"Dataplane does NOT need IOX"



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送交者: multithreaded 于 2005-4-01, 11:31:12:

回答: FYI: 对中国系统软件的思考(2)--给华为任正非和其他业务线领导同志的一封信((上) 由 osfab 于 2005-3-24, 12:08:27:

I agree with the author on the rest of analysis except for this one:

This SOC is very challenging engineering effort. However I don't think its complexity has nothing to do with IOX.

In general data plane code runs directly on the target. This is the fact to all NPUs I know (Intel IXP, Motorola C5, IBM etc.). In SSP it should run on top of 192 tensilica CPU. There is no RTOS type of SW running on these CPUs.

Even though I don't know how those NPUs are utilized, I beileve it is used in a PIPELINED mode. For example each cluster is for each application pipeline stage. In a word, pipeling is the key to high-performance in networking industry. The size of pipeline stage can be veried according to application needs.

Last but not the least important SSP seems only doing packet processing job, which is a relative easier one compared to other jobs done by the ASIC such as queueing and traffic management.

_______________________________________________

在HFR系统中,一个很重要的部件是一个新的ROUTING CHIP。这个芯片是非常有意思
的。一个有192个CPU CORE在一个DIE上。

请看TENSILICA的消息发布:http://www.tensilica.com/html/pr_2004_08_02.html
大家再来看一下CISCO的英雄,这个芯片的主设计师http://newsroom.cisco.com/dlls/innovators/
Core_IP/rajiv_deshmukh_profile.html

下面这个LINK也透露了一些技术细节。
http://www.eetimes.com/showArticle.jhtml?articleID=26806315

通过上述的一下信息,我们可以得出如下结果:
* NPU: From Tensilica Inc. www.tensilica.com
* Every 12 NPU being a Cluster.
* Every NPU with own L1 cache; A cluster shares L2.
* Total 16 Clusters /* 16*12 = 192 NPU */
* Packets are distributed into clusters.
* Two Extra Processor Core: One for Mgt; One for Debug
* Fabric: IBM .13
* Software Arch: Non pipeline based:-)
* Programming Approach: C/C++

从文章可知,这个芯片的名字叫SPP。TAPOUT回来是2002年的岁末。接近200个CPU
CORE的可编程网络处理器。读者不妨思考一下,在这个芯片上如何配置系统软件,
逻辑如何划分。各种TRADE-OFF折衷如何考虑。。。
这是一个非常艰巨的项目。要同时具有理论水平和实际经验。更为重要的是,要对
IOS的LEGACY方面了如指掌。





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