fiber port
LSP Hierarchy extended to generalized labels”

MPLS LSP over SONET circuit over wavelength path over fiber
Chapter 10
Advanced Network
Architectures
Multimedia Networking
Multimedia Internet Applications
Remote
Local
Interactive
Local
Playback
Storage
Download
Multimedia Application Types

Storage/Download


Local playback



On-line playback of multimedia sequences stored on remote
servers
May pause during playback to account for network congestion
Continuous playback



Playback of multimedia sequences from a local disk
Streaming


Capturing/or downloading multimedia sequences to/from storage
devices
Continuous on-line playback of remote multimedia sequences
No pausing allowed
Interactive

Multi-participant interactive multimedia sessions
Multimedia Applications … cont’d
Application
Type
Storage
Download
Example
Video
Production
Application QoS Requirements
Bandwidth
Delay
Jitter
Errors / Losses
High
Medium
Medium
None
High
None
Off-line video
Medium-Hi Medium-Hi
editing
Local
Playback
DVD
Playback
N/A
N/A
N/A
None
Streaming
Real Audio/
Real Video
Low - high
High
Medium
Medium
Continuous
Playback
Live
Broadcast
High
Medium
Low
Medium
Interactive
Audio/Video
Conference
Low
Low
Low
High
Components of Multimedia
Applications

System components

Capture and playback systems

Encoders and Decoders

File storage format and storage devices

Real-time transport protocol (RTP)

Real-time Streaming Protocol (RTSP)

Session Description Protocol (SDP)

Session Initiation/Announcements protocols (SIP/SAP)

H.323 Multimedia Communications
Compatibility Requirements
Compatible
CODEC
Storage
Decoders
Encoders
Network
Multimedia protocol stack
Signaling
Media Transport
MGCP/Megaco
H.323
SDP
RTSP
Reservation
Measurement
RSVP
RTCP
SIP
H.261, MPEG
RTP
TCP
Application daemon
Quality of Service
UDP
IPv4, IPv6
kernel
PPP
Sonet
AAL3/4
AAL5
ATM
PPP
Ethernet
V.34
Chapter 10
Advanced Network
Architectures
Real-Time Transport Protocol
RTCP
RTSP
Real-Time Protocol


RTP (RFC 1889) designed to support realtime applications such as voice, audio, video
RTP provides means to carry:




Type of information source
Sequence numbers
Timestamps
Actual timing recovery must be done by
higher layer protocol

MPEG2 for video, MP3 for audio
RTP Scenarios & Terminology







Chair of conference obtains IP multicast
address & pair of consecutive UDP port #s
Even port #: audio
Odd port # for RTCP stream
Each media sent on a separate RTP session
Fixed-length RTP PDUs sent during session
Each RTP multicasts periodic receiver
reports on RTCP port
Mixers and Translators
RTP Packet Format
0
8
V P X
CC
M
16
Payload Type
31
Sequence Number
Time Stamp
SSRC Identifier
CSRC Identifier





Version (2)
Padding flag
Extension Header Flag
Contributing Source Count (# CSRC IDs)
Marker (significant events, e.g. frame
boundaries)
RTP Packet Format
0
8
V P X
CC
M
16
Payload Type
31
Sequence Number
Time Stamp
SSRC Identifier
CSRC Identifier





Payload Type: e.g. PCM, MPEG2, …
Sequence Number: detect packet loss
Timestamp: sampling instant of first byte
Synchronization Source: ID for synch source
CSRC List: contributing sources to payload
RTP Packet
RTP Control Protocol (RTCP)





RTP companion protocol
Monitors quality of service at receivers
Conveys monitored info to senders
Canonical Name CNAME for each participant
RTCP Packets





Sender Report Packet
Receiver Report Packet
Source Description (SDES)
BYE: end of participation by sender
APP: application specific functions
RTCP Packet
Real Time Streaming Protocol
(RTSP)





RFC 2326
VCR-like user control of display: play, rewind,
fast forward, pause, resume, etc…
One connection for control messages
One connection for media stream
TCP or UDP can be used for the control
channel
RTSP Operations
Web
browser
HTTP GET
Presentation desc.
Web
server
SETUP
Media
player
PLAY
Media
server
Media stream
PAUSE
TEARDOWN
Client
Server
Chapter 10
Advanced Network
Architectures
Session Control Protocols
SIP
Session Initiation Protocol

