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nan

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nan

PoTs and IP Network

Internet

PBX(Private Branch

eXchange)

PSTN (Public Switch

Telephone Network)

PoTs (Plain Old Telephone System)

IP Network

Migration towardsIntegrated solution

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nan

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nan

Base rate

Sampler8000 times per

seconds)Once every 125 microSeconds

Analogue-to-digital converter(12-bits)

Compressor(u-Law/A-Law)

12-to-8-bits

Serialiser64 kbps

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nan

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ISDN, E1 and T1

64kbps(Data)

64kbps(Data)

16 kbps(Signal)

Base-rateISDN

64kbps(Data 1)

64kbps(Data 2)

64 kbps(Signal)

Primary-rate ISDN

(T1 PRI)

64kbps(Data 23)

64kbps(Data 1)

64kbps(Data 2)

64 kbps(Signal)

Primary-rate ISDN

(E1 PRI)

64kbps(Data 30)

Total rate: 160kbps

Total bit rate: 1.544 Mbps Total bit rate: 2.048 Mbps

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nan

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AVVID

AVVID: Architecture for Voice, Video and Integrated Data

Key focus:· Network Management· High availability· Security· QoS

Key metrics (Voice):· Necessary bandwidth· Acceptable delay· Acceptable jitter· Acceptable loss

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Voice:· Constant requirement for

bandwidth.· Delay sensitive.· Jitter sensitive.· Relatively error

insensitive

Traffic classification

Trafficcompression

PrioritisedQueues

CongestionAvoidanceMethods

Traffic shaping

QoS methods

Data:· Bursty bandwidth

requirement.· Delay insensitive· Jitter insensitive.· Error sensitive

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Bandwidth calculation

Voice:· Constant requirement for

bandwidth.· Delay sensitive.· Jitter sensitive.· Relatively error

insensitive

Ethernet(14 bytes)

IP(20 bytes)

UDP (8 bytes) RTP (12 bytes)

Voice payload[G.711 (64Kbps)]

160 Bytes


120 Bytes


40 Bytes

Total data frame size (G.711) = 14+20+8+12+160+4 = 218 bytes

Ethernet(4 bytes)

Packets generated by second (G.711) = 50 pps

Bandwidth required for each call (G.711) = 218x8x50 = 87.2kbps

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Providing power to the phone over Ethernet

WS-PWR-PANEL (Patch panel in-line power)

3524-PWR-XL (based on 3524XL switch)

4000-series switch withIn-line Power module

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nan

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Good design practices

AVVID: Architecture for Voice, Video and Integrated DataGood practice (Layer 2)· Separate VLANs for data and

voice.· STP features: PortFast,

UpLinkFast UDLD and Root Guard.

· 802.1P/802.1Q tagging.

Good pratice (Layer 3)· OSPF/EIGRP for fast

convergence.· Passive interfaces for access

layer so that there is no routing updates sent to them.

· HSRP/GLBP used for gateway redundancy.

Typical prioritization:1. Voice/video (highest priority)2. Transactional applications3. Data transfers (lowest priority)

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Delay, Jitter and Packet Loss

Delay (<60ms)

Transmissionsystem

Transmissionsystem

Jitter (<20ms)

Transmissionsystem

Packet lossError on line, or when congestion:Tail drop,Random early detection (RED)Weight RED

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nan

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Delays

Packetization

Serialization

PropagationProcessingQueuing

Processing

Packetization

Serialization

Processing

Fixed delay. Such as amount of time to encapsulate/de-capsulate and propagation delay.Variable delay. Such as queuing time and processing on the devices.

Issues for QoS:· Bandwidth.· Delay.· Jitter.· Packet loss.

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Jitter

Transmissionsystem

Jitter (<20ms)

JitterOverrun

Buffer cannot resize itself to handle changes in delay variation -> leads

to dropped packets

Jitter buffers- smooths-out

delays

JitterUnderrun

Variation in delays is too large, that the buffer cannot smooth-out

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nan

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QoS Methods

Classification. Sorts and classifies traffic.

