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IP QoS Principles Theory and Practice Dimitrios Kalogeras.

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1 IP QoS Principles Theory and Practice Dimitrios Kalogeras

2 A Bit of History The Internet, originally designed for U. S. government use, offered only one service level: Best Effort. –No guarantees of transit time or delivery –Rudimentary prioritization was available, but it was rarely used. Commercialization began in early 1990’s –Private (intranet) networks using Internet technology appeared. –Commercial users began paying directly for Internet use. –Commerce sites tried to attract customers by using graphics. –Industry used the Internet and intranets for internal, shared communications that combined previously-separate, specialized networks -- each with its own specific technical requirements. –New technologies (voice over the Internet, etc.) appeared, designed to capitalize on inexpensive Internet technologies.

3 The Demands on Modern Networks Network flexibility is becoming central to enterprise strategy –Rapidly-changing business functions no longer carried out in stable ways, in unchanging locations, or for long time-periods –Network-enabled applications often crucial for meeting new market opportunities, but there’s no time to custom-build a network Traffic is bursty Interactive voice, video applications have stringent bandwidth and latency demands Multiple application networks are being combined into consolidated corporate utility networks –Bandwidth contention as critical transaction traffic is squeezed by web browsing, file transfers, or other low-priority or bulk traffic –Latency problems as interactive voice and video are squeezed by transaction, web browsing, file transfer, and bulk traffic

4 Definitions Quality of Service (QoS) classifies network traffic and then ensures that some of it receives special handling. –May track each individual dataflow (sender:receiver) separately. –May include attempts to provide better error rates, lower network transit time (latency), and decreased latency variation (jitter). Differentiated Class of Service (CoS) is a simpler alternative to QoS. –Doesn't try to distinguish among individual dataflows; instead, uses simpler methods to classify packets into one of a few categories. –All packets within a particular category are then handled in the same way, with the same quality parameters. Policy-Based Networking provides end-to-end control. –The rules for access and for management of network resources are stored as policies and are managed by a policy server.

5 5 QoS Background Video Streaming Services Video Conferencing VoIP Legacy SNA / DLSw QoS development inspired by new types of applications in IP environment:

6 6 QoS Architecture Models Best Effort Service Integrated Service Differentiated Service

7 7 Best Effort Service What exactly IP does: All packets treated equally Unpredictable bandwidth Unpredictable delay and jitter

8 8 IntServ (RFC1633)

9 9 DiffServ (RFC2474/2475)

10 10 QoS Architecture Components Classification Coloring Admission Control Traffic Shaping/Policing Congestion Management Congestion Avoidance Signaling

11 Statistical Behavior: Random Arrival In random arrival, the time that each packet arrives is completely independent of the time that any other packet arrives. –If the true situation is that arrivals tend to be evenly spaced, then random arrival calculations will overestimate the queuing delay. –If the true situation is that arrivals are bunched in groups (typical of data flows, such as packets and acknowledgements), then random arrival calculations will underestimate the queuing delay. Our intuition is usually misleading when we think of random processes. –We tend to assume that queue size increases linearly as the number of customers increases. –But, with random arrival, there is a drastic increase in queue size as the customer arrival rate approaches 80% of the theoretical server capacity. There’s no way to store the capacity that is unused by late customers, but early customers increase the queue.

12 Random Arrival and Intuition The surprising increase in queue length is best shown by a graph:

13 Random Arrival vs. Self-Similar Although random arrival is very convenient mathematically (it’s relatively simple to do random arrival calculations), it has been shown that much data traffic is self-similar. –Ethernet and Internet traffic flows, in particular, are self-similar. –The rate of initial connections is still random, however. Self-similar traffic shows the same pattern regardless of changes in scale. –Fractal geometry (e.g., a coastline) is an example. Self-similar traffic has a heavy tail. –The probabilities of extremely large values (e.g., file lengths of a gigabyte or more) don’t decrease as rapidly, as they would with random distributions of file lengths. –This matches real data traffic behaviors. Long file downloads mixed with short acknowledgements Compressed video with action scenes mixed with static scenes

