Network processors

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Network Processors are the Ubiquitous Word in Modern Day Routers . Network Processors process packets at a very faster rate. Eg., IP Packets have a Minimum 40 Bytes Packet Size, so at this size and at the rate of OC768 (aka 40 Gbps), it takes 8 ns to process a packet.

Network Processors are Processors which use very high streamlined/Pipelined Architectures. Proposal are there for superscalar parallel processing.

O.K., Whats the difference between My Computer Processor and a Network Processor ?

Well, Computer Processors are designed to operate/compute in an out-of-order computation manner. But, this isn't possible in Network Processors. Since, incoming packets can't be reordered and it can't be prefetched for later processing or for branch prediction.

So, Network Processors don't have Instruction Prefetch. Awk, that sounds too riddle.

So, how does it unique to a Computer Processor. Well,Network Processors are optimized and designed with Packet Processing in Mind.

It has the following uniqueness :

a) Network Processors are pipelined at the chip level. Every Instruction will be executed in Hardware Pipelined Thread Context. b) They are fabricated with Microengines. These Microengines process the packets with threads context and parallelized with common GPRs(General Purpose Registers),SRAM,DRAM and FBUS along separate buffers c) They have Host Controllers (eg., StrongArm Core) for Host Interfaces (eg., OS,User Interfaces) d) No Out-of-ordering and Branch Predictions.But have Hardware Storages like TCAM and use high efficient Compression Algorithms for Forwarding Tables and Classification Tables

Opertions by Network Processors :

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1) Network Processors Operate at Wire Speed. So, this requires high designs like avoidance of head-of-line blocking,Sync-ups. 2) They have Traffic Performance Capabilities like Congestion Control,Classification of Packets,Marking of Packets. 3) They have internal logics like Treatment of Low Overhead Packets over high Overhead Packets. 4) They have operations at different Planes. Data Plane,where packets are processed at wire speed.Control Plane,where control of Processsing is carried out and interactions with Protocols. 5) Operate at one,two or more dimensional Forwarding Tables. 6) Manual Generation of Classification Tables in Hardware Storages or in Software.

Where is it Used ?

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1) ATM,DSLAM,HDLC,Ethernet,SAN,etc., 2) Core Routers and Edge Routers along with Diffserv Capabilities.

Products/Models Using/Developing Network Processors

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1) AgereDF for their DSLAMs using ATM/Ethernet 2) Cisco GSR (Core Router) 3) Cisco 3750 (stacked/non-stacked) 4) Juniper Routers 5) Nortel Routers 6) Xelerated X11/X10 Network Processors 7) IXP 1200/2400/2800/4200 Network Processors