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Date: Sun, 25 Jun 1995 07:28:21 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199506242128.HAA01653@godzilla.zeta.org.au>
To: davidg@Root.COM, nc@ai.net
Subject: Re: FreeBSD as a router
Cc: hackers@freebsd.org
Sender: hackers-owner@freebsd.org
Precedence: bulk

>Second question, and related. Even if an software based router has to 
>wait for an entire packet frame to come in before routing it, that 
>strikes me only as a latency problem, and not a thruput problem, 
>especially on cards that can multitask and have builtin buffers [32k in 
>the SMC 100mbps I believe] Couldn't the driver be written to grab the 

This seems rather small.  4K buffers cause problems at 10Mbps so I
suppose 40K would cause problems at 100Mbps.

>entire contents of the buffer and route them all the packets at once? I 
>can't imagine that a 486 or a Pentium is slower in horsepower than a 
>Cisco box, even though a cisco may be able to turn them around faster. 
>Actually, if memory serves, the clock interrupt hits many times a second. 
>In BSD I think rtc0 is about 100 times per second. With a 32k buffer 
                clk0
>polled once per tick, you are getting MUCH higher thruput than 
>100megabits assuming you are on a PCI bus [scratch the 486 in that 

Much lower.  32K * 100 * 8 is only 24Mbps.  100Mbps is a lot.

Bruce