Issues for QoS:· Bandwidth.· Delay.· Jitter.· Packet loss.

Marking. Adds tags to the packets/frames to classify/prioritize flow.

Forwarding. Switching traffic from one interface to another (CEF/fast switching)

Policing. Analyse bandwidth, jitter, delay, and packet loss, and determine whether to drop or break.

Queuing. Determines the queue that the packets should be placing for egress queuing.

Scheduling. Defines how the queues should be serviced … highest priority first, or round-robin?

Traffic shaping. Tries to smooth-out traffic flows to remove jitter, or restrict bandwidth usage.

Dropping. Defines which packets to drop, and when.

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IntServ and DiffServ

Best effortNo QoS.

First-in, first-outIntServ (Integrated Services)Connection reserved at start via RSVP for every connection.All the devices are enabled to support the connection.

Strength: Guaranteed QoS

Weakness: Not scaleable and requires extra bandwidth for RSVP.

DiffServ (Differentiated Services)Done of a hop-to-hop basis. Mark TOS field in IP header.

Strength: Easier to implement than IntServ and costs less.

Weakness: Best effort. Requires packet tagging.

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nan

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Classification and marking of

traffic

Queuing method

Conditioningtraffic

Marking options· Layer 2. CoS field in IEEE 802.1P frame. Values: 0

(Best effort), 1 (Medium), 2 (High), and so on. 3 bits.· Layer 3. TOS field in IP header for DiffServ. 6-bits

gives 64 levels. 2 bits used for congestion.

Classification methods· Policy-based routing. Route maps.· Priority and Custom Queuing – ACLs, ingress

interface, Layer 3 protocol and/or packet size.· Committed Access Rate (CAR). ACLs, DSCP,

QoS groups and rate limit ACLs.· All methods. Class maps.

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DiffServ values

Classification and marking of

traffic

Marking options· Layer 3. TOS field in IP header for DiffServ. 6-bits

gives 64 levels. 2 bits used for congestion.

P2 P1 P0 T2 T1 T0 CU1 CU0

· IP precedence—three bits (P2 to P0)

· Delay, Throughput and Reliability—three bits (T2 to T0)

· CU (Currently Unused)—two bits(CU1-CU0)

Original TOS field definition (RFC 791)

D5 D4 D3 D2 D1 D0 ECN ECN

· DSCP - six bits (DS5-DS0)· ECN (Explicit Congestion

Notification)- two bits

DiffServ TOS field definition (RFC 2474/2475)