Session: association involving exchange of
data between Internet end systems


Internet telephone call; multimedia
videoconference; instant messaging; event
notification
Session Initiation Protocol





Setting up, maintaining, terminating session
People & media devices
Multicast or mesh of unicast connections
Support for user mobility
Over UDP or TCP
SIP Protocol




Text-based client-server protocol with syntax
similar to HTTP
Transaction: client request /server(s)
response(s)
Basic signaling through transactions
SIP Request: method invoked


INVITE, ACK, OPTIONS, BYE, CANCEL,
REGISTER
INVITE & ACK used to initiate calls
registrar
INVITE sip: [email protected]
c= IN IPv4 192.168.12.5
m=audio 35092 RTP/AVP 0
(2)
(3)
INVITE sip: [email protected]
c= IN IPv4 192.168.12.5
m=audio 35092 RTP/AVP 0
(4)
(1)
(6)
(7)
SIP/2.0 200 OK
proxy
(8)
ACK
(9)
Media flow
SIP/2.0 200 OK
(5) ringing
SIP System Components

User Agents: software in end system that acts on
behalf of a human user



User Agent Client: to initiate a call
User Agent Server: to answer a call
Network Servers: call routing to establish a call



Proxy Server: receives request, determines server to send
it to, and forwards request; Response flows in reverse
direction
Redirect Server: returns message telling client address of
next server
Registrar: registrations on current user locations
INVITE REQUEST
INVITE request to UAS of desired user



As message passes a SIP device, IP
address of device attached to VIA header


Used for reverse path
Command Sequence header



Use name, e.g. email address, telephone #
Usually IP address or hostname not known
Request method and sequence number
Content type: default Session Description
Protocol (SDP)
Response



UAC sends INVITE request to network server
Request proxied/redirected until server found
that knows IP address of user
Response message contains:



Same Call ID; CSeq; To/From
Reach address to send transactions directly to
UAS
Information about media content
SIP Ethereal Capture


user1 calls user2 using Helmsman User
Agent
This User Agent is available at
www.sipcenter.com
INVITE:
User1 sending out Invite Request for User2
Description of Invite Packet:
Header contains
information about the call.
E.g.. To, From, Via.
TRYING:
User1 trying to connect to User2
Header Description of Trying Packet:
RINGING:
Packet Description:
Connection has been established with
User2, waiting for User2 to answer the
call.
OK and ACK :
Connection has been established
and user1 sends out a “OK” packet
Packet Description for “OK”:
User1 sends an “ACK” packet to user2
Packet Description for “ACK”:
BYE:
User2 wants to
disconnect, sends
a BYE packet
Packet Description for BYE:
User2 is trying to
disconnect and hence
sends “Trying” Packet
“OK” is sent by User2
once call is successfully
disconnected
Chapter 10
Advanced Network
Architectures
Session Control Protocols
H.323 Communications
Systems
H.323 Systems






Support for real-time multimedia communications on
LANs & packet networks
H.323 provides call control, multimedia
management, bandwidth management, interfaces to
other networks
H.323 terminals carry voice, audio, video, data, or
combination
Gateways handle signaling messages between
packet network & other networks
Gatekeeper handles call control inside H.323 net
Multipoint control unit combine media streams
Gatekeeper
MCU
Telephone
Gateway
Public Telephone
Network
IP network
H.323 Terminal
H.323 Terminal
Scope of H.323
Microphone
Speakers
Audio
Codec
Camera,
Display
Video
Codec
Receive
Path
Delay
H.225
Layer
Data
Equipment
System Control
System
Control
User
I/F
H.245 Control
Call Control
RAS Control
LAN
I/F
H.323 Protocols





