đề tài qos over mpls for hutech network

Table of ContentsArchitecture of Subject...4 Relation Words ...5 Multiprotocol label switching ...6 Actuality of MPLS at VietNam...6 Advantage of MPLS ...8 Disadvantage of MPLS...8 Icon

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Đề tài : QoS over MPLS for Hutech network

Table of Contents

Architecture of Subject 4

Relation Words 5

Multiprotocol label switching 6

Actuality of MPLS at VietNam 6

Advantage of MPLS 8

Disadvantage of MPLS 8

Icon use in subject 9

CHAPTER 1: INTRODUCTION ABOUT NETWORK SYSTEM OF HUTECH UNIVERSITY 10

1.1 Description about network system of Hutech University .11

1.2 Important problem and solution .11

1.3 Task of subject 12

CHAPTER 2: QOS OVER MPLS NETWORK 13

Part 1: Overview about MPLS 14

2.1 Architecture of MPLS packet 15

2.1.1 Label .15

2.1.2 Experimental .15

2.1.3 Bottom of Stack .15

2.1.4 Time to Live 16

2.2 Operating of MPLS network .16

2.2.1 MPLS domain .16

2.2.2 Ingress and egress node .17

2.2.3 Label Switch Router .17

2.2.4 Label Switch Path .18

2.2.5 Forwarding Equivalent Class 18

2.2.6 Label Distribution Protocol .19

2.3 Command for configure MPLS 20

Part 2: Overview about QoS 22

2.4 Architecture of QoS 23

2.4.1 IntServ model 23

2.4.2 DiffServ model 25

2.4.3 Different between IntServ model and DiffServ model 27

2.5 Classification .27

2.6 Marking .27

2.7 Queuing tools 28

2.7.1 First In-First Out Queuing .29

2.7.2 Priority Queuing 31

2.7.3 Custom Queuing .32

2.7.4 Weighted Fair Queuing 33

2.7.5 Class-Based Weighted Fair Queuing .38

2.7.6 Low-latency Queuing .41

Part 3: QoS over MPLS 44

2.8 Relation about IPP, DSCP and MPLS EXP .45

2.8.1 IPP 45

2.8.2 DSCP 46

2.8.3 MPLS EXP 47

2.9 DiffServ with IP packets .48

2.10 DiffServ with MPLS packets .50

2.11 DiffServ Tunneling Modes for MPLS networks 52

2.11.1 Pipe Model .52

2.11.2 Short-Pipe Model .54

2.11.3 Uniform Model .55

2.12 Steps implement QoS over MPLS 57

CHAPTER 3: NETWORK DESIGN AND IMPLEMENT 58

3.1 Building solution for Hutech network 60

3.1.1 Real model of Hutech network .60

3.1.2 Solution model for Hutech network 61

3.2 Building simulation model to resolve for Hutech network .62

3.2.1 Simulation model .62

3.2.2 Implement QoS over MPLS in simulation model .64

3.3 Get Result .72

Get Result and Define of develop in Subject 74

References 75

Index 76

Architecture of subject

Subject includes three chapters:

Chapter 1: Introduction about network system of Hutech University, problem of

Hutech network system, solution to resolve

Chapter 2: Chapter 2 includes three parts.

Part 1: Overview about MPLS, architecture MPLS packet, operation of MPLSnetwork, command line for configure MPLS operation

Part 2: Overview about QoS, architecture of QoS, classification, marking andqueuing tool

Part 3: QoS over MPLS, relative about IPP, DSCP and MPLS EXP, DiffServ with

IP packet and MPLS packet, DiffServ tunneling mode, steps implement QoS overMPLS network

Chapter 3: Network design and implement Deploy QoS over MPLS, get result

and define of develop in subject

Relation Words

IPP : IP Precedence (value support implement QoS)

