From: Howard C. Berkowitz (hcb@gettcomm.com)
Date: Mon Dec 29 2003 - 11:22:20 GMT-3
At 1:22 PM +0800 12/29/03, Pun, Alec CL wrote:
>Shahid,
>You are correct, even a cat 4500 doesn't support NAT as well. I think
>that's possible for 6500.
>
>rgds,
>alec
I suspect this is a basic architectural issue with the "switch"
products. On things such as the 7500, we can speak roughly of a
"fast" and a "slow" path. The fast path, from the standpoint of the
main processor, is principally in the forwarding engines, and the
main processor just feeds them routes. The slow (forwarding) path is
in the main processor, and is used for features like NAT, complex
QoS, and other functions that need extensive processing and buffering
before forwarding can occur.
One of the differences between the "switch" and "router" products is
that the slow path, in the routers, tends to have more processor
power, and, very significantly, buffer memory. Even at the high end,
good practice with the 12000 puts it in a provider core, with things
like filtering, QoS, and NAT done by other routers in the
distribution tier.
In contrast, I understand that Juniper does not distinguish between
fast and slow path, so performamce tends to degrade more gradually
when additional features are enabled. With no direct experience, I
suspect that products from a primarily "switch" company such as
Extreme tend to be like Cisco switches, but more so. At one point,
they were reported to have a problem with large number of BGP routes.
Again at one point, the Nortel Passport 8600 was memory limited for
some applications, while the Contivity "high touch" products had much
more processing and memory resources.
>
>
>-----Original Message-----
>From: Shafi, Shahid [mailto:sshafi@qualcomm.com]
>Sent: Monday, December 29, 2003 1:06 PM
>To: ccielab@groupstudy.com
>Subject: NAT Support on 3550?
>
>
>Hi Guys,
>
>I am surprised to find out today that 3550 doesn't support NAT. Is is
>ture or I am missing something? Cant believe it!!
>
>Thanks
>Shahid
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