14 14 Traffic Classification Most fundamental QoS building block The component of a QoS feature that recognizes and distinguishes between different traffic streams Without classification, all packets are treated the same

15 15 Traffic Classification/ Admission Control Issues Always performed at the network perimeter Makes traffic conform to the internal network policy Marks packets with special flags (colors) Colors used afterwards inside the network for QoS management

16 16 Classification/ Admission Control Scheme Classifier Meter Marker Shaper/ Policer Packet Admitted Dropped

17 17 Classification Criteria IP header fields TCP/UDP header fields Routing information Packet Content (NBAR) i.e. HTTP, HTTPS, FTP, Napster etc.

18 18 Traffic Coloring Options IP Precedence DSCP QoS Group 802.1p CoS ATM CLP Frame Relay DE

19 19 Type-of-Service (RFC791) VersionLengthTotal Length PrecedenceUnusedDTR 01 D Normal DelayLow Delay T Normal ThroughputHigh Throughput R Normal ReliabilityHigh Reliability ToS Field …

20 20 IP Precedence Values 111Network Control 110Internetwork Control 101Critical 100Flash Override 011Flash 010Immediate 001Priority 000Routine

21 21 DSCP Diffserv Code Point DSCP (6 bits)Unused Class 1Class 2Class 3Class 4 Low Drop Precedence Medium Drop Precedence High Drop Precedence

22 22 Classification mechanisms MQC ( Modular Qos Command Line Interface) CAR ( Commited Access Rate)

23 23 Modular QoS CLI Modular QoS CLI (MQC) Command syntax introduced in 12.0(5)T Reduces configuration steps and time Uniform CLI across all main Cisco IOS-based platforms Uniform CLI structure for all QoS features

24 24 Basic MQC Commands class-map [match-any | match-all] class-name router(config)# 1. Create Class Map - a traffic class ( match access list, input interface, IP Prec, DSCP, protocol (NBAR) src/dst MAC address, mpls exp). policy-map policy-map-name router(config)# 2. Create Policy Map (Service Policy) - Associate a class map with one or more QoS policies (bandwidth, police, queue- limit, random detect, shape, set prec, set DSCP, set mpls exp). service-policy {input | output} policy-map-name router(config-if)# 3. Attach Service Policy - Associate the policy map with an input or output interface.

25 25 1. Create Class Map – defines traffic selection criteria Router(config)# class-map class1 Router(config-cmap)# match ip precedence 5 Router(config-cmap)# exit Router(config)# policy-map policy1 Router(config-pmap)# class class1 Router(config-pmap-c)# set mpls experimental 5 Router(config-pmap-c)# bandwidth 3000 Router(config-pmap-c)# queue-limit 30 Router(config-pmap)# exit Router(config)# interface e1/1 Router(config-if)# service-policy output policy1 Router(config-if)# exit 2. Create Policy Map- associates classes with actions 3. Attach Service Policy – enforces policy to interfaces Basic MQC Commands

26 26 Classification Configuring Sample class-map match-all premium match access-group name premium ! class-map match-any trash match protocol napster match protocol fasttrack ! policy-map classify class premium set ip precedence priority class trash police conform-action set-prec-transmit 1 excess-action drop ! ip access-list extended premium permit tcp host any eq telnet ! interface serial 2/1 ip unnumbered loopback 0 service-policy input classify Traffic class definitions QoS policy definition QoS Policy attached to interface ACL definition MQC based IOS 12.1(5)T

27 27 Classification Configuring Sample ip cef ! interface serial 2/1 ip unnumbered loopback 0 rate-limit input access-group conform-action set-prec-transmit 1 exceed-action set-prec-transmit 0 ! access-list 100 permit tcp host any eq http CAR definition ACL definition CAR based