DSCP : Differentiated Services Code Point

MPLS : Multiprotocol Label Switching

EXP : Experimental

QoS : Quality of Service

LSP : Label Switched Path

LSR : Label Switched Router

IntServ :Iintegrated services

DiffServ : Differentiated Services

LLQ : Low-latency Queuing

FIFO : First In – First Out

CQ : Custom Queuing

WFQ : Weighted Fair Queuing

CBWFQ : Class-Based Weighted Fair Queuing

LDP : Label Distribution Protocol

Multiprotocol Label Switching

Multiprotocol Label Switching (MPLS) is a standards-approved technology forspeeding up network traffic flow and making it easier to manage MPLS involvessetting up a specific path for a given sequence of packets, identified by a label put

in each packet, thus saving the time needed for a router to look up the address tothe next node to forward the packet to MPLS is called multiprotocol because itworks with the Internet Protocol (IP), Asynchronous Transport Mode (ATM), andframe relay network protocols With reference to the standard model for a network(the Open Systems Interconnection, or OSI model), MPLS allows most packets to

be forwarded at the layer 2 (switching) level rather than at the layer 3 (routing)level In addition to moving traffic faster overall, MPLS makes it easy to manage anetwork for quality of service (QoS) For these reasons, the technique is expected

to be readily adopted as networks begin to carry more and different mixtures oftraffic

Actuality of MPLS at VietNam

-With VietNam, MPLS deployment are building in communication network atVNPT head of company VietNam With VoIP project is deploying, VNPTestablished an axle MPLS network with three LSR core LSRs edge will beinvested and extended at places have large demand as Hai Phong, Quang Ninh atnorth, Da Nang, Khanh Hoa…at medium, Binh Duong, Dong Nai, Ba Ria – VungTau…at south Next, FPT Telecom, Viettel, electricity are taked part and createcompetition environment with high QoS and cheap

- Present, not including companies and foreign office representative, there are alot of home companies in finance field, insurance, bank use this service (Bao Vietinsurance company, Dong A bank…) Beside that, arrange state as Ministry ofFinance, customs, treasury, tax associated together by VPN/MPLS

-VPN/MPLS technology officially deployed, applied and test successfully andinserted to exploited from 2003 by VDC 2004, VPN MPLS solution of VDC

saved up technology information IT Week 14 gold cup and extended to exploited

on all 64 provinces of all the country with trade name VPN/VNN

- VPN/VNN MPLS solution of VDC apply and deploy to rely on pass anddevice technology of Cisco, with target create a network solution safe, security,slow late and intergrate with each apply as Data, Voice, Video…

Price for first setup: include price for setup and link to MPLS/VNN

TDNH(VND/channel/time)

Price for setup, link

to networkVPN/VNN(VND/channel/time)

Price for month: (Upcountry price + Service price MPLS/VNN)

TDNH(VND/port /month)

Price for all (VND/port /month)

-Security (absolute security in core MPLS network and local loop network).

-Flexible (Easy for wire-open)

-Easy for administrator control

Disadvantage of MPLS:

-VietNam has limit human resource for control MPLS network system.

-Device support MPLS network is limit

Icon use in subject

CHAPTER 1: INTRODUCTION ABOUT NETWORK

SYSTEM OF HUTECH UNIVERSITY

1.1 Description about network system of Hutech University.

Hutech University include three branches, branch 1 at Binh Thanh distinct, branch

2 at Phu Nhuan distinct, and the last branch at Thu Duc distinct Three branchesjoin together by Frame-Relay technology In every branch, include type of faculty:-Faculty of information technology

Figure 1.1- Network diagram of Hutech University

1.2 Important problem and solution.

Hutech University is carrying to enlarge infrastructure Up to this time, the number

Hutech University is old and stunted This network system can’t satisfy need tocommunication information between branches Network system has limitbandwidth and old technology, so obstruct at any time in network system.

To make good that problem, solution for Hutech University network system must

a new technology, high effect, low cost We have too much solutions, and the bestsolution is QoS over MPLS

1.3 Task of Subject.

With Hutech’s problem, we will build technology QoS over MPLS for Hutechnetwork We design and implement to preference for important traffic, examplevideo traffic, voice traffic… To limit obstruct

Model solution for Hutech network:

Figure 1.2 – Solution model for Hutech network

CHAPTER 2: QOS OVER MPLS NETWORK

PART 1: OVERVIEW ABOUT MPLS

2.1 Architecture of MPLS packet.

MPLS label is a field with 32 bit with hard architecture

Figure 2.1 - MPLS label architecture

2.1.1 Label.

Label include 20 bit in header MPLS, their value between 0 to 220–1 and it has

1,048,575 labels However, 16 value labels first aren’t use In IP network,transport packets must use IP source and IP destination, but with MPLS network,packets are transport by label Routers use label instead for IP address

2.1.2 Experimental.

From bit 20 to bit 22 is exp field, three bits used for quality of services Exp bitsimilar Precedence bit in IP header In IP network, implement quality of service isuse IP Precedence or DSCP, but with MPLS network is use Experimental

2.1.3 Bottom of Stack.

Bit 23 BoS (Bottom of Stack) in MPLS header, if label is bottom of stack, it has

value 1, if label isn’t bottom of stack it has value 0

Figure 2.2 – Label of Stack

In MPLS network, when transport packets, every router in MPLS network is uselabel for forward packets to exactly destination, router is use label table.

2.1.4 Time to Live.

From bit 24 to bit 31 are used for TTL (Time to Live) field This field similar TTL

field in IP header If router can’t finds the destination of packet but router is

forwarding that packet, this action will loop So TTL field make avoid look When

packet through every router it’s drop 1 When TTL field has value 0, router will

drop it

2.2 Operating of MPLS network.

2.2.1 MPLS domain.

MPLS domain include two parts:

-Core network (core)

-Edge network (edge)

With cord network, core network operate complete in MPLS network, routeroperate in core network will assign label to packet and forward that packet to nextrouter With edge network, router in edge network must do two tasks; two tasksare imposition label and disposition label from packet In case imposition withpacket through from IP network to MPLS network, packet is imposition label andthat operation is call imposition With case packet through from MPLS network to

IP network, packet is disposition label and operation is call disposition

Figure 2.3 - Imposition and Disposition

2.2.2 Ingress and Egress node.

When packet goes from IP network to MPLS network, packet will assign label.And operation is call ingress

When packet goes from MPLS network to IP network, packet will unassignedlabel And operation is call egress

Both ingress and egress node are edge router

2.2.3 Label Switch Router.

A label switch router (LSR) is a router that supports MPLS It is capable ofunderstanding MPLS labels and of receiving and transmitting a labeled packet on adata link Three kinds of LSRs exist in an MPLS network:

Ingress LSRs receive a packet that is not labeled yet, insert a label (stack) infront of the packet, and send it on a data link

Egress LSRs receive labeled packets, remove the label(s), and send them on adata link Ingress and egress LSRs are edge LSRs

Intermediate LSRs receive an incoming labeled packet, perform an operation

on it, switch the packet, and send the packet on the correct data link

An LSR can do the three operations: pop, push, or swap

It must be able to pop one or more labels (remove one or more labels from the top

of the label stack) before switching the packet out An LSR must also be able topush one or more labels onto the received packet If the received packet is alreadylabeled, the LSR pushes one or more labels onto the label stack and switches outthe packet If the packet is not labeled yet, the LSR creates a label stack and pushes

it onto the packet An LSR must also be able to swap a label This simply means thatwhen a labeled packet is received, the top label of the label stack is swapped with anew label and the packet is switched on the outgoing data link

An LSR that pushes labels onto a packet that was not labeled yet is called animposing LSR because it is the first LSR to impose labels onto the packet One

the labeled packet before switching out the packet is a disposing LSR One that

does disposition is an egress LSR

2.2.4 Label Switch Path.

A label switched path (LSP) is a sequence of LSRs that switch a labeled packetthrough an MPLS network or part of an MPLS network Basically, the LSP is thepath through the MPLS network or a part of it that packets take The first LSR of anLSP is the ingress LSR for that LSP, whereas the last LSR of the LSP is the egressLSR All the LSRs in between the ingress and egress LSRs are the intermediateLSRs

Figure 2.4- Label Switch Path

2.2.5 Forwarding Equivalent Class.

A Forwarding Equivalence Class (FEC) is a group or flow of packets that areforwarded along the same path and are treated the same with regard to theforwarding treatment All packets belonging to the same FEC have the same label.However, not all packets that have the same label belong to the same FEC, becausetheir EXP values might differ; the forwarding treatment could be different, and theycould belong to a different FEC The router that decides which packets belong towhich FEC is the ingress LSR This is logical because the ingress LSR classifiesand labels the packets Following are some examples of FECs:

-Packets with Layer 3 destination IP addresses matching a certain prefix

-Multicast packets belonging to a certain group

-Packets with the same forwarding treatment, based on the precedence or IPDiffServ Code Point (DSCP) field.

