Download AVVID QoS Infrastructure Design

QOS For IP Video
Conference
Albert Garcia
[email protected]
System Engineer, Cisco Systems
11/14/2001
© 2000, Cisco Systems, Inc.
Cisco Confidential
1
Agenda
• QOS Overview
• Classifications
• QOS Design
• H.323 Gatekeeper
© 2000, Cisco Systems, Inc.
2
Why QoS?
Larger Input
i.e. GE
More Inputs
Smaller Output
i.e. 10/100
Fewer Outputs
No matter how high capacity the backplane is…
No matter what the PPS rating is…
No matter if it’s the fastest switch ever…
Congestion is present in ALL Networks
So QoS will be required..
So lets look at just what QoS is….
© 2000, Cisco Systems, Inc.
3
Campus QoS
Buffer Management and Multiple Queues
TX
TX
TX
Si
• Output buffers can reach
100% in Campus networks
Data
• When an output buffer
congests, dropped packets
occur at the ingress
interfaces
Data
• QoS required when there is a
possibility of congestion in
buffers
• Multiple Queues are the only
way to “Guarantee” Voice
Quality
© 2000, Cisco Systems, Inc.
TX TX
Queue
assignment
based on
Layer2/3
classification
TX
Catalyst Switch
RX
RX
To Core
TX
Data
RX
Video
RX
Video put into
“delay and
drop”
sensitive
queue
Queue
scheduling via
Round Robin,
Weighted RR
or PQ’ing; HW
dependent
4
What is QoS?
Policing
(Rate Limiting)
Rewriting
Congestion Management
Scheduling
© 2000, Cisco Systems, Inc.
Classification
5
3 Steps for CoS/QoS Implementation
Classification – Marking the packet with a specific
priority denoting a requirement for special service
from the network.
Scheduling – Assigning packets to one of multiple
queues (based on Classification) for expedited
treatment through the network.
Provisioning – Accurately calculating the required
bandwidth for all application and element overhead.
© 2000, Cisco Systems, Inc.
6
Classification
© 2000, Cisco Systems, Inc.
Cisco Confidential
7
Layer 2 and 3 Traffic
Classification
Layer 2
802.1Q/p
PREAM.
SFD
DA
TAG
4 Bytes
Typ
e
SA
PT
DATA
FCS
Three Bits Used for CoS
(802.1D User Priority)
CFI
PRI
VLAN ID
Layer 3
IPV4
Version
Length
7
ToS
1 Byte
6
Len
5
ID
Offset
4
TTL
3
Proto
FCS
2
1
IP-SA
IP-DA
Data
0
Unused Bits;
Flow Control
for DSCP
DSCP
Standard IPV4: Three MSB Called IP Precedence
(DiffServ May Use Six D.S. Bits Plus Two for Flow Control)
IP Precedence
© 2000, Cisco Systems, Inc.
8
CoS in 802.1Q (802.1p)
802.1p
6
Destination Address
6
Source Address
2
EtherType = TPID
2
Tag Control Information
2
MAC Length/Type
MAC DATA
PAD
4
© 2000, Cisco Systems, Inc.
FCS
3
1
User
Priority
CFI
VID (VLAN ID) —12 Bits
Used in:
• IEEE 802.3ac (VLAN Tag
Task Force)
• IEEE 802.1Q
• IEEE 802.1p
9
Type of Service (ToS)
How is Priority assigned to an IP Packet?
IPV4 Header
Version ToS
Len
Length 1 Byte
ID
Flags/
TTL Proto FCS IP-SA IP-DA Data
offset
Type of Service is a 1 Byte Field in the IPV4 Header
Used to indicate service to be applied to IP Packet
© 2000, Cisco Systems, Inc.
10
IP Precedence
IPV4 Header
contains ToS Byte
which equals 8
bits of which 3
are used for
priority
Precedence
111 Network Control
110 Internetwork Ctl
101 Critical
100 Flash Override
011 Flash
010 Immediate
001 Priority
000 Routine
© 2000, Cisco Systems, Inc.
Version ToS
Len …rest of the header…………….
Length 1 Byte
1
0
1
0
0
0
0
0
TOS = 10100000 = 160
P
P
P
D
T
R
M
R
IP Precedence = 101 = 5
Delay
Throughput
Reliability
Monetary
Cost
Reserved
0 Normal
1 Minimize
0 Normal
1 Maximize
0 Normal
1 Maximize
0 Normal
1 Minimize
*ALWAYS* set
to zero
11
Differentiated Services Code Point
(DSCP)
IPV4 Header
contains ToS Byte
which equals 8
bits of which 6
are used for
DSCP
1
Version ToS
Len
Length 1 Byte
0
1
0
1
0
…………………….
