Date: Tue, 05 Nov 2002 09:00:59 -0800 From: "Jacob S. Barrett" <jbarrett@amduat.net> To: "Jacob S. Barrett" <jbarrett@amduat.net> Cc: freebsd-net@FreeBSD.ORG Subject: Correction: VLAN tag byte swap and chop problem?? Message-ID: <3DC7F94B.2020606@amduat.net> In-Reply-To: <3DC7F88B.8090602@amduat.net> References: <3DC7F88B.8090602@amduat.net>
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Line: It shows the frame leaving as vlan 2 (0x0020) (correct) ... Should read: It shows the frame leaving as vlan 2 (0x0002) (correct) ... Sorry, Jake Jacob S. Barrett wrote: > I am not sure if I am doing something completely wrong of if I have > found some sort of bug here, but I thought I would toss it out to see if > anyone else has ever seen this. > > I have two ports on my switch configured for vlan id 5. Port 1 is > untagged and port 2 is tagged. The machine A is on port 1 and machine B > is on port 2. Machine B's card is configure with multiple vlan nodes > attached to it, including vlan id 5. I couldn't ping B from A so I > attached tcpdump to the parent interface on B to see what was happening. > So here is the strange part. The arp request from A to find B says > that it is on vlan 1280. So I set the vlan id on the switch to 1280 and > tcpdump says 5. So, id 0x0005 on the switch becomes 0x0500 on the host > and 0x0500 on the switch becomes 0x0005 on the host. So I thought maybe > a byte order problem until I tried setting the id on the switch to 18. > So the id on the switch was 0x0012 and tcpdump reported it on vlan > 0x0200. Trying other vlan IDs shows the same behavior. The id on the > framed that is delivered is byte swapped with the first nibble chopped > off. > > 0x0005 -> 0x0500 > 0x0500 -> 0x0005 > 0x0002 -> 0x0200 > 0x0200 -> 0x0002 > 0x0012 -> 0x0200 > > Here is my tcpdump from machine B (.1). Machine be is attempting to > ping machine A (.2). It shows the frame leaving as vlan 2 (0x0020) > (correct) and the reply coming back from A on vlan 512 (0x0200). > > 11:35:16.982435 802.1Q vlan#2 P0 arp who-has 10.126.0.2 > (2e:2f:30:31:32:33) tell 10.126.0.1 > 11:35:16.982593 802.1Q vlan#512 P0 arp reply 10.126.0.2 is-at > 0:90:27:f4:3c:9f > 11:35:17.992434 802.1Q vlan#2 P0 arp who-has 10.126.0.2 > (2e:2f:30:31:32:33) tell 10.126.0.1 > 11:35:17.992604 802.1Q vlan#512 P0 arp reply 10.126.0.2 is