28 28 Classification Configuring Sample route-map classify permit 10 match ip address 100 set ip precedence flash ! route-map classify permit 20 match ip next-hop 1 set ip precedence priority ! interface serial 2/1 ip unnumbered loopback 0 ip policy route-map classify ! access-list 1 permit access-list 100 permit tcp host any eq http Route-map definitions ACL definitions Route-map based Route-map attached to interface

29 29 Shaping/Policing Used to assign more predictive behavior to traffic Uses Token Bucket model

30 30 Token Bucket Model Token Bucket main parameters: Token Arrival Rate - v Bucket Depth - Bc Time Interval – tc Link Capacity - C Overflow Tokens Tokens Incoming packets Conform Exceed Bc v C Token Bucket characterizes traffic source tc = Bc/v

31 31 Token Bucket Model Bucket is being filled with tokens at a rate v token/sec. When bucket is full all the excess tokens are discarded. When packet of size L arrives, bucket is checked for availability of corresponding amount of tokens. If several packets arrive back-to-back and there are sufficient tokens to serve them all, they are accepted at peak rate (usually physical link speed). If enough tokens available, packet is optionally colored and accepted to the network and corresponding amount of tokens is subtracted from the bucket. If not enough tokens, special action on packet is performed.

32 32 Token Bucket Model Actions performed on nonconforming packets: Dropped (Policing) Delayed in queue either FIFO or WFQ (Shaping) Colored/Recolored

33 33 Token Bucket Model Bucket depth variation effect: Bc = 0Constant Bit Rate (CBR) Bc  No Regulation Bucket depth is characteristic of traffic burstiness Maximum number of bytes transmitted over period of time  t: A(  t) max = Bc+v·  t

34 34 Excess Burst (Be) Cisco Implementation GTS ( Generic Traffic Shaping) If during previous tc n-1 interval bucket Bc was not depleted (there is no congestion), in the next interval tc n Bc+Be bytes are available for burst. In frame relay implementations packets admitted via Be tokens are marked with DE bit.

35 35 Excess Burst (Be) Cisco Implementation CBTS (Class Based Traffic Shaping) allows higher throughput in uncongested environment up to peak rate calculated as v Peak = v CIR (1+Be/Bc) Peak rate can be set up manually.

36 36 Excess Burst (Be) Cisco Implementation CAR allows RED like behavior: traffic fitting into Bc always conforms traffic fitting into Be conforms with probability proportional to amount of tokens left in the bucket traffic not fitting into Be always exceeds CAR uses the following parameters:  t – time period since the last packet arrival Current Debt (D cur ) – Amount of debt during current time interval Compound Debt (D comp ) – Sum of all D cur since the last drop Actual Debt (D act ) – Amount of tokens currently borrowed

37 37 Excess Burst (Be) Cisco Implementation CAR Algorithm Packet of length L arrived Bc cur – L > 0 Conform Action Y D cur = L - Bc cur Bc cur = 0 D comp = D comp + D cur D act = D act + D cur +v·  t N D act > Be Y N Exceed Action D comp > Be Y N D comp = 0 Bc cur = Bc cur – L

38 38 Shaping Configuration Sample interface serial 2/1 ip unnumbered loopback 0 traffic-shape rate ! interface serial 2/2 ip unnumbered loopback 0 traffic-shape group ! access-list 100 permit tcp host any eq http GTS Based Shaper Definitions ACL definition Shaper can be only used to control egress traffic flow!