0
0
TOS = 10101000 = 168
DSCP = 101010 = 42
DSCP can yield up to 64 different levels of Priority I.e. 2 ^^8
The Catalyst 6K assigns an internal DSCP header to a frame as it transits
the switch (not to be confused with the actual DSCP)
This value is derived from an existing CoS/ToS value and is used to rewrite
the CoS/ToS on egress
Refer to RFC 2474 (Definition of the Differentiated
Services Field (DS Field) in the IPv4 and IPv6 Headers).
© 2000, Cisco Systems, Inc.
12
DiffServ Behaviors
DiffServ Code Points
(DSCP)
Per-Hop Behaviours (PHB)
Expedited
Forwarding
EF
Assured
Forwarding
Low Drop
Pref
Med Drop
Pref
High Drop
Pref
Class 1
AF11
AF12
AF13
001010 001100 001110
Class 2
AF21
AF22
AF23
010010 010100 010110
Class 3
AF31
AF32
AF33
011010 011100 011110
Class 4
AF41
AF42
AF43
100010 100100 100110
Best
Effort
© 2000, Cisco Systems, Inc.
101110
000000
13
Class of Service (CoS)
IP Header
Ethernet
Header
Data
Data
IP Priority is hidden when encapsulated
By Ethernet Frame
CoS bits in Ethernet header provide
priority
ToS bits can be
mapped to CoS bits
and vice versa
Class of Service bits exist in an ISL Header and
An 802.1Q Header
© 2000, Cisco Systems, Inc.
14
Mappings
You can map whatever to whatever
CoS
0
1
2
3
4
5
6
7
© 2000, Cisco Systems, Inc.
DSCP
0-7
8-15
16-23
24-31
32-39
40-47
48-55
56-63
IP Precedence
0
1
2
3
4
5
6
7
15
Cisco AVVID Classification
Voice with CallManager
• Voice
VoIP Control Channels
H.323 = TCP 1720, 11xxx (RAS = TCP 1719)
Skinny = TCP 2000-2002
ICCP = TCP 8001-8002
MGCP = UDP 2427, TCP 2428
CoS = 3, IP Prec = 3, DSCP = AF31 (26)
VoIP Bearer Channels
UDP 16384-32767
CoS = 5, IP Prec = 5, DSCP = EF (46)
© 2000, Cisco Systems, Inc.
16
Cisco AVVID Classification, Cont.
Video Classification
• Video
Video Control Channels
H.323 = TCP 1720, 11xxx (RAS = TCP 1719)
CoS = 3, IP Prec = 3, DSCP = AF31 (26)
Video Bearer Channels
UDP 16384-32767
CoS = 4, IP Prec = 4, DSCP = AF41 (42)
© 2000, Cisco Systems, Inc.
17
Cisco AVVID Classification, Cont.
Data Application Classification
• Data
Some data applications may need special handling from
the network
This can be for business, technical or Layer 8 reasons
CoS = 0-2, IP Prec = 0-2, DSCP = 0-23
• Recommendations
Only classify when necessary
Modifying WRED thresholds may be required to
insure performance
For a CoS/ToS = 2 applications, configure Queue #1’s
2nd Threshold (CoS/ToS = 2) to drop at 95% instead of
50%
© 2000, Cisco Systems, Inc.
18
QOS Design
© 2000, Cisco Systems, Inc.
Cisco Confidential
19
Campus QoS
WAN
All incoming
video from WAN
should be
classified as
DSCP=AF41
TX
NJ Edge
All incoming IP
Video from NJ
Edge should
already be tagged
as DSCP=AF41
from NJ Edge
Colleges
© 2000, Cisco Systems, Inc.
TX
Use LLQ on
Campus router
WAN. Use modCLI for L3 -> L2
scheduling on the
Ethernet interface
12.1(5)T
Gatekeeper for
Admission
Control and dial
plan
TX
TX
Branch Ethernet
switches with
multiple queuing
based on CoS on
all interfaces
Classify all IP
Video traffic
CoS=4
All Data traffic
CoS=0
20
Sources of Trouble for QOS
Provisioning
Nothing is Free - Especially on low speed links - Engineer the network for Data,
Voice, and Video
Voice
Video
Voice/Video
Control
Data
Routing
etc
0.75 x Link Capacity
Link Capacity
Link Capacity = (Min BW for Voice + Min BW for Video + Min BW for Data) / 0.75
© 2000, Cisco Systems, Inc.
