GarrettCom 6K25e manual Packet Prioritization, 802.1p QOS, Frame Buffering and Flow Control

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Magnum 6K25e Gigabit Fiber Switch

Installation and User Guide (10/07)

2.2.9Packet Prioritization, 802.1p QOS

Quality of Service means providing consistent predictable data delivery to

users from datagram paths that go all across a network. As a LAN device, the Magnum 6K25e can do its part to prevent any QOS degradation while it is handling Ethernet traffic through its ports and buffers.

The Magnum 6K25e switching hardware supports the IEEE 802.1p standard and fulfills its role in support of QOS, giving packet processing priority to priority tagged packets according to the 802.1p standard. In addition to hardware support for QOS, the MNS software (R2) supports two priority queues that can be shared across the eight levels of defined packet priorities for application-specific priority control by the user through software configuration settings.

2.2.10Frame Buffering and Flow Control

Magnum 6K25e’s are store-and-forward switches. Each frame (or packet) is

loaded into the Switch’s memory and inspected before forwarding can occur. This technique ensures that all forwarded frames are of a valid length and have the correct CRC, i.e., are good packets. This eliminates the propagation of bad packets, enabling all of the available bandwidth to be used for valid information.

While other switching technologies (such as "cut-through" or "express") impose minimal frame latency, they will also permit bad frames to propagate out to the Ethernet segments connected. The "cut-through" technique permits collision fragment frames (which are a result of late collisions) to be forwarded which add to the network traffic. Since there is no way to filter frames with a bad CRC (the entire frame must be present in order for CRC to be calculated), the result of indiscriminate cut- through forwarding is greater traffic congestion, especially at peak activity. Since collisions and bad packets are more likely when traffic is heavy, the result of store-and- forward operation is that more bandwidth is available for good packets when the traffic load is greatest.

When the Magnum 6K25e Switch detects that its free buffer queue space is low, the Switch sends industry standard (full-duplex only) PAUSE packets out to the devices sending packets to cause “flow control”. This tells the sending devices to temporarily stop sending traffic, which allows a traffic catch-up to occur without dropping packets. Then, normal packet buffering and processing resumes. This flow- control sequence occurs in a small fraction of a second and is transparent to an observer.

Another feature implemented in Magnum 6K25e Switches is a collision-based flow- control mechanism (when operating at half-duplex only). When the Switch detects that

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Contents Gigabit Fiber Switch Trademarks Canadian Emission Contacting GarrettCom, IncIntroduction Table of ContentsRevisions 6K25E Managed Fiber Switch Port ModulesMagnum Line Performance Technical SpecificationsNetwork Standards and Compliance, hardware Maximum 10 Mbps Ethernet Segment LengthsFiber Single-mode connector types Fiber Multi-mode connector types supportedManagement Console connector Power Supply InternalNebs Testing and Certification Nebs certified Alarm Contact OptionalPer-port MDI or Mdix on RJ-45 Agency ApprovalsOrdering Information 6K PoE Modules with 48VDC Pass-Through For Gigabit module configuration options6K PoE Modules with 48VDC Power Inside Introduction Inspecting the Package and Product Product Description Magnum 6K25e Managed Fiber SwitchWww . GarrettCom . com Eight-port SFF fiber modules 6K8-MTRJ, 6K8-MLC, 100Mb fiber Magnum 6K25e and 6K25eR chassis100Mb fiber eight Port modules for the MagnumEight-Port Copper Module, 6K8-RJ45 The 6K25e-Series’s8-port New PoEPower Inside, model PI6KP8-45RJ MDIX, 10/100Mb 8-port Per the IEEE802.3af PoE Four-Port 10 Mb mm Fiber ST Modules Gigabit 1000Mbps port modules Frame Buffering and Flow Control Packet Prioritization, 802.1p QOSWeb-browser, at ftp//ftp.garrettcom.com Managed Network Software MNS-6K for Magnum 6K25e-Series„ Managed switching for high performance Ethernet LANs „ Features Fiber-Built-In„ Nebs and Etsi tested and certified „ SFP Gigabit module being supported on Slot D „ RJ-45 ports are MDI/MDIX supportedApplications 6K 25e Locating Magnum 6K25e Switches InstallationConnecting Fiber Optic ST-type, twist-lock Connecting Ethernet MediaIeee Standard Media Type Max. Distance Port Module Fiber CopperConnecting Fiber Optic SC-type, Snap-In Connecting Single-Mode Fiber OpticMedia Ieee Standard Media Ieee Standard Gigabit SFP Small Form-factor Pluggable Optical Transceivers Side View Duplex LC connector Front viewSFP-SX SFP-LX10 SFP-LX25 SFP-ZX40 SFP-ZX70 Table-Top or Shelf Mounting1 Mountings for Magnum 6K25e units rack-mounted in a frame Rack-mounting for 19 Retma racks, regular Magnum 6K25esRack-mounting, Reverse version of the Magnum 6K25es Powering the Magnum Managed Fiber SwitchWww . GarrettCom . com 6K25e Port Module 6KPM Installation Preparation for Installing and Removing 6KPMsRemove Chassis Cover 1a Removing Chassis Cover Installing 6KPM Cards in the Magnum 6K25e Uplink 2f Securely latching up 6KPM Cards into a Magnum 6K25e Removing 6KPM Cards Connecting the Console Terminal to Magnum 6K25e Management Console DB-9 PortRemove 6KPM Card Switching Functionality Pin Signal DescriptionDB-9 Console port connector 1 RS-232 DB-9 Console Com port Serial port pin assignmentsUp-link MDI-MDIX on RJ-45 port modules, for port 1 only Status LEDsPWR ACTAuto-CrossMDIX and Auto-negotiation, for RJ-45 ports Flow-control, Ieee 802.3x standard F10ST Introduction Magnum 6K25e Managed Fiber Switch Port Modules 6KPM Module Description 1b 6KP4-F10ST, 4@10Mb multi-mode FX-ST twist lock Module 1c 6KP4 @10Mb @100Mb Multi-mode FX-ST twistLock Module Mode SC-type connectors. It Provides an advantage Mode 100Mbps fiber opticFiber functions in one Module of the 6K25e Switch Transceivers all in one module. ThisWww . GarrettCom . com Port@ 100Mbps Multi-Mode Fiber port Activity FULL/HALFLink Form Factor 9 6KP8-RJ45 Twisted Pair, 10/100Mb 8-Port Option in one 6K-unit Fig. the top 8-RJ45 PoE LEDs Summary10/100 GBIC-SXSC Gigabit fiber1000Mb, multi-mode SC Connector Before Calling for Assistance 14 6KM-BLNKReturn Material Authorization RMA Procedure When Calling for AssistanceShipping and Packaging Information No Problem FoundAppendix B Internal DC Power Supply Options Specifications for Magnum 6K25E SWITCHES, DC PowerB3.0 Applications for DC Powered Switches Magnum 6K25es. see figure at right B4.0 InstallationB4.1 UL Requirements for DC-powered units Appendix C Internal DC Dual-Source Power OptionB7.0 Troubleshooting B5.0 OperationC5.0 Installation C4.0 Features and Benefits of the DUAL-SOURCE DesignC6.0 Ordering Information C5.1 UL RequirementsExample Magnum 6K25eR-48VDC Example Magnum 6K25eR-24VDC or Magnum 6K25eR-125VDCOperation C7.0