-Layer 2 frames carried across an MPLS network received on one VC or(sub)interface on the ingress LSR and transmitted on one VC or (sub)interface onthe egress LSR

-Packets with Layer 3 destination IP addresses that belong to a set of BorderGateway Protocol (BGP) prefixes, all with the same BGP next hop

This last example of a FEC is a particularly interesting one All packets on theingress LSR for which the destination IP address points to a set of BGP routes inthe routing table—all with the same BGP next-hop address—belong to one FEC

It means that all packets that enter the MPLS network get a label depending onwhat the BGP next hop is

2.2.6 Label Distribution Protocol.

To get packets across a label switched path (LSP) through the MPLS network, allLSRs must run a label distribution protocol and exchange label bindings When allthe LSRs have the labels for a particular Forwarding Equivalence Class (FEC), thepackets can be forwarded on the LSP by means of label switching the packets ateach LSR The label operation (swap, push, pop) is known to each LSR by lookinginto the LFIB The LFIB (which is the table that forwards labeled packets) is fed

by the label bindings found in the LIB The LIB is fed by the label bindingsreceived by LDP, Resource Reservation Protocol (RSVP), MP-BGP, or staticallyassigned label bindings Because RSVP distributes the labels only for MPLStraffic engineering and MP-BGP distributes the labels only for BGP routes, youare left with LDP for distributing all the labels for interior routes Therefore, alldirectly connected LSRs must establish an LDP peer relationship or LDP sessionbetween them The LDP peers exchange the label mapping messages across thisLDP session A label mapping or binding is a label that is bound to a FEC The

FEC is the set of packets that are mapped to a certain LSP and are forwarded overthat LSP through the MPLS network LDP has four major functions:

-The discovery of LSRs that are running LDP

-Session establishment and maintenance

-Advertising of label mappings

-Housekeeping by means of notification

When two LSRs are running LDP and they share one or more links between them,they should discover each other by means of Hello messages The second step isfor them to establish a session across a TCP connection Across this TCPconnection, LDP advertises the label mapping messages between the two LDPpeers These label mapping messages are used to advertise, change, or retract labelbindings LDP provides the means to notify the LDP neighbor of some advisoryand error messages by sending notification messages

2.3 Command for configure MPLS.

Command used for configure MPLS operate

Command used for verify MPLS operate

PART 2: OVERVIEW ABOUT QOS.

2.4 Architectures of QoS.

There are three part for enforce QoS :

-QoS in a environment single network (as arrange sequence, make listssequencing and tools for transmit information on network)

-The technique transmit signal for regulate QoS among factors into network.-The policy QoS, administer, and calculate features for control and managetransmit information among nodes into network

2.4.1 IntServ model.

Integrated services (IntServ) defines a different model for QoS than does DiffServ.IntServ defines a signaling process by which an individual flow can request thatthe network reserve the bandwidth and delay needed for the flow The originalwork grew out of the experiences of the IETF in multicasting the audio and videofor IETF meetings in the early to mid-1990s

Figure 2.5- IntServ model

IntServ admission control decides when a reservation request should be rejected Ifall requests were accepted, eventually too much traffic would perhaps beintroduced into the network, and none of the flows would get the requestedservice IntServ uses Resource Reservation Protocol for signaling to reserve thebandwidth With a full IntServ implementation (more on that later), the originator

of the flow (Hannah) begins signaling At each router along the route, the routerasks itself, “Can I support this request?” If the answer is yes, it forwards therequest to the next router Each router holds the bandwidth temporarily, waiting onthe confirmation to flow back to the originator (Hannah) When each router seesthe reserve RSVP command flow back to the originator, each router completes thereservation What does it mean for the router to “reserve” something? In effect, therouter reserves the correct queuing preferences for the flow, such that theappropriate amount of bandwidth is allocated to the flow by the queuing tool.RSVP can also request a certain (low) amount of delay, but implementing aguarantee for delay is a little more difficult; IOS, for instance, just reserves thequeuing preference In fact, IntServ RFCs actually define the term “guarantee” as