39 39 Policing Configuration Sample ip cef interface serial 2/1 ip unnumbered loopback 0 rate-limit output access-group conform-action transmit excess-action drop ! interface serial 2/2 ip unnumbered loopback 0 rate-limit input conform-action transmit excess-action drop ! access-list 100 permit tcp host any eq http CAR Based CAR Definitions ACL definition Policer can be used to control ingress traffic flow! IOS 12.0(5)T

40 40 Shaping/Policing Configuration Sample class-map match-all policed match protocol http class-map match-all shaped match access-group name ftp-downloads ! policy-map bad-boy class policed police conform-action transmit exceed-action drop class shaped shape average ! interface serial 2/1 ip unnumbered loopback 0 service-policy output bad-boy ! ip access-list extended ftp-downloads permit tcp any eq ftp-data any MQI Based ACL definition Class definitions IOS 12.1(5)T QoS policy definition QoS Policy attached to interface

41 41 CAR Policing Problem Why cannot my traffic reach CIR value? Cause: Improper setting of Bc and Be values CAR is aggressive, as drops excessive packets and the lost data needs to be retransmitted by upper layers (mainly TCP) after timeout. This also causes TCP to shrink its window reducing flow throughput. Cisco Systems recommends the following settings: Bc = 1.5 x CIR/8 Be = 2 x Bc

42 42 Congestion Management

43 43 Queuing Traffic burst may temporarily exceed interface capacity Without queuing this excess traffic will be lost Queuing allows bursty traffic to be transmitted without drops Queuing strategy defines order in which packets are transmitted through egress interface Queuing introduced additional delay which signals to adaptive flows (like TCP) to back off their throughput

44 44 Queuing Algorithms FIFO Priority (Absolute) Weighted Round Robin (WRR) Fair

45 45 FIFO Simplest queuing method with the least CPU overhead No congestion control Transmits packets in the order of arrival High volume traffic can suppress interactive flows Default queuing for interfaces > 2Mbps (i.e. Ethernet)

46 46 FIFO FIFO average queue depth dependence on load

47 47 Absolute Priority Queuing Generic Priority Queuing Custom Queuing RTP Priority Queuing Low Latency Queuing (LLQ)

48 48 Simplest QoS Algorithm: Priority Queuing Stated requirement: send it next –“If has traffic waiting, send it next” Commonly implemented –Defined behavior of IP precedence

49 49 Priority Queuing Implementation Approach Identify interesting traffic –Access lists Place traffic in various queues Dequeue in order of queue precedence

50 50 Priority Queuing (PQ) Traffic Destined for Interface Classification by: Protocol (IP, IPX, AppleTalk, SNA, DecNet, Bridge, etc.) Incoming Interface (EO, SO, S1, etc.) Interface Buffer Resources Transmit Queue Output Line Interface Hardware Ethernet Frame Relay ATM Serial Link Etc. High Medium Normal Low Q Length Defined by Q Limit Classify Absolute Priority Scheduling

51 51 Priority Queuing Scheme High Empty? Send packet from High Medium Empty?Normal Empty? Send Packet from Medium Send Packet from Normal Send Packet from Low Low Empty? YYYY NNNN

52 52 Generic PQ Drawbacks Needs thorough admission control No upper limit for each priority level High risk of low priority queues` starvation effect

53 53 Generic PQ Configuration Sample priority-list 1 protocol ip high tcp telnet priority-list 1 protocol ip high list 100 priority-list 1 protocol ip medium lt 1000 priority-list 1 interface ethernet 0/0 medium priority-list 1 default low ! interface serial 2/1 ip unnumbered loopback 0 priority-group 1 ! access-list 100 permit tcp host any eq http PQ Definition ACL definition PQ Attached to Interface

54 54 Custom Queuing (CQ) ( Weighted Round Robin ) Traffic Destined for Interface Interface Buffer Resources Q Length Deferred by Queue Limit Up to 16 3/10 1/10 Weighted Round Robin Scheduling (byte count) Classification by: Protocol (IP, IPX, AppleTalk, SNA, DecNet, Bridge, etc.) Incoming interface (EO, SO, S1, etc.) Allocate Proportion of Link Bandwidth) Classify Interface Hardware Ethernet Frame Relay ATM Serial Link Etc. 2/10 3/10 2/10 Link Utilization Ratio Transmit Queue Output Line

