FCTracer 4G

Fibre Channel provides a bi-directional, physical or logical point-to-point, low latency connection between two devices at a time.  Like other serial interfaces such as Serial Attached SCSI (SAS), in Fibre Channel data is transmitted over the physical medium in serial fashion as opposed to parallel methods, which are used in SCSI and ATA physical interfaces. Serial transmission enables much longer connection distances as compared to parallel transmission methods, because far fewer signal lines are required, thereby reducing noise created by multiple signal lines all switching at the same time (cross talk).

A primary use for Fibre Channel is in the transport of block oriented storage traffic in SAN (Storage Area Network) applications. There are also specialized upper layer Fibre Channel protocols that are used in Defense and Avionics applications, to transport video streams for heads-up displays, for example.

Fibre Channel is designed to work with either optical fiber physical medium or copper cables in many connector and cable type configurations.  Copper cables are relatively inexpensive, but they are useable only for shorter distances, in the range of 10 meters maximum. In general the higher the transmission speed, the shorter the distance that can be reliably supported by copper cable technology.  A variety of copper solutions are available, the most commonly used being copper SFP (Small Form-factor Pluggable) or more recently SFP+ copper cables. SFP and SFP+ optical cabling solutions are also available, supporting reliable transmission distances greater than 10 meters, up to about 10 kilometers.

Fibre Channel is a layered protocol, and is modeled loosely on the OSI model for networks. In the OSI model, and in the case of Fibre Channel, each layer provides specific services and makes the results available to the next layer.  Figure 1 below compares the defined OSI layer to the defined Fibre Channel layers.

Figure 1, OSI Model and Fibre Channel Network Layers

The layers in the table represent different functions and services that exist within the Fibre channel protocol definition. As with the other communication standards, protocol level analysis is often focused at the link layer (FC-2) and above.

Fibre Channel, like any network architecture, transports blocks of user or application related information called payloads. Before sending a payload over the physical link, additional Fibre Channel specific control bytes are added to both the start and the end of the payload data. The combination of the control bytes and the payload data is called a frame, which is the basic unit of information in Fibre Channel.  A minimum of 60 bytes of overhead data surround each frame for the purposes of maintaining minimum separation between frames, mark the start and end of a frame, and to check for transmission errors. Within a frame the actual user data being transported can vary from 0 to a maximum of 2112 bytes. Fibre Channel transfers data through switched or direct point-to-point connections which work by creating temporary connections between the source and destination devices.  These connections last only until the transfer is completed and can be temporarily preempted by higher priority transfer requests.

Connections are made on Fibre Channel systems through “interconnect components” such as switches, hubs, and bridges. The ability of Fibre Channel to use different interconnect devices makes it flexible and scalable depending on user needs. For small Fibre Channel networks, inexpensive hubs and loop-switches may be used for connecting devices in a topology called Fiber Channel Arbitrated Loop (FC- AL). As Fibre Channel networks get larger and network bandwidth demands increase, full matrix switching may be implemented. A fully switched Fibre Channel network is called a Fabric topology.

Fabric topology permits multiple alternative paths to be established between any two ports in the Fabric. Loop (FC-AL) topology, on the other hand, is like a string of Christmas tree lights where the path goes serially from one device to the next and finally back to the originating device.  In this type of topology if one device or the path between any two devices fails, the entire string of devices lose their connection.  Loop and Fabric topologies can be combined to provide both low cost connectivity and high performance.

Fibre Channel protocol is designed to support very low latency and high data transfer rates. The currently approved standard supporting up to 8.5Gb/s, is generally referred to as 8GFC. Server virtualization and storage virtualization are broad trends that are driving the need for higher bandwidth.  The need for high bandwidth in the network infrastructure is just now beginning to drive the replacement of previous product generations of 1, 2, and 4GFC by 8GFC.

Fibre Channel is a good choice for any environment with many servers needing access to centralized storage, computer data centers for example. Because of this, Fiber Channel enjoys over 80% market share as the network interface used in external storage systems such as SAN environments.

LeCroy's FCTracer is a portable 4, 2 and 1 Gbps Fibre Channel test and debug platform that combines non-intrusive, multi-port recording with the most advanced triggering and decoding features available. By leveraging years of experience in protocol analysis tools for emerging markets, FCTracer fibre channel protocol analyzer blends sophisticated functionality with practical features to allow designers and validation engineers to easily specify multi-level, conditional trigger scenarios to pinpoint intermittent problems in the Fibre Channel fabric. With Fibre Channel SANs growing in size and complexity, interoperability issues between equipment from different vendors is often masked by fibre channel's built-in error recovery features. LeCroy meets this analysis challenge with a new breed of test tool designed to isolate intermittent problems in the lab or field. FCTracer's ability to characterize Fibre Channel traffic across multiple links and over extended periods makes it the ideal tool for end-to-end testing of live SANs. The CATC Trace™ Protocol Analysis software adds an easy to understand display that shows traffic in the context of the fibre channel protocol.

