Date: Fri, 6 Apr 2001 09:23:30 +0200 (CEST) From: Harti Brandt <brandt@fokus.gmd.de> To: Richard Hodges <rh@matriplex.com> Cc: Alex Huppenthal <alex@aspenworks.com>, <freebsd-atm@FreeBSD.ORG> Subject: Re: ATM 4.3 and so on Message-ID: <Pine.BSF.4.33.0104060920090.29091-100000@beagle.fokus.gmd.de> In-Reply-To: <Pine.BSF.4.10.10104050937080.45890-100000@mail.matriplex.com>
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On Thu, 5 Apr 2001, Richard Hodges wrote: RH>On Thu, 5 Apr 2001, Harti Brandt wrote: RH> RH>> On Wed, 4 Apr 2001, Richard Hodges wrote: RH>> RH>> RH>The third would be suitable for filling a DS3 (96000 cells/s), and the RH>> RH>fourth could carry 10 mb/s of user data. Keep in mind that this is per RH>> RH>VC, so if you have many going at once, you may still exceed your cell RH>> RH>rate. I believe that the Fore card expects this rate info in network RH>> RH>byte order, but if not, just remove the "htonl()" from the macro. There RH>> RH>are many more possible values; let me know if you want the rest. RH>> RH> RH>> RH>And I haven't tested this myself, so if you give it a try, please let RH>> RH>us all know how it works :-) RH> RH>> For what I know, this works only for a single VC. As soon as you try to RH>> shape more than one VC, things go wrong. Three years ago a Fore engineer RH>> told me, that they are going tu support shaping of up to 32 VC's 'in the RH>> Windows driver'... :-( RH> RH>Well, that ^h^h^h^h^h is not good. From the rate control values, it RH>did look like some kind of burst/skip system. Both values add up to RH>255. Could it be that the rate is actually the entire interface rate RH>while that PDU is sent? That would make it complicated to handle RH>multiple VCs, but not impossible. Unfortunately, the cell spacing RH>would probably still be a problem. The problem is the scheduler in the firmware. If it finds a output packet with a non-zero rate specification it starts to transmit that packet at the specified rate and all other packets wait until that one is finished. Well, perhaps it can even put following unspecified packets in between, but it can't handle two packets with shaping at the same time. I don't know, what the latest firmware version is. Perhaps they did something about it. RH>I think I will stick with the ForeLE (IDT) cards. Do they have the same API? harti -- harti brandt, http://www.fokus.gmd.de/research/cc/cats/employees/hartmut.brandt/private brandt@fokus.gmd.de, harti@begemot.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-atm" in the body of the message
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