55 55 WRR Drawbacks Unpredictable jitter Fairness significantly depends on MTU and TCP window size Complex calculations to achieve desired traffic proportions

56 56 CQ Byte-count Calculus Distribute bandwidth to 3 queues with proportion x:y:z and packet sizes q x, q y, q z. 1.Calculate a x =x/q x, a y =y/q y, a z =z/q z. 2.Normalize and round a x, a y, a z. a x ’= round(a x /min(a x, a y, a z )); a y ’= round(a y /min(a x, a y, a z )); a z ’= round(a z /min(a x, a y, a z )). 3.Convert obtained packet proportion into byte count bc x = a x ’·q x ; bc y = a y ’·q y ; bc z = a z ’·q z. 4.Actual bandwidth share of i-th queue can be calculated with the following formula: 5.For better approximation obtained byte-counts can be multiplied by some positive whole number. Starting with IOS 12.1 CQ employs Deficit Round Robin algorithm and there is no need in such byte-count tuning.

57 57 CQ Configuration Sample queue-list 1 protocol ip 1 tcp telnet queue-list 1 protocol ip 2 list 100 queue-list 1 protocol ip 3 udp 53 queue-list 1 interface ethernet 0/0 4 queue-list 1 queue 1 byte-count 3000 queue-list 1 queue 2 byte-count 4500 queue-list 1 queue 3 byte-count 3000 queue-list 1 queue 4 byte-count 1500 queue-list 1 default 4 ! interface serial 2/1 ip unnumbered loopback 0 custom-queue-list 1 ! access-list 100 permit tcp host any eq http CQ List Definition ACL Definition CQ Attached to Interface

58 58 “Bitwise Round Robin” Fair Queuing Keshav, Demers, Shenker, and Zhang Simulates a TDM One flow per channel Time Division Multiplexer TDM Model

59 59 TDM Message Arrival Sequence Time Division Multiplexer

60 60 TDM Message Delivery Sequence Time Division Multiplexer

61 61 Fair Queuing Algorithm Employs virtual bit-by-bit round robin model (BRR) BRR dynamics are described by the equation: i-th packet from flow  arriving at time t 0 is services at time t : Servicing of i-th packet from flow  will start at S i  and finish at F i  : Additional  parameter is added for priority assignment to inactive flows : Packets are ordered for transmission according to B i  values.

62 62 Fair Queuing Approach Enqueue traffic in the sequence the TDM would deliver it As a result, be as fair as the TDM

63 63 Effects of Fair Queuing Low-bandwidth flows get –As much bandwidth as they can use –Timely service High-bandwidth flows –Interleave traffic –Cooperatively share bandwidth –Absorb latency

64 64 What Weighting Does In TDM –Channel speed determines message “duration” In WFQ –Multiplier on message length changes simulated message “duration” Result: –Flow’s “fair” share predictably unfair

65 65 Weighted Fair Queuing (WFQ) Traffic Destined for Interface Interface Buffer Resources Configurable Number of Queues Flow-Based Classification by: Source and destination address Protocol Session identifier (port/socket) Weight Determined by: Requested QoS (IP Procedure, RSVP) Frame Relay FECN, BECN, DE (For FR Traffic) Flow throughput (weighted-fair) Weighted Fair Scheduling Classify Transmit Queue Output Line

66 66 Weighted Fair Queuing (WFQ) Fair bandwidth per flow allocation Low delay for interactive applications Protection from ill-behaved sources

67 67 Weighted Fair Queuing (WFQ) Flow classified by the following fields: Source address Source port Destination address Destination port ToS Weight of each flow (queue) depends on ToS: weight = 1/(precedence+1) Bandwidth distributed in 1/weight proportions

68 68 Weighted Fair Queuing (WFQ) Packets are ordered according to the expected virtual departure time of their last bit. Low volume flows have preference over high volume transfers. Low volume flow is identified as using less than its share of bandwidth. The special queue length threshold value is established, after which only low volume flows can enqueue. All the packets, that belong to high volume flows are dropped.