a relatively loose goal, and it is up to the actual implementation to decide howrigorous or general to make the guarantees RSVP continues signaling for theentire duration of the flow If the network changes, or links fail and routingconvergence occurs, the network may no longer be able to support the reservation.Therefore, RSVP reserves the bandwidth when the flow initializes and continues

to ensure that the flow can receive the necessary amount of bandwidth IntServ hassome obvious disadvantages, and it has several advantages IntServ actuallypredates DiffServ; DiffServ, to some degree, was developed to provide anInternet-scale QoS model, because IntServ scales poorly IntServ expects the hosts

to signal for service guarantees, which brings up two issues—whether the hostscan be trusted by the network and whether the hosts actually support RSVP.Alternatively, routers can be configured to reserve bandwidth on behalf of hosts,but the configuration can quickly become an administrative problem because

additional configuration would need to be added for each reserved flow AlsoIntServ works best when all intermediate networks support IntServ.

2.4.2 DiffServ model.

The DiffServ model designed to repair limits of IntServ model The DiffServmodel can flexible high and extend large Instead of perform through QoS andunity on all line as IntServ model, the Diffserv model perform QoS individually oneach router, so DiffServ unnecessary signal to follow each flow thereforeeconomize bandwidth and can extend, approprivate with large network model.Salient features in manage resources of DiffServ model implemented at:

-The DiffServ model don’t implement to signal, shake hand when establishflow therefore it is losed bandwidth for signal

-The DiffServ model manage resource effectly because it don’t reserveresources for any of a services Services devided follow sequence priority, whichservice has priority higher will provided resource at regime better, when haven’tflow, the resource will be returned for system and used by other services

Activity of DiffServ

Activity of DiffServ can describle as follows:

First, information packages classified become a lot of priority group from low tohigh according to feature of each service, device will provide authority usedresource more priority, resource will used by lower group if higher group don’tuse

Video packet Voice packet Data packet

Figure 2.6 - DiffServ Model

Solution QoS follow DiffServ performed follow steps:

Mark and classify package First, packages will marked for differentiate, after thatarranged in group conformably Mark and arrange will helf for perform QoS atafter steps:

-Manage obstructed: Structure manage obstruct to performed on interfaces ofnetwork device When package come to these interfaces, package will classifiedfollow each queue rely on priority

-Avoid obstructed: Structure reject package before obstructe

-Put threshold: Structure put upper threshold, under threshold for bandwidth,specific is bandwidth will ensured a under threshold minimum and when largerthan upper threshold package can be rejected or move to queue

-Press header: Header hold large part in a package but don’t have realinformation, structure press header will economize bandwidth -

Fragmentate: data packages often have large length, This event will cause late and

obstructed Structure fragmentate will mince these packages become smallerpackages for avoid obstructed.

2.4.3.Difference between InServ model and DiffServ model.

Use signal protocol RSVP for fight

resource

Don’t use protocol

Use for small network and little flow

network

Use for large network and smallnetwork, have a lot of flownetwork

Resource wasted high Resource wasted little

Don’t manage resource because

marked before that

Manage resource to rely onpriority of each flow

Tabel 2.1- Compare IntServ model and DiffServ model

2.5 Classification.

Almost every QoS tool uses classification to some degree To put one packet into

a different queue than another packet, the IOS must somehow differentiatebetween the two packets To perform header compression on Real Time Protocol(RTP) packets, but not on other packets, the IOS must determine which packetshave RTP headers To shape data traffic going into a Frame Relay network, so thatthe voice traffic gets enough bandwidth, the IOS must differentiate between Voiceover IP (VoIP) and data packets If an IOS QoS feature needs to treat two packetsdifferently, you must use classification Because most QoS tools need todifferentiate between packets, most QoS tools have classification features In fact,many of you will already know something about several of the QoS tools

described in this book, and you will realize that you already know how to performclassification using some of those tools For instance, many QoS tools enable you