Drop Class 1 Class 2 Class 3 Class 4

Low

001010 AF11 DSCP 10

010010 AF21 DSCP 18

011010 AF31 DSCP 26

100010 AF41 DSCP 34

Medium

001100 AF12 DSCP 12

010100 AF 22 DSCP 20

011100 AF32 DSCP 28

100100 AF42 DSCP 36

High

001110 AF13 DSCP 14

010110 AF23 DSCP 22

011110 AF33 DSCP 30

100110 AF43 DSCP 38

(confi g)# cl ass- map match- al l VOI P 1751- uut 1( confi g- cmap) # mat ch i p dscp ? <0- 63> Di ff er ent i at ed ser vi ces codepoi nt val ue af 11 Mat ch packet s wi t h AF11 dscp ( 001010) af 12 Mat ch packet s wi t h AF12 dscp ( 001100) af 13 Mat ch packet s wi t h AF13 dscp ( 001110) af 21 Mat ch packet s wi t h AF21 dscp ( 010010) af 22 Mat ch packet s wi t h AF22 dscp ( 010100) af 23 Mat ch packet s wi t h AF23 dscp ( 010110) af 31 Mat ch packet s wi t h AF31 dscp ( 011010) af 32 Mat ch packet s wi t h AF32 dscp ( 011100) af 33 Mat ch packet s wi t h AF33 dscp ( 011110) af 41 Mat ch packet s wi t h AF41 dscp ( 100010) af 42 Mat ch packet s wi t h AF42 dscp ( 100100) af 43 Mat ch packet s wi t h AF43 dscp ( 100110) cs1 Mat ch packet s wi t h CS1( pr ecedence 1) dscp ( 001000) cs2 Mat ch packet s wi t h CS2( pr ecedence 2) dscp ( 010000) cs3 Mat ch packet s wi t h CS3( pr ecedence 3) dscp ( 011000) cs4 Mat ch packet s wi t h CS4( pr ecedence 4) dscp ( 100000) cs5 Mat ch packet s wi t h CS5( pr ecedence 5) dscp ( 101000) cs6 Mat ch packet s wi t h CS6( pr ecedence 6) dscp ( 110000) cs7 Mat ch packet s wi t h CS7( pr ecedence 7) dscp ( 111000) def aul t Mat ch packet s wi t h def aul t dscp ( 000000) ef Mat ch packet s wi t h EF dscp ( 101110) (confi g- cmap)# match i p dscp af 31

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Queuing methods

Class-based Weighted Fair Queuing (CB-WFQ)Decides queuing method automatically determines what should go into higher and lower priority queues

Low Latency Queuing (LLQ)Checks the classification of the egress traffic and if the priority is high, it is process first, otherwise it uses a class-based weighted-fair queue

Priority Queuing (PQ)Queuing method which has four queues of high, medium, normal and low priorities. Always empty the highest priority queue first.

Weighted Fair Queuing (WFQ)Queuing method that examines the traffic flow, such as for source and destination addresses, to determine the type of queuing.

Weighted Round-Robin Queuing (WRRQ)Queuing method which priorities based on the IP precedence value, but still gives low priority a chance.

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Congestion Avoidance

Packet

Egress buffer

Packet

Packet

Packet

Interface

Buffer is full. Next packets will be dropped unless the buffer is emptied

RouteProcessor

Tail Dropping

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nan

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RED and WRED

Packet

Egress buffer

Packet

Packet

Packet

InterfaceRoute

Processor

RED and WRED

RandomEarly

Detection

Randomlydelete

Weighted RED. Uses CoS value to drop backs.

Threshold 1 (50%)CoS=0,1Random drop.

Threshold 2 (80%)CoS=2,3Random drop.

CoS 2,3 has higher priority.

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Example of Modular QoS

( confi g) # access- l i st 1 per mi t 192. 168. 0. 0 0. 0. 0. 255( confi g) # cl ass- map cl ass1 ( confi g- cmap) # mat ch access- gr oup 101 ( confi g- cmap) # exi t

( confi g) # pol i cy- map pol i cy1( confi g- pmap) # cl ass cl ass1 ( confi g- pmap- c) # bandwi dt h 3000 ( confi g- pmap- c) # queue- l i mi t 30 ( confi g- pmap- c) # set dscp AF12( confi g- pmap) # exi t

( confi g) # i nt er f ace e1( confi g- i f ) # ser vi ce- pol i cy out put pol i cy1 ( confi g- i f ) # exi t

Class-mapClassification of

traffic

Traffic policyMarking of

traffic, policing and queue type

Apply policy

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Class-mapDefine traffic

characteristics

Policy-mapDefine the

policy for the traffic

Service-policyApply the policy

First define Class Map(config)# access-list 108 permit ip 162.78.102.0 0.0.255.255 247.226.90.0 0.0.255.255(config)# class-map tayside(config-cmap)# ?QoS class-map configuration commands: description Class-Map description exit Exit from QoS class-map configuration mode match classification criteria no Negate or set default values of a command rename Rename this class-map(config-cmap)# match ? access-group Access group any Any packets class-map Class map destination-address Destination address input-interface Select an input interface to match ip IP specific values mpls Multi Protocol Label Switching specific values not Negate this match result protocol Protocol source-address Source address vlan VLANs to match(config-cmap)# match access-group 108(config-cmap)# exit