H.225: call control within H.323 net
RTP/RTCP used for audio/video streams
H.245: control channel to set up logical
channels
RAS: registration, admission control,
bandwidth management
RSVP – Resource Reservation Protocol:
allows user to request a specific amount of
bandwidth
Typical H.323 Stack
Multimedia H.323
Applications, User Interface
Data
Applications
V.150
T.120
Media Control
T.38
Audio
Video
Codecs
Codecs
G.711
H.261
G.723.1
H.263
G.729
H.264
..
..
Terminal Control and Management
H.225.0
RTCP
Call
H.245
Signaling
H.225.0
RAS
RTP
UDP
TCP
TCP/UDP
UDP
IP
TCP/UDP
TCP
UDP
Basic Call Setup Signaling H.225.0
Setup
Optional
Call Proceeding
Progress
Alerting
Connect
GW
GW
CONNECTED
Release
Complete
Call Setup Capture
TCP
Control Packets
No. Time
Source
Destination
Protocol Info
6 18.904189 192.168.0.149
192.168.0.143
TCP
1748 > 1720 [SYN] Seq=1739645016 Ack=0 Win=16384 Len=0
7 18.905196 192.168.0.143
192.168.0.149
TCP
1720 > 1748 [SYN, ACK] Seq=4252100644 Ack=1739645017 Win=17520 Len=0
8 18.905366 192.168.0.149
192.168.0.143
TCP
1748 > 1720 [ACK] Seq=1739645017 Ack=4252100645 Win=17520 Len=0
11 19.497846 192.168.0.149
192.168.0.143
H.225.0 CS: Setup-UUIE
12 19.769449 192.168.0.143
192.168.0.149
TCP
[Desegmented TCP]
13 20.099818 192.168.0.149
192.168.0.143
TCP
1748 > 1720 [ACK] Seq=1739645217 Ack=4252100649 Win=17516 Len=0
14 20.101044 192.168.0.143
192.168.0.149
H.225.0 CS: Alerting-UUIE
16 20.501086 192.168.0.149
192.168.0.143
TCP
1748 > 1720 [ACK] Seq=1739645217 Ack=4252100688 Win=17477 Len=0
20 29.091030 192.168.0.143
192.168.0.149
TCP
[Desegmented TCP]
21 29.329256 192.168.0.149
192.168.0.143
TCP
1748 > 1720 [ACK] Seq=1739645217 Ack=4252100692 Win=17473 Len=0
22 29.330385 192.168.0.143
192.168.0.149
H.225.0 CS: Connect-UUIE
23 29.400799 192.168.0.149
192.168.0.143
TCP
1749 > 1862 [SYN] Seq=1740980379 Ack=0 Win=16384 Len=0
24 29.401781 192.168.0.143
192.168.0.149
TCP
1862 > 1749 [SYN, ACK] Seq=4253464033 Ack=1740980380 Win=17520 Len=0
25 29.401944 192.168.0.149
192.168.0.143
TCP
1749 > 1862 [ACK] Seq=1740980380 Ack=4253464034 Win=17520 Len=0
26 29.405685 192.168.0.149
192.168.0.143
TCP
[Desegmented TCP]
27 29.453530 192.168.0.143
192.168.0.149
TCP
[Desegmented TCP]
28 29.453752 192.168.0.149
192.168.0.143
H.245 TerminalCapabilitySet MasterSlaveDetermination
29 29.455958 192.168.0.143
192.168.0.149
H.245 TerminalCapabilitySet MasterSlaveDetermination
30 29.465312 192.168.0.149
192.168.0.143
TCP
[Desegmented TCP]
31 29.471165 192.168.0.143
192.168.0.149
TCP
[Desegmented TCP]
32 29.471402 192.168.0.149
192.168.0.143
H.245 TerminalCapabilitySetAck MasterSlaveDeterminationAck
33 29.472271 192.168.0.143
192.168.0.149
H.245 TerminalCapabilitySetAck MasterSlaveDeterminationAck
34 29.678682 192.168.0.149
192.168.0.143
TCP
[Desegmented TCP]
35 29.679868 192.168.0.143
192.168.0.149
H.245 OpenLogicalChannel OpenLogicalChannel OpenLogicalChannel
43 30.532924 192.168.0.149
192.168.0.143
TCP
1749 > 1862 [ACK] Seq=1740980892 Ack=4253464654 Win=16900 Len=0
45 35.545028 192.168.0.143
192.168.0.149
RTCP Receiver Report
48 35.546773 192.168.0.149
192.168.0.143
RTCP Receiver Report
50 1239.290373 192.168.0.149
192.168.0.143
RSVP PATH Message. SESSION: IPv4, Destination 192.168.0.143, Protocol 17, Port 49608. SENDER
TEMPLATE: IPv4, Sender 192.168.0.149, Port 49608.
51 1239.322672 192.168.0.143
192.168.0.149
RSVP RESV Message. SESSION: IPv4, Destination 192.168.0.143, Protocol 17, Port 49608.
H.225.0 setup
Alerting
Connecting
Negotiating
Channel Usage
Requesting
Bandwidth
Data Transfer Capture
RTP video
H.263 Packet
No. Time
Source
Destination
Protocol Info
62 1240.429251 192.168.0.143
192.168.0.149
TCP
