Download 356961: Internet Protocols - ECSE - Rensselaer Polytechnic Institute

Intel IXP1200 Network Processor
 Lab
12, Introduction to the Intel IXA
Jonathan Gunner, Sruti Gorappa, Kerry Wood
 Shiv Kalyanaraman
 Yong Xia (TA)
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[email protected]
http://www.ecse.rpi.edu/Homepages/shivkuma
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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First: What’s a Network Processor
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Router vendors have built speed into their devices by
pushing functionality down into hardware (ASICs).
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ASIC: Application Specific Integrated Circuits
They’re fast, but they’re custom-made for each
application and expensive to build.
Time to market for new implementations is extremely
long, since algorithms must be implemented at the
transistor/gate level.
Network processors look to avoid these pitfalls by
introducing specialized, software controlled devices
that can be customized quickly. But they also process
packets at near-wire speeds!
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Intel Internet Exchange Architecture
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Microengine technology — a subsystem of
programmable, multi-threaded RISC microengines that
enable high-performance packet processing in the data
plane through Intel® Hyper Task Chaining. This multiprocessing technology features software pipelining and
low-latency sequence management hardware.
The Intel IXA Portability Framework — an easy-to-use
modular programming framework providing the
advantages of software investment protection and faster
time-to-market through code portability and reuse
between network processor-based projects, in addition to
future generations of Intel IXA network processors.
Intel® XScale™ technology — providing the highest
performance-to- power ratio in the industry.
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Intel’s Gear (1)
IXP2850
 Designed for use in virtual private networks,
secure web services, and storage area
networks.
 IXP2800
 Able to handle line rates ranging from OC-48
to OC-192.
 IXP2400
 Designed for OC-12 to OC-48 network access
and edge applications.
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Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Intel’s Gear (2)
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The IXP 1200 product line represents Intel’s first
attempt in the area (it was actually inherited when they
purchased Digital)
The IXP 1200 is a single-board chip, designed with
abstractions in mind.
Since this is a new area, and it’s designed to be used
with many different types of hardware and software,
the documentation is incomplete/unavailable/or just
plain wrong.
To achieve wire-fast speeds with software, the goal is
to hide latency with parallelism. Processing packets is
inherently parallel, and necessary for fast applications.
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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How does the IXP 1200 simplify the ASIC
based design ?
A Typical ASIC Based Design
 A processor to handle routing information and
higher level processing
 ASICs to handle each packet
 An IXP 1200 Design
 StrongArm Core to handle routing algorithms
and higher level processing
 Microengines to handle packet processing
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Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Conceptually: Two Levels
The IXP1200 is designed to process packets at wire
speed, but also to handle control-plane information.
1. Strong ARM Core (1):
Designed
to handle control-plane and slow-path processing.
Update host tables, forwarding tables, filtering, running routing
protocols.
Runs an OS from a wide variety of sources (Linux derivatives /
VxWorks).
Has limited access to certain resources on board.
Development is done using
 WindRiver’s Tornado
 Embedded Linux
 ARM Software development kit
 C/C++
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Conceptually: Two Levels..
2. Micro Engines (6):
Data-plane
and fast-path processing.
Run no OS. Our model has a 2K instruction-store per microengine.
Multithreaded, 4 threads per engine.
Has access to all resources on board. Since there is no OS, and
these are virtually unrestricted, we must carefully avoid thread traps!
Microengine Development Tools
 Can write “microcode” or uEngine C
 Microcode Assembler
 Workbench
 Write symbolic microcode
 Assemble and optimize
 Transactor
 Debug and Simulation Engine
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Misc.
IX Bus:
Provides
interface to network ports, hardware shortcuts (like hardware
hash unit), super-fast and super-small scratch memory area.
StrongARM access to this is limited. It forces you to use the
microEngines when you really don’t want to.
Interface Devices
Intel
does not specify a type of interface to be used. These could be
ATM, Ethernet, FastE, GigE, wireless, etc.
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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IXP 1200 Building Blocks
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SRAM
 Store packet headers
SDRAM
 Store packet data
PCI Interface
 For accessing the control processor
Microengines and StrongArm Core make requests to
SRAM and SDRAM. The IX Bus and PCI Bus also make
requests to SDRAM.
Different type of queues for arbitration. Programmers can
choose the queues depending upon their requirements.
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Packet Flow Diagram
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Design Solutions
Enterprise Routers
 Streaming Video Server
 Manipulation of digitized video.
 Media Gateway
 Seamless transport of voice from circuitswitched to packet-switched networks
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Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Enterprise Router Line Card
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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16 Port Store and Forward Design
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Receive Threads (16)
 Receive packet from MAC port
 Verify IP Header
 Perform IP forwarding
 Place packet on transmit queue
Transmit Scheduler Threads (2)
 One per Microengine
 Determine which transmit queue has packets
 Assign work to each of three transmit threads
Transmit Threads (6)
 Three per microengine
 Send packet data to MAC port
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Rx: Lookup and Queuing
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Lookup the forwarding information in SRAM based on
header fields
Read the forwarding information from SDRAM
Modify the header and writes it to buffer in SDRAM
Write packet descriptor to SRAM
Lock Transmit Queue in SRAM
Enqueue packet onto the corresponding Transmit Queue
in SRAM
Set Port With Packets bit in scratch indicating that port
has packets
Unlock Transmit Queue in SRAM
Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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Tx
Transmit Scheduler
 Sequentially checks each port for data by
reading “Ports With Packets” in scratch
memory.
 Issues transmit assignments to the transmit
threads.
 Transmit threads.
 Lock the transmit queue, dequeue packet,
unlock queue.
 Move packet from SDRAM to TFIFO and set
TFIFO control bit.
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Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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For more info….
Jonathan Gunner ([email protected])
 Slide Contributions from Kerry Wood and Shruti
Gorappa
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Shivkumar Kalyanaraman
Rensselaer Polytechnic Institute
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