to classify using access control lists (ACLs) If ACL 101 permits a packet, aqueuing tool might put the packet into one queue; if ACL 102 permits a packet, it

is placed in a second queue; and so on In one way of thinking, queuing couldinstead be called classification and queuing, because the queuing feature mustsomehow decide which packets end up in each queue Similarly, traffic shapingcould be called classification and traffic shaping, policing could be calledclassification and policing, and so on Because most QoS tools classify traffic,however, the names of most QoS tools never evolved to mention the classificationfunction of the tool Most classification and marking tools, like the other types ofQoS tools, generally operate on packets that are entering or exiting an interface.The logic works something like an ACL, but the action is marking, as opposed toallowing or denying (dropping) a packet More generally, classification andmarking logic for ingress packets can be described as follows:

-For packets entering an interface, if they match criteria 1, mark a field with avalue

-If the packet was not matched, compare it to criteria 2, and then mark apotentially different field with a potentially different value

-Keep looking for a match of the packet, until it is matched, or until theclassification logic is complete

2.6 Marking.

Marking accept network devices classify package or frame rely on gait specificdescription flow Some gait description flow are used for mark as: class of service(CoS), DSCP, IP priority, MPLS EXP bit, group QoS Marking is used to establishinformation in heading package class two or class three

Mark package or frame and classify accept network device discriminate easilypackages or frame marked Marking is element useful because it accept networkdevice recognize easily packages or frames follow specific classes Then QoStechnical can apply compatible for right ensure with manage QoS policies.

Marking include organize some bits inner a data-link class or network header withpurpose helpful for QoS tools of other device can classify rely on some valuemarked We can mark a lot of field correlative for each specific request Somefield are used a lot of, other field are not Some choose inner mark to grill with alldevice inner local network while other ones only use on base hardware default.And making on WAN same

2.7 Queuing tools.

We have one way for control information overflow, the way is use algorithmqueue for arrange traffic and determine some methods for decentralization priority

of traffic IOS of Cisco support some tool following:

- First-in, first-out (FIFO)

- Priority queuing (PQ)

- Custom queuing (CQ)

- Weighted fair queuing (WFQ)

- Low Latency Queuing (LLQ)

Every algorithm was design for solve problem when transmit messages innetwork, and it is effect for network

2.7.1 First In – First Out Queuing.

The first reason that a router or switch needs output queues is to hold a packet

Whereas the other queuing tools in this chapter also perform other functions, likereordering packets, FIFO Queuing just provides a means to hold packets whilethey are waiting to exit an interface FIFO Queuing does not need the two mostinteresting features of the other queuing tools, namely classification andscheduling FIFO Queuing uses a single queue for the interface Because there isonly one queue, there is no need for classification to decide the queue into whichthe packet should be placed Also there is no need for scheduling logic to pickwhich queue from which to take the next packet The only really interesting part ofFIFO Queuing is the queue length, which is configurable, and how the queuelength affects delay and loss FIFO Queuing uses tail drop to decide when to drop

or enqueue packets If you configure a longer FIFO queue, more packets can be inthe queue, which means that the queue will be less likely to fill If the queue is lesslikely to fill, fewer packets will be dropped However, with a longer queue,packets may experience more delay and jitter With a shorter queue, less delayoccurs, but the single FIFO queue fills more quickly, which in turn causes moretail drops of new packets These facts are true for any queuing method, includingFIFO

Figure 2.7 – FIFO Queue

Queue has three packets 4, 3, 2, 1, if follow queue packet 1 can pass first and nextare three packets 2, 3, 4

2.7.2 Priority Queuing.

Priority Queuing’s most distinctive feature is its scheduler PQ schedules trafficsuch that the higher-priority queues always get serviced, with the side effect ofstarving the lower-priority queues With a maximum of four queues, called High,Medium, Normal, and Low, the complete logic of the scheduler can be easilyrepresented The PQ scheduler has some obvious benefits and drawbacks Packets

in the High queue can claim 100 percent of the link bandwidth, with minimaldelay, and minimal jitter The lower queues suffer, however In fact, whencongested, packets in the lower queues take significantly longer to be servicedthan under lighter loads In fact, when the link is congested, user applications maystop working if their packets are placed into lower-priority queues