69 69 Drawbacks of Weighted Fair Queuing Requires more sorting than other approaches

70 70 Weighted Fair Queuing (WFQ) FTP Telnet t Delay

71 71 Weighted Fair Queuing (WFQ) FTP Telnet t Delay

72 72 WFQ Configuration Sample interface serial 2/1 ip unnumbered loopback 0 fair-queue Queue Threshold (packets) Maximal number of queues Number of reservable queues

73 73 RTP Priority Queuing Classifies only by UDP port range Only even ports from the range are classified Establishes upper limit via integrated policer Excess traffic dropped during congestion periods RTP PQ has priority over LLQ

74 74 RTP PQ Configuration Sample interface serial 2/1 ip unnumbered loopback 0 ip rtp priority Starting UDP port Range length Bandwidth Limit (kbps)

75 75 Low Latency Queuing (LLQ) Implemented using MQI Very rich classification criteria (class-map) Establishes upper limit via integrated policer Excess traffic dropped during congestion periods

76 76 LLQ Configuration Sample class-map match-all voice match access-group name voip ! policy-map llq class voip priority 30 class class-default fair-queue 64 ! interface serial 2/1 ip unnumbered loopback 0 service-policy output llq ! ip access-list extended voip permit ip host any ACL definition Class definitions IOS 12.0(5)T LLQ policy definition LLQ Policy attached to interface

77 77 Class Based WFQ (CBWFQ) Based on the same algorithm as WFQ Weights can be manually configured Allows to easily specify guaranteed bandwidth for a class Configuration based on Cisco MQI

78 78 CBWFQ Configuration Sample class-map match-all premium match access-group name premium-cust class-map match-all low-priority match protocol napster ! policy-map cbwfq-sample class premium bandwidth 512 class low-priority shape average 128 shape peak 512 class class-default fair-queue 64 ! interface serial 2/1 ip unnumbered loopback 0 max-reserved-bandwidth 85 service-policy output cbwfq-sample ! ip access-list extended premium-cust permit ip host any ACL definition Class definitions IOS 12.0(5)T Qos policy definition QoS Policy attached to interface

79 79 CBWFQ Configuration Sample class-map match-all premium match access-group name premium-cust class-map match-all voice match ip precedence flash ! policy-map total-shaper class class-default shape average 1536 service-policy class-policy policy-map class-policy class premium bandwidth 512 class voice priority 64 class class-default fair-queue 128 IOS 12.1(5)T Hierarchical Design interface fastethernet 1/0 ip unnumbered loopback 0 max-reserved-bandwidth 85 service-policy output total-shaper ! ip access-list extended premium-cust permit ip host any

80 80 Hierarchical CBWFQ Limitations Only two levels of hierarchy are supported set command not supported in child policy Shaping allows only in parent policy LLQ can be configured only either in child or parent policies but not in both FQ allowed only in child policy

81 81 Congestion Avoidance

82 82 Global Synchronization Effect Load t Link Capacity Avg. Throughput

83 83 Tail Drop and TCP Flow Control Packet drops from all TCP sessions simultaneously High probability of multiple drops from the same TCP session Uniformly distributed drops from high volume and interactive flows Result: Low average throughput!

