Date: Tue, 1 Feb 2000 22:48:59 -0700 From: "Kenneth D. Merry" <ken@kdm.org> To: freebsd-net@FreeBSD.ORG Subject: anyone know about 802.3x flow control? Message-ID: <20000201224859.A38780@panzer.kdm.org>
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I've got an Intel 410T standalone switch for my home network: http://www.intel.com/network/products/exp410t.htm I've got four machines hooked to it, which have: Card Speed Driver no-name DEC 21140A 100Mbps, full duplex de SMC 8216 10Mbps, half duplex ed Intel 82559 100Mbps, full duplex fxp HP JetDirect 100Mbps, full duplex (it's a printer) Everything works fine, but I noticed something odd on the machine with the Intel ethernet board tonight. It was getting tons of packets every second (several screens full) from the switch. The packets looked like this in tcpdump: 22:15:53.313742 0:0:0:0:0:10 1:80:c2:0:0:1 8808 60: 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 22:15:53.355673 0:0:0:0:0:10 1:80:c2:0:0:1 8808 60: 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 8808 0001 0000 0000 The last octet of the source hardware address changes based on what port in the switch I'm plugged into. (It's in port 10 now. If I plug it into say port 11, it'll be 0x20, 12, 0x30, and so on.) I ran tcpdump on the other two FreeBSD boxes (with the SMC and DEC cards), and didn't notice any packets like that. So my guess was that it must be some autonegotiated parameter between the switch and the card that caused that to happen. So I went into the switch configuration menu (via the serial port) and disabled flow control on port 10. The packets above stopped. Now, occasionally (once every minute or two, maybe?) I get packets like this: 22:40:13.958917 ff:ff:ff:ff:0:90 2:0:0:0:ff:ff 27d1 322: 7776 0800 4500 0130 cf09 0000 4011 95b3 0a00 0002 0a00 00ff 0201 0201 011c 4e86 0101 0000 3897 c33d 0000 0000 7061 6e7a 6572 0000 0000 I assume the above storm of packets was due to the "IEEE 802.3x standards-based flow control." that the switch supports, but what I don't understand is why the packets kept coming. Is this something that the card is supposed to intercept somehow and deal with, or is it something that the OS is supposed to intercept and deal with? I'd guess the latter, but I'd like to know more about it, and perhaps why my switch kept spewing. (Naturally, Intel's web site didn't have much helpful information that I could find.) Anyone know anything about this? Thanks, Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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