Most of the rest of the details about PQ can be easily understood PQ classifiespackets based on the content of the packet headers It uses a maximum of fourqueues, as mentioned earlier The only drop policy is tail drop—in other words,after classifying the packet, if the appropriate queue is full, the packet is dropped.The length of each queue, which of course affects packet loss and delay, can bechanged—in fact, PQ can set the queue length to a value of zero, which means thequeue length is infinite

PQ works great for QoS policies that need to treat one type of traffic with theabsolute best service possible However, PQ’s service for the lower queuesdegrades quickly, making PQ impractical for most applications today Forinstance, even running one FTP connection, one web browser, one NetMeetingcall, and two VoIP calls when creating the output for this section of the book, theTCP connections for the FTP and HTTP traffic frequently timed out.

2.7.3 Custom Queuing.

Custom Queuing (CQ) followed PQ CQ addresses the biggest drawback of PQ byproviding a queuing tool that does service all queues, even during times ofcongestion It has 16 queues available, implying 16 classification categories,which is plenty for most applications The negative part of CQ, as compared to

PQ, is that CQ’s scheduler does not have an option to always service one queuefirst (like PQ’s High queue) so CQ does not provide great service for delay- andjitter-sensitive traffic

CQ was design for some applications or associates, and CQ can share information ofnetwork with different applications by small traffic and delay time can agree Inenvironment like that, bandwidth must be balance with every application and user If weuse particularity of CQ algorithm support by Cisco for make sure about bandwidth, where

in the network has obstructed network, or make sure for transmit information will be okwith bandwidth we issue and establish Requests of guest will be arrange by set up sometools, size of queue with every class of packet and process of packet are use round-robinalgorithm

Figure 2.9 – Classification and move packet into SNA queue.

In figure 3.7.3, packing of SNA system need ensure some small amount of service

We can provide a haft of bandwidth for transmit data in SNA system, and we issueremain bandwidth for another protocol, example IP or IPX Algorithm will arrangemessages into 1 of 17 queues (queue 0 store message of system of system,example test keepalive always send update connection….) Router will do that,arrange information into queue form queue 1 to queue 16, and router use round-robin algorithm, arrange every byte That function is make sure not application canoperate can use resource highest than system issue Similar PQ, CQ is configuringstatic and don’t automatic update if network has change

2.7.4 Weighted Fair Queuing.

Weighted Fair Queuing differs from PQ and CQ in several significant ways Thefirst and most obvious difference is that WFQ does not allow classification options

to be configured! WFQ classifies packets based on flows A flow consists of allpackets that have the same source and destination IP address, and the same sourceand destination port numbers So, no explicit matching is configured The other

favors low-volume, higher-precedence flows over large-volume, lower-precedenceflows Also because WFQ is flow based, and each flow uses a different queue.Flow-Based WFQ, or just WFQ, classifies traffic into flows Flows are identified by atleast five items in an IP packet:

-IP source

-IP destination

-Transport protocol

-TCP source port or UDP source port

-TCP destination port or UDP destination port

-Value Precedence of IP packet

Because WFQ classification packet to rely on row of different traffic and then itmove that row into different queue, router has total different queues These queuesmore than every different queue tools WFQ use algorithm different withalgorithm every queue tools, that different is control more traffic However, WFQcan describe like this:

-Every rows have the same priority of packet will be have the same bandwidth,and it don’t care rows have how many byte in every traffic row

-If row has different precedence, if the row has precedence highest with hasbandwidth high

-Finally, WFQ will priority for rows have traffic small and priority high

Example, if WFQ is controlling 10 queues with different IP Precedence in port has

128 kbps; every traffic row can have 12.8 kbps, so delay time will be big

And goal second of WFQ is provide enough bandwidth for traffic rows have highprecedence For do that, rows issue number IP Precedence + 1 Example, traffichas IP Precedence has value 7, and this traffic has bandwidth high bandwidth of IPPrecedence has value 0

Figure 2.10 – Model of operation WFQ

Time process WFQ

To get purpose issue bandwidth, WFQ use regulator time so simple Regulatortime use packet has one after another index low sequence number, and it call SN,when it transmit packet in the next hardware queue

Mechanism WFQ issues every packet with one after another index SN whenpacket goes into WFQ queue Process issue one after another SN is a partimportant in mechanism regulator time of WFQ Regulator time WFQ calculatesone after another numbers SN by parameters of flow traffic, include length andpriority of packet

Syntax to calculate one after another number SN of packet in flow traffic like this:

SN= SN number before +( weight*length of new packet).