• 2 Parallel Event Sequencers with 256 States, each with Independent Trigger & Filter Criteria - Isolate intermittent problems by tracking two completely independent event sequences in parallel
• Two or Four 1, 2 and 4 Gbps FC Ports - Monitor, trigger and record multiple Fibre Channel ports simultaneously
• Link Tracker™ Trace Display - Chronologically display all DWORDs on all channels synchronized to a common clock
• Hardware Filtering - Extend capture window by removing non-essential primitives or truncating data payloads from the trace
• Performance Statistics - Quickly identify and track error rates, abnormal bus or timing conditions
• Long Term (Spooled) Recording - Enable capture of intermittent problems for which trigger conditions are difficult to predict
• Cascade Multiple Analyzers - By cascading up to 4 analyzers, time correlated traces for up to 16 channels can be obtained
• Remote Access over LAN - One or more FCTracers can be controlled over the network
• Traffic Summary Reports - Statistical summaries provide high level abstraction of events, sequences, exchanges, errors and throughput
• Collapsible / Expandable Headers - Increased drill-down on Exchanges, Sequences, or individual Frames
• Automatic FC-2 and FC-4 Level Decoding - View FC Traffic in context of the Fibre Channel protocol
• Field upgradeable BusEngine Protocol Processor - Real-time triggering and filtering of Fibre Channel traffic at full wire speed
• Real-time Performance Monitoring & Statistics - Easily identify throughput problems and anomalies
• Dynamically Allocated Memory Pool - (2 GB) captures long time-windows for analysis and problem solving
• Verification Script Engine - Create custom scripts that automatically parse trace files and perform verification tasks
• FC-Auditor™ post processing suite - Optional software can automatically perform architectural compliance assessment on the contents of a trace file

The LeCroy FCTracer Protocol Analyzer is a hardware plug-in module that installs into the CATC Protocol Analyzer System (CATC 10K platform). The FCTracer ensures both accurate data collection and transparency on the link by recording traffic using active port bypass circuitry. SFP modules are used to ensure wide compatibility with various media types. A USB 2.0 connection is used to control the FCTracer hardware and provide high-speed upload of captured data. With the ability to control the analyzer over TCP/IP networks, you can remain productive in your own work areas while capturing trace data remotely.

The heart of the FCTracer Analyzer is LeCroy’s state-of-the-art BusEngine™ technology. The revolutionary protocol processor core incorporates both a real-time recording engine and configurable tools to trigger and filter high-speed Fibre Channel traffic. Fully field-upgradeable, this sophisticated analysis hardware is capable of recording millions of Fibre Channel frames in only seconds.

FCTracer's memory controller dynamically allocates memory resources up to a maximum 2GB across all four recorded channels. You can selectively exclude any channel from the recording to boost memory depth for the remaining channels. Set the post trigger buffer to determine where in the recording the trigger is located. FCTracer also offers a manual trigger button. External BNC connectors are available for cascading multiple FCTracer analyzers or for trigger in/out to other test instruments. A break-out board is included that can store out of band signals along with the recorded trace.

LeCroy's advanced analysis software automatically decodes network traffic and problems. For every trace, LeCroy's software generates high-level views and traffic summaries that help point out where protocol violations occurred. It actually detects and alerts you to problems at all functional levels of the Fibre Channel layering including:

• FC-1: Invalid CRC; running disparity error, invalid 10bit codes
• FC-2: Frame, sequence and exchange violations
• FC-4: FCP mapping and SCSI errors

The CATC Trace display system is the de-facto industry standard for advanced protocol analysis. While other products display the stream of packets in difficult-to-understand text format, the CATC Trace matches a strong decoding engine with an easy to use graphical user interface that removes complexity and trains the eye to understand more information faster. LeCroy's analysis software displays each Primitive, Data Frame, or decoded Sequence on separate rows with every field labeled and verified for proper formatting.

Caption Colors and graphics are used to represent Sequences, Exchanges or individual Frames in the context of the Protocol. You can rapidly identify the area or operation of interest and then click to expand its contents. For deeper analysis, you can view packet contents as raw 10-bit codes.