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Next define Policy map

(config)# policy-map ankle(config-pmap)# ?QoS policy-map configuration commands: class policy criteria description Policy-Map description exit Exit from QoS policy-map configuration mode no Negate or set default values of a command rename Rename this policy-map(config-pmap)# class tayside(config-pmap-c)# ?QoS policy-map class configuration commands: bandwidth Bandwidth exit Exit from QoS class action configuration mode no Negate or set default values of a command trust Set trust value for the class <cr> police Police set Set QoS values(config-pmap-c)# bandwidth 128(config-pmap-c)# queue-limit 21(config-pmap-c)# exit(config-pmap)# exit


characteristics




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Finally apply the policy map

(config)# int fa0/1(config-if)# service-policy ? history Keep history of QoS metrics input Assign policy-map to the input of an interface output Assign policy-map to the output of an interface(config-if)# service-policy output ? WORD policy-map name(config-if)# service-policy output ankle


characteristics




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Priority Queuing (PQ)

High

Medium

Normal

Low

(confi g)# pri ori ty- l i st 1 qUeue- l i mi t 20 40 60 80(confi g)# pri ori ty- l i st 1 protocol http hi gh(confi g)# pri ori ty- l i st 1 protocol i px l ow(confi g)# i nt seri al 0(confi g- i f )# pri ori ty- group 1(confi g- i f )# exi t(confi g)# Exi t# show pri ori ty queui ng

Priority Queuing (PQ)

Packet

High priority queue is always serviced first, followed by medium,

then by normal, and then by low

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PQ

(config)# priority-list ? <1-16> Priority list number(config)# priority-list 1 ? default Set priority queue for unspecified datagrams interface Establish priorities for packets from a named interface protocol priority queueing by protocol queue-limit Set queue limits for priority queues(config)# int fa0/1(config)# priority-list 1 q ? <0-32767> High limit(config)# priority-list 1 q 20 ? <0-32767> Medium limit(config)# priority-list 1 q 20 40 ? <0-32767> Normal limit(config)# priority-list 1 q 20 40 60 ? <0-32767> Lower limit(config)# priority-list 1 q 20 40 60 80 ? <cr>(config)# priority-list 1 q 20 40 60 80

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PQ(config)# prio 1 p ? aarp AppleTalk ARP appletalk AppleTalk arp IP ARP bridge Bridging bstun Block Serial Tunnel cdp Cisco Discovery Protocol clns ISO CLNS clns_es ISO CLNS End System clns_is ISO CLNS Intermediate System cmns ISO CMNS compressedtcp Compressed TCP (VJ) decnet DECnet decnet_node DECnet Node decnet_router-l1 DECnet Router L1 decnet_router-l2 DECnet Router L2 dlsw Data Link Switching (Direct encapsulation only) http HTTP ip IP ipv6 IPV6 ipx Novell IPX llc2 llc2 pad PAD links pppoe PPP over Ethernet qllc qllc protocol rsrb Remote Source-Route Bridging snapshot Snapshot routing support stun Serial Tunnel

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PQ(config)# priority-list 1 protocol http ? high medium normal low(config)# priority-list 1 protocol http high(config)# priority-list 1 protocol ipx low(config)# int serial0(config-if)# prority-group 1

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Custom Queuing (CQ)

1

2

16

(confi g)# queue- l i st 1 protocol i p 1(confi g)# queue- l i st 1 protocol cdp 2(confi g)# queue- l i st 1 queue 1 l i mi t 40(confi g)# queue- l i st 1 queue 2 l i mi t 20(confi g)# i nt f a0/ 1(confi g- i f )# Custom- queue- l i st 1

Custom Queuing (CQ)

Packet

CQ can use up to 16 queues in a round-robin

manner.

