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.Over WAN links, standard NCP requests and responses can result inperformance degradation due to the ping pong effect.As each stationwaits for a corresponding acknowledgment, the line is tied up and noother traffic is transmitted.The delay is further compounded when large files are transmitted onepacket at a time.Even small files require the exchange of numerouspackets to fulfill a request.The Packet Burst protocol can boost performance 10 to 300%,depending on factors such as memory, bandwidth, and file sizes.In NetWare 5, Packet Burst is automatically enabled at both thex workstation and the server.5-45IG 5-90 This document should only be used by a Novell-certified instructor.Revision 1.0If you think this document was pirated, call 1-800-PIRATES or 1-801-861-7101. Optimizing the Network and ServerPresentation NotesPacket Burst Protocold 5-11 (Figure 5-11: PacketBurst Protocol)Define Packet Burstprotocol.Explain how normal readsand writes occur.Discuss the performancegains that are possible whenusing the Packet Burstprotocol.In NetWare 4.11 and higher, the workstation clientExplain that Packet Burst isinstallation program automatically enables Packet Burstautomatically enabled.and the PBURST.NLM is now included in SERVER.EXE.In prior versions of NetWare, the network administratorhad to change parameters in the NET.CFG file on theworkstation and load an NLM at the server to enablePacket Burst.Revision 1.0 This document should only be used by a Novell-certified instructor.IG 5-91If you think this document was pirated, call 1-800-PIRATES or 1-801-861-7101.Network and ServerOptimizing the NetWare 5 Advanced Administration Instructor GuideHow the Packet BurstProtocol WorksThe Packet Burst protocol allows a client to issue a single read or writerequest for blocks of data up to 64 KB in size.The data is partitioned intopackets and these packets are transmitted back-to-back withoutrequiring individual acknowledgment.Burst Gap Time and Burst Window SizeThe Packet Burst protocol uses a burst gap time and a burst windowsize to determine how much data is exchanged per burst transaction.The burst gap time is a time delay requested by the client beforeindividual packets are placed back-to-back on the media.This gap timeis used to prevent fast servers from overrunning the client s buffers.The burst window size refers to the number of frames or packetscontained in a single burst.With the Packet Burst protocol, the number of packets in the window isvariable, up to a theoretical maximum value of 128 (64 KB divided by512-byte packets).The window size is also variable by workstation, depending on howmany buffers the workstation has available, and by the constantmonitoring of the line capacity by the Novell Client.The clientrenegotiates the parameters without user intervention.Dropped Packets RecoveryWhen network traffic is heavy enough that packets are dropped intransmission, the Novell Client decreases the window size to minimizepacket loss.Any packets that are lost are retransmitted individually; theentire burst does not need to be retransmitted.The Packet Burst protocol monitors dropped packets and retransmitsonly the missing packets.When Packet Burst-enabled servers or clientstransfer data to servers or clients that do not have Packet Burst enabled,the data defaults to normal NCP (one-request/one-response) mode.5-46IG 5-92 This document should only be used by a Novell-certified instructor.Revision 1.0If you think this document was pirated, call 1-800-PIRATES or 1-801-861-7101. Optimizing the Network and ServerPresentation NotesHow the Packet Burst ProtocolWorksThis is one area in which the Packet Burst protocol sDiscuss burst gap time andwindow technology differs from traditional sliding windowburst window size.protocols such as SDLC.The window size for the Packet Burst protocol can benegotiated between the server and the workstationwithout user intervention.This is another deviation from standard windowingDiscuss dropped packetprotocols.In standard windowing protocols, every packetrecovery.including and after the bad packet must be retransmitted.Revision 1.0 This document should only be used by a Novell-certified instructor.IG 5-93If you think this document was pirated, call 1-800-PIRATES or 1-801-861-7101.Network and ServerOptimizing the NetWare 5 Advanced Administration Instructor GuideThe Packet Burst ConnectionA workstation sets up a Packet Burst connection with a NetWare serverat attach/login time.Once established, the connection remains for theduration of the attachment.If the Novell Client fails to make a Packet Burst connection duringattach/login, it uses normal NCPs.By default, Packet Burst is enabledfor all workstations.Packet Burst is established individually for each connection to differentservers.As a result, a workstation running the Novell Client can beattached to a NetWare 5 server using Packet Burst and to aNetWare 3.12 server using a standard NCP connection.When Packet Burst is loaded, the Novell Client first determines whetherthe workstation has enough memory for the requested number of PacketBurst buffers.If sufficient memory is available, the client initiates aPacket Burst connection to the server.During this connection process, the Novell Client negotiates maximumburst sizes, just as it negotiates packet size, with each connected server.Once a Packet Burst connection is established between a workstationand a server, the NetWare workstation automatically uses the PacketBurst service whenever an application makes a read or write involvingmore than 512 bytes of data.Applications do not have to be PacketBurst aware.Modifying Packet Burst Protocol PerformanceIn previous versions of NetWare, Packet Burst had to be enabled both atthe workstation and at the server.In NetWare 5, Packet Burst isautomatically enabled.It cannot be disabled at the server, but it can bedisabled on individual workstations.5-47IG 5-94 This document should only be used by a Novell-certified instructor.Revision 1.0If you think this document was pirated, call 1-800-PIRATES or 1-801-861-7101. Optimizing the Network and ServerPresentation NotesHow the Packet Burst ProtocolWorks (continued)Explain that the PacketBurst connection occursautomatically.The network administrator can disable Packet Burst orDiscuss how to modifymodify some Packet Burst parameters at thePacket Burst protocolworkstation.performance.Revision 1.0 This document should only be used by a Novell-certified instructor.IG 5-95If you think this document was pirated, call 1-800-PIRATES or 1-801-861-7101
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