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Date:      Sat, 16 Oct 1999 13:25:23 -0500
From:      "Jimbo Bahooli" <griffin@blackprojects.org>
To:        "Mike Smith" <mike@smith.net.au>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: Balancing Outgoing traffic over 2 nics, and nic limitations.
Message-ID:  <199910161325230440.0DE208AE@207.109.8.249>
In-Reply-To: <199910161735.KAA06493@dingo.cdrom.com>
References:  <199910161735.KAA06493@dingo.cdrom.com>

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On 10/16/99 at 10:35 AM Mike Smith wrote:

>> Hello my FreeBSD friends.
>> 
>> I have two issues.
>> 
>> The first is how to balance outbound traffic over 2 nics that are on
>> the same subnet.  Example configuration:
>>
>> fxp0: 12.2.2.5 netmask 255.255.255.0
>> fxp1: 12.2.2.6 netmask 255.255.255.255
>> 
>> router at: 12.2.2.1
>
>
>You can't do this.  If all of the outbound traffic is headed for the 
>same router, put two cards in the router and use two separate nets.
> 
>> Currently I have the obvious static route to 12.2.2.1, which locks
onto
>> fxp0 so all outbound traffic flows out over that link.  Inbound
traffic
>> balances per ip as I would expect.  I hope to find a scalable
solution
>> as I hope to build a server that will utilize 3 nics.
>
>This is not a sensible course of action.
>

Sounds fair. :)

>> This configuration is neccessary because by my estimation I have run
>> into a limit on the intel pro 100 netcards of 6,000 packets/second.
>
>These cards do not exhibit such a limit.  You may have run into some 
>issues with FreeBSD's ability to handle very large numbers of small 
>packets with your particular application mix.
>
>> This limit equates to about 30 to 32 megabit/second of web traffic
in
>> our situation.  I am wondering if anyone else has noticed this
limit?
>
>Not in my recollection.  The fxp driver in recent incarnations limits 
>the number of interrupts it generates by restricting them to 
>low-resource conditions rather than generating one per packet.  And 
>I've personally seen an SMP kernel run tolerably while taking >
100,000 
>interrupts per second.
>
>> This limit was hit on 2 very different machines, one with
significantly
>> less power.  Any feedback on either of these issues would be
>> appreciated.
>
>I'd start by eliminating the network adapter and driver; move to an 
>up-to-date FreeBSD-stable and substitute a 3C905B or C and determine 
>for yourselves whether this is really an issue with the card.
>
>General experience would suggest that you should be able to come close

>to saturating your network with even relatively small datagrams using 
>either of these adapters.
>
>You also don't mention whether you're running on a switched network;
at 
>that sort of traffic level you will definitely want to be using a 
>switch that supports full duplex operation.

Of course its a switched network with full duplex operation.  But now
that the general answer is that it is not a limitation of the nic card
I am going to look elsewhere.  I was not to sure if it was actually a
limit myself, its just that I observed it on two different machines.
They however were not huge powerhouses, one was a p2-450, and one was a
dual p2 333.  Both running real new versions of 3.3-stable.  

Thanks for the replies at any rate.




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