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CQ(config)# queue-list ? <1-16> Queue list number

(config)# queue-list 1 ? default Set custom queue for unspecified datagrams interface Establish priorities for packets from a named interface lowest-custom Set lowest number of queue to be treated as custom protocol priority queueing by protocol queue Configure parameters for a particular queue stun Establish priorities for stun packets(config)# queue-list 1 protocol ? arp IP ARP bridge Bridging bstun Block Serial Tunnel cdp Cisco Discovery Protocol compressedtcp Compressed TCP dlsw Data Link Switching (Direct encapsulation only) ip IP ipv6 IPV6 llc2 llc2 pad PAD links pppoe PPP over Ethernet qllc qllc protocol rsrb Remote Source-Route Bridging snapshot Snapshot routing support stun Serial Tunnel

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CQ(config)# queue-list 1 protocol ip ? <0-16> queue number

(config)# queue-list 1 protocol ip 1 ? gt Classify packets greater than a specified size lt Classify packets less than a specified size <cr>(config)# queue-list 1 protocol ip 1

(config)# que 1 queue ? <0-16> queue number

(config)# que 1 q 1 ? byte-count Specify size in bytes of a particular queue limit Set queue entry limit of a particular queue

(config)# que 1 q 1 limit ? <0-32767> number of queue entries

(config)# que 1 q 1 l 40 ? byte-count Specify size in bytes of a particular queue <cr>(config)# que 1 q 1 l 40(config)# int fa0/1(config-if)# custom-queue-list 1

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WRRQ(config-if)# wrr-queue bandwidth ? <1-65536> enter bandwidth weight for qid 1(config-if)# wrr-queue bandwidth 3 ? <1-65536> enter bandwidth weight for qid 2(config-if)# wrr-queue bandwidth 3 8 ? <1-65536> enter bandwidth weight for qid 3(config-if)# wrr-queue bandwidth 3 8 10 ? <1-65536> enter bandwidth weight for qid 4(config-if)# wrr-queue bandwidth 3 8 10 12

In this case the bandwidth is:

Queue 1: 3/(3+8+10+12) = 9.1%Queue 2: 3/(3+8+10+12) = 24.2%Queue 3: 3/(3+8+10+12) = 30.3%Queue 4: 3/(3+8+10+12) = 36.4%

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WRRQ(config-if)# wrr-queue cos-map ? <1-4> enter cos-map queue id(config-if)# wrr-queue cos-map 1 ? <0-7> 8 cos values separated by spaces(config-if)# wrr-queue cos-map 3 4 5

(config-if)# wrr-queue cos-map 1 0 1 2 4 (config-if)# wrr-queue cos-map 3 4 5

Queue 1 has CoS of 0, 1, 2 and 4 allocated to itQueue 3 has CoS of 4 and 5 allocated to it.

(config-if)# wrr-queue random-detect 1 max-threshold 50 100 (config-if)# wrr-queue random-detect 3 max-threshold 80 100

Queue 1 has a min threshold of 50% and a max of 100%Queue 3 has a min threshold of 80% and a max of 100%

To assign DSCP values to queues:

(config-if)# wrr-queue dscp-map 1 0 1 2 3 4 5 6 7 (config-if)# wrr-queue dscp-map 1 8 9 (config-if)# wrr-queue dscp-map 2 10 11 12 13 14

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nan

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nan

SPAN

(confi g)# moni tor sessi on 1 source i nterface fa0/ 1 - 2 rx(confi g)# moni tor sessi on 1 desti nati on i nterface fa0/ 14

All the received traffic from FA0/1 and FA0/2 are sent to this node

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Remote SPAN (RSPAN)

(confi g)# i nt vl an 10(confi g- vl an)# remote- span(confi g- vl an)# exi t(confi g)# moni tor sessi on 1 source i nterface fa0/ 1 - 2 rx(confi g)# moni tor sessi on 1 desti nati on remote vl an 10

All the received traffic from FA0/1 and FA0/2 are sent to a remote

station

(confi g)# moni tor sessi on 1 remote vl an 10(confi g)# moni tor sessi on 1 desti nati on i nterface fa0/ 14

pots and ip network

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