21
QoS is Needed to Minimize Packet Loss,
Delay and Delay Variation
Where QoS is Needed
Central Campus
Remote Branch
Si
WAN
Si
QoS - Campus Access QoS - Campus Distrib
Speed and Duplex
settings
Classification/Trust
on Video Endpoint
and Access switch
Multiple queues on
Access ports
© 2000, Cisco Systems, Inc.
Layer 3 Policing
Multiple queues on all
ports; Priority
Queuing for VoIP
WRED within Data
queue for Congestion
Management
QoS - WAN
Low-Latency
Queuing
Link Fragmentation
and Interleave
Bandwidth
Provisioning
Admission Control
QoS - Branch
Classification and
Trust Boundaries on
IP Video endpoints ,
Access Layer switch
and router
Multiple queues on
Access ports
22
H.323 Gatekeeper
© 2000, Cisco Systems, Inc.
Cisco Confidential
23
Multimedia Conference Manager
Jack
Multimedia
Conference Manager
MCM
Cisco 2500, 3810,
2600, 3600, 7200
Yvette
Kim
IP
Ms. Gomez
Mike
ISDN
Cisco IOS software feature that functions as a
high-performance H.323 gatekeeper and proxy
© 2000, Cisco Systems, Inc.
24
Multi Zone WAN Model
Zone 2
Zone 1
H.323 Terminals
H.323 Terminals
Gatekeeper
GK
GK
QoS Enabled
IP WAN
MCU
GW
H.323 Terminals
GK
Gateway
MCU
MCU
ISDN
H.320
Video Unit
MCU
Zone 3
© 2000, Cisco Systems, Inc.
25
NJ Edge Gatekeeper Design
NJ Edge POP
Directory
Gatekeeper
ATM
Gatekeeper/proxy
3540 MCU
3540 MCU
Campus A
© 2000, Cisco Systems, Inc.
Gatekeeper/proxy
Campus B
26
Features and Benefits of
Cisco Gatekeeper
Multimedia Conference Manager Features
• Allows the implementation of QoS policies to guarantee
bandwidth availability and manage bandwidth usage
• Security
• Address resolution and call routing
• User authentication and call accounting
Multimedia Conference Manager Benefits
• Provides gatekeeper, proxy, and routing functions on a single
hardware/software platform
• Accommodates small to large H.323 network deployments
according to router platforms
• Is interoperable with H.323v1 and v2-compliant endpoints
• Uses e-mail address instead of IP addresses
© 2000, Cisco Systems, Inc.
27
Call Admission Control (CAC)
Bandwidth Management
Zone A
Zone C
3
1
GK
GK
Zone B
2
IOS Bandwidth Commands
Interzone—Bandwidth from a local or default zone to all
other local zones or remote zones(1 and 3
Remote—Bandwidth to and from all local zones to all
remote zones – BETWEEN PHYSICAL
GATEKEEPERS (3 only)
Total—Total bandwidth in a zone (1+2+3)
Session—Bandwidth per session in a zone
© 2000, Cisco Systems, Inc.
28
Cisco Router IOS MCM
MCM Performs
Two Functions
• MCM gatekeeper
Address resolution
User authorization
Gatekeeper
Zone bandwidth management
• MCM proxy
MCM
Security (address translation)
QoS for non QoS capable
hosts and gateways,
Proxy
© 2000, Cisco Systems, Inc.
Application specific routing
29
Cisco MCM
Proxy Security
218.6.5.1
2
192.7.6.1
Network
H.323
Room
System
H.323
Clients
H.323
Room
System
MCM H.323
1 Gatekeeper/Proxy
3
H.323
Clients
10.1.1.10
10.3.1.12
© 2000, Cisco Systems, Inc.
30
Key Differentiators of MCM
Multimedia Conference Manager Differentiators
from other Vendors
• Unique in offering proxy services as well as
gatekeeper services
• Combines gatekeeper/proxy services with routing
capabilities on a single hardware platform
• Supports a multiservice IP networking environment
for data, voice, and H.323 videoconferencing on
a common software base
• Offers scalability through a wide range of Cisco
router platforms
• Offers excellent price/performance ratio for small
and large H.323 network deployments
© 2000, Cisco Systems, Inc.
31
© 2000, Cisco Systems, Inc.
32