adrian.chadd Thu, 01/18/2007 - 22:02
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There's hardware in the 6500 design which handles packet classification and forwarding.

The supervisor CPU and routing CPUs aren't directly involved in forwarding packets. They instead look after programming the hardware with forwarding, QoS, ACL and routing information.

This means the hardware can do what its good at - forwarding packets - and the CPUs can handle running monitoring, housekeeping and switching/routing protocols without any impact on forwarding performance.

It does, however, mean the featureset can be somewhat restrictive compared to the software routers. You have to keep an eye on the hardware resource usage and do a little research before you enable features. Some features work in hardware (eg GRE decapsulation) except in certain circumstances (GRE hardware decapsulation requires the GRE endpoints to have unique IP addresses. If you terminate more than one GRE tunnel on a single IP address then it might be punted to the CPU for processing.)

HTH, please rate if you think it helped.

hermil Fri, 01/19/2007 - 12:05
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The answer not clarify my question ,i have seen 6500 with FWSM having the NAT or PAT capability data sheet HW-assistance . I want to know is this a limitation on product.

adrian.chadd Sun, 01/21/2007 - 16:14
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Aha, FWSM.

The platform uses hardware to implement functions traditionally found implemented in software. This means it achieves its advertised speed regardless of session count and connection rate. It does, however, put a pretty harsh upper limit on the parameters you can use.

Have a read of the datasheet, which covers the parameters.


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