1862 > 1749 [ACK] Seq=4253464654 Ack=1740980896 Win=17004 Len=0
63 1240.429470 192.168.0.149
192.168.0.143
H.245 OpenLogicalChannelReject OpenLogicalChannelAck OpenLogicalChannelAck MiscellaneousCommand
MiscellaneousCommand OpenLogicalChannelConfirm
65 1240.622962 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12977, Time=3017250
66 1240.623218 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12978, Time=3017250
71 1240.854456 192.168.0.143
192.168.0.149
TCP
1862 > 1749 [ACK] Seq=4253464654 Ack=1740980980 Win=16920 Len=0
72 1240.854730 192.168.0.143
192.168.0.149
TCP
1503 > 1752 [ACK] Seq=4255085782 Ack=1742545885 Win=17315 Len=0
74 1240.915746 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12980, Time=3030750
75 1240.916004 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12981, Time=3030750
76 1240.916239 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12982, Time=3030750, Mark
87 1240.977683 192.168.0.149
192.168.0.143
TCP
1753 > 1503 [PSH, ACK] Seq=1742695460 Ack=4255248829 Win=17520 Len=25
88 1240.979358 192.168.0.143
192.168.0.149
TCP
1503 > 1753 [PSH, ACK] Seq=4255248829 Ack=1742695485 Win=17495 Len=21
89 1241.212546 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12983, Time=3044070
90 1241.212801 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12984, Time=3044070, Mark
91 1241.231672 192.168.0.149
192.168.0.143
TCP
1753 > 1503 [ACK] Seq=1742695485 Ack=4255248850 Win=17499 Len=0
92 1241.231775 192.168.0.149
192.168.0.143
TCP
1749 > 1862 [ACK] Seq=1740980980 Ack=4253464658 Win=16896 Len=0
93 1241.232617 192.168.0.143
192.168.0.149
H.245 MiscellaneousCommand
97 1241.364228 192.168.0.143
192.168.0.149
RTP
Payload type=ITU-T H.263, SSRC=4062428632, Seq=32093, Time=1885770, Mark
98 1241.366210 192.168.0.149
192.168.0.143
TCP
[Desegmented TCP]
99 1241.380190 192.168.0.149
192.168.0.143
TCP
1753 > 1503 [PSH, ACK] Seq=1742695485 Ack=4255248850 Win=17499 Len=268
100 1241.384497 192.168.0.143
192.168.0.149
TCP
1503 > 1753 [PSH, ACK] Seq=4255248850 Ack=1742695753 Win=17227 Len=106 Time=51984, Mark
163 1242.823618 192.168.0.143
192.168.0.149
RTP
Payload type=ITU-T G.723, SSRC=756814963, Seq=32091, Time=52704
164 1242.836785 192.168.0.149
192.168.0.143
TCP
1753 > 1503 [ACK] Seq=1742695794 Ack=4255249018 Win=17331 Len=0
165 1242.836872 192.168.0.149
192.168.0.143
TCP
1754 > 1503 [ACK] Seq=1742808026 Ack=4255332966 Win=17168 Len=0
166 1242.897739 192.168.0.143
192.168.0.149
RTP
Payload type=ITU-T G.723, SSRC=756814963, Seq=32092, Time=53424
167 1242.908675 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12996, Time=3120210
168 1242.908963 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12997, Time=3120210
173 1243.099425 192.168.0.143
192.168.0.149
RTP
Payload type=ITU-T H.263, SSRC=4062428632, Seq=32109, Time=1963890, Mark
174 1243.107713 192.168.0.143
192.168.0.149
RTP
Payload type=ITU-T G.723, SSRC=756814963, Seq=32093, Time=54144
175 1243.202816 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=12999, Time=3133620
176 1243.203076 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=13000, Time=3133620
177 1243.205246 192.168.0.149
192.168.0.143
RTP
Payload type=ITU-T H.263, SSRC=1488263488, Seq=13001, Time=3133620, Mark
More
Control
RTP
Audio
G.723
Media Gateway Control Protocols


Enable simple terminal equipment (i.e.
telephone) to connect to Internet for IP
telephone service
Two components:


Media Gateway: performs media format
conversion between telephone & Internet
Residential Gateway: interacts between
telephone and call agents in Internet


Call agents interact with SS7 signaling network to
setup calls
Call agents use Media Gateway Control Protocol