Weight like this:

Weight=32384 / (IP_Precedence+1)

Syntax reference to length of new packet, weight of flow traffic and value of SNbefore.

By consider length of packet, and calculator one after another SN number may behas a high SN number for packets, and packets have big size and one after another

SN number low more than packets have small size Include one after another SNnumber of packet before it moves in queue, syntax will calculator and result is abiggest SN number than packets in queue has biggest packet It will issue (IPP+1),packets have high priority, and it will have low SN

In figure 2.11, describe how two packets issue two one after another Calculatorone after another number so easy However, the first packet in a flow traffic isdon’t has one after number SN of the first packet if it was use that syntax Syntaxdescribe one after another SN of the end packet will move into hardware queue,and it use one after number SN follow a new next flow

Figure 2.11- Describe calculator SN (Sequence Number)

After one after number SN was issue, next work chooses which the packet will beremoved in regulator time device It will take packet has low SN in queue

Policy to reject packet of WFQ, number and length of queue.

In operator of router, although traffic match in queue, but if traffic through routerstill crush, router must reject packet to avoid obstructed WFQ use second processand call modified tail drop for choose what packet will reject

-First, WFQ will consider the best limit of all packets in queue, and limit call ishold-queue limit If packet goes to queue and hold-queue is limit, packet will bedrop That decide don’t belong to one queue, it belong to queue system of WFQ.Different way, hold-queue limit is a local number, and calculates by total WFQqueue

-Second, WFQ consider length of queue and packets are move in queue.Before packets move into queue, congestive discard threshold will test with thetrue length of queue If the length of queue longer than CDT, packet will be drop,but new packet will not drop Packet with one after another number in queues ofWFQ will be drop

Figure 2.12 – Describe process of WFQ

The hold-queue size limits the total number of packets in all of the flow orconversation queues However, CDT limits the number of packets in eachindividual queue If CDT packets are already in the queue into which a packet

should be placed, WFQ considers discarding the new packet Normally, the newpacket is discarded If a packet with a larger SN has already been enqueued in adifferent queue, however, WFQ instead discards the packet with the larger SN! It’slike going to Disneyland, getting in line, and then being told that a bunch of VIPsshowed up, so you cannot ride the ride, and you will have to come back later.(Hopefully Disney would not take you out of the line and send you to the bitbucket, though!) In short, WFQ can discard a packet in another flow when thequeue for a different flow has exceeded CDT but still has lower sequencenumbers You can configure the CDT to a value between 1 and 4096, inclusive.Finally, WFQ can be configured for a maximum of 4096 queues, but interestingly,the actual value can only be a power of 2 between 16 and 4096, inclusive The IOSrestricts the values because WFQ performs a hash algorithm to classify traffic, andthe hash algorithm only works when the number of queues is one of these validvalues.

2.7.5 Class-Based Weighted Fair Queuing.

Like the other queuing tools with WFQ in the name, CBWFQ uses features thatare similar to some other queuing tools, and completely different from others.CBWFQ is like CQ, in that it can be used to reserve minimum bandwidth for eachqueue, but it differs from CQ in that you can configure the actual percentage oftraffic, rather than a byte count CBWFQ is like WFQ in that CBWFQ can actuallyuse WFQ inside one particular queue, but it differs from WFQ in that it does notkeep up with flows for all the traffic Many people find it difficult to keep thedetails memorized To help overcome confusion, the features of CBWFQ arecovered in the next several pages At the end of this section, some summary tableslist the key features and compare CBWFQ to some of the other queuing tools.CBWFQ supports 64 queues, with a maximum and default queue length of 64 All

64 queues can be configured, but one class queue, called class-default, is

automatically configured If the explicitly configured classification does not match