84 84 Random Early Detection (RED) Starts randomly dropping packets before actual congestion occurs Keeps average queue depth low Increases average throughput Developed by Van Jacobson in 1993

85 85 Global Synchronization Removed Load t Link Capacity Avg. Throughput

86 86 Random Early Detection (RED) p 1 0 q avg q max Tail Drop p 1 0 q avg  max  min  RED Adjustable

87 87 Random Early Detection (RED)  min – Minimal threshold after which RED starts packet drops. Minimal recommended value is 5 packets.  max – Maximal threshold after which all packets are dropped. Recommended value is 2-3 times  min.  - Mark probability denominator denotes packet drop probability at  max average queue depth. Optimal value – 0.1.  - Exponential weighting factor determines the level of backward value-dependence in average queue depth calculation: q avg = (q old · (  )) + (q cur · 2 -  ) General recommendation  = 9. RED Parameters:

88 TCP Rate Control - 1 In TCP, the spacing of ACKs and the window size in the ACKs controls the transmitter’s rate. Rate Control manipulates the ACKs as they pass through the rate control device by: –Adjusting the size of TCP ACK window –Inserting new ACKs –Re-spacing existing ACKs Rate Control works only with TCP; other methods, such as Token Bucket, must be used with UDP. Rate Control violates the protocol layering design, as it allows network devices to manipulate a higher-layer protocol’s operation. Nevertheless, it usually functions well and provides fine-grained control.

89 TCP Rate Control - 2 Example:

90 90 Weighted Random Early Detection (WRED) Modified version of RED Weights determine the set of parameters:  min,  max and . Weight depends on ToS field value Interactive flows are preserved

91 91 WRED Configuration Sample interface serial 2/1 ip unnumbered loopback 0 random-detect random-detect random-detect random-detect random-detect …  min  Interface based  max

92 92 WRED Configuration Sample policy-map red class class-default random-detect random-detect random-detect random-detect random-detect … interface Serial2/1 ip unnumbered loopback 0 service-policy output red  min  MQI based  max WRED is incompatible with LLQ feature!

93 93 Link Optimization

94 94 Link Fragmentation and Interleaving (LFI) Voice Packet Jumbogram 64 kbps 1500 bytes  190ms For links < 128kbps

95 95 Link Fragmentation and Interleaving (LFI) 64 kbps Supported interfaces: Multilink PPP Frame Relay DLCI ATM VC

96 96 LFI Configuration Sample interface virtual-template 1 ip unnumbered loopback 0 ppp multilink ppp multilink interleave ppp multilink fragment-delay 30 ip rtp interleave … MLP version

97 97 Signaling

98 98 Resource Reservation Protocol (RSVP) End-to-end QoS signaling protocol Used to establish dynamic reservations over the network Always establishes simplex reservation Supports unicast and multicast traffic Actually uses WFQ and WRED mechanisms

99 99 Resource Reservation Protocol (RSVP)

100 100

101 101 Reservation Types: Guaranteed Rate (uses WFQ and LLQ) Controlled Load (uses WRED) DistinctShared ExplicitFixed Filter (FF)Shared Explicit (SE) Wildcard X Wildcard Filter (WF)

102 102 Resource Reservation Protocol (RSVP)

103 103 QoS Policy Propagation over BGP QoS policy can be shared inside single AS or among different ASs. Community attribute is usually used for color assignments Prevents manual policy changes in network devices

104 104 QoS Policy Propagation over BGP

105 105 QPPB Configuration Sample ip bgp-community new-format ! router bgp 10 neighbor remote-as 20 neighbor send-community neighbor route-map cout out ! route-map cout permit 10 match ip address 20 set community 60:9 ! access-list 20 permit Router A ip bgp-community new-format ! router bgp 20 neighbor remote-as 10 table-map mark-pol ! route-map mark-pol permit 10 match community 1 set ip precedence flash ! ip community-list 1 permit 60:9 ! interface Serial 0/1 ip unnumbered loopback 0 bgp-policy source ip-prec-map Router B

106 106 Topics not Covered Multiprotocol Label Switching (MPLS) Frame Relay QoS ATM QoS Distributed Queuing Algorithms Multicast

107 107 Conclusion QoS is not an exotic feature any more QoS allows specific applications (VoIP, VC) to share network infrastructure with best-effort traffic QoS in IP networks simplifies their functionality avoiding Frame Relay and ATM usage

108 108 ? Questions???


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