For efficient testing and deployment of Fibre Channel networks, an analyzer has to let you extract useful information from a crowded stream of traffic, and accurately identify and selectively record what interests you most. With FCTracer software, setting complex recording, triggering and filtering options is easy and powerful.It's the first protocol analyzer offering two independent sequencers that can track two unrelated series of events in parallel. Almost like having two analyzers in one - Each sequencer can separately monitor up to 256 levels of trigger logic with up to six "events" per level. The triggering and filtering options are channel independent and can record different fields based on the traffic detected on the individual links. This powerful triggering and filtering model is particularly useful for trapping intermittent problems within live SAN environments.

FC-2 and FC-4 level events - allow you to choose from a library of predefined packet types including basic and extended link-services; SCSI operations; or primitives. Custom recording templates - allow you to predefine and reuse custom trigger/filter settings within a development team. Sequencers - allow you to create multiple sequential trigger scenarios that can each operate independently across multiple channels. Counters - allow you to further qualify recorded traffic by tracking multiple occurrences of specific events, frames or sequences. Timers - allow you to employ time-based thresholds to initiate actions including starting subordinate sequences, restarting counters and starting/stopping the recording.

FCTracer automatically decodes FC operations and helps developers to focus on the information that is most important to your own specific environment. At the Sequence level, FCTracer decodes Basic and Extended Link Services, GS-3 management server transactions, and FCP operations. The Exchange level intelligently groups sequences that are part of a common exchange for easy identification. By accurately interpreting upper level protocols, you can focus on solving problems instead of spending time looking up information in the Fibre Channel Spec. By grouping Frames logically within your related sequences and exchanges, you are free from reconstructing FC-4 level operations in your head. Automatic decoding of FC-SW-3 and FC-Tape protocol improves debug of Switch-to-Switch Traffic or FC connected Tape storage systems. LeCroy's Fibre Channel protocol analyzer also offers a file-based scripting mechanism that can be modified with any text editor to display vendor-defined content or call out special payload elements to suit a specific development need.

Today's SAN technicians face intermittent problems that may be traced to incompatibilities or configuration problems in the SAN. In these situations, it is very hard to predict the trigger conditions or isolate the problem event using traditional analysis techniques. With spooled recording, the Fibre Channel protocol analyzer can be deployed at strategic points in the SAN and record unprecedented level of detail about traffic moving through the network over extended periods. The system can actually capture time stamped trace data for I/O operations that occur over several hours or even days. In this recording mode, the size of the trace is limited only by the amount of available storage space. FCTracer v2.0 can now report traffic metrics across spooled "segments". The advanced search and timing calculator can also span across spooled files.

Fibre Channel's high data rate makes the ability to selectively capture the important traffic critical. With real-time filtering of primitives or user definable frame types, FCTracer preserves recording memory and allows you to focus your analysis on the essential Fibre Channel traffic. FCTracer also uses a compression algorithm to store redundant primitives for even further reduction of trace memory requirements. The additional Link Tracker display allows you to see DWORD level bus traffic in a table view. This simplifies analysis of state transitions by displaying the Fibre Channel traffic, moving across all channels, synchronized to a common reference clock. Link Tracker may be used independently or time synchronized with the CATC Trace display. Powerful search options allow you to find any primitive, or header field in the trace. Many of the most useful searches have already been indexed during upload. "Point and click" tools allow hiding of virtually every element within a trace including primitives or traffic from individual channels. As display options are customized, it's easy to save them to a configuration file and share within a development team.

FCTracer includes many mechanisms to measure and report on Fibre Channel traffic. For each sequence, you can see an absolute time-stamp, time-delta between sequential time-stamps, or idle time between packets on the same link. You can specify whether the timestamp is displayed in nanoseconds, microseconds, milliseconds, or seconds. The FCTracer's Traffic Summaries provide statistics on the occurrences of errors, primitives, frames, sequences, and exchanges. You can evaluate these metrics at a glance or use them to navigate through the trace. FCTracer also features graphical bus utilization and throughput reports, which provide a histogram of activity dynamically linked to packet level details. The FCTracer Timing and Bus Usage Calculator provides various throughput and performance metrics on a user-specified subset of the trace.

The LeCroy Verification Script Engine (VSE) is a documented API that allows custom scripts to programmatically extract information from an FCTracer recording. You may use it to create "automated analysis" tests that open and parse actual trace files. The scripting language can perform very complex and tedious calculations on large trace recordings. In only a few moments, scripts can be created that automatically determine:

• Maximum Exchange Completion Time
• Average time between CMD to XFER_RDY
• Count "Out-of-Credit during Tenancy" events for any source/destination

LeCroy's VSE technology also includes a communication framework, which allows pass/fail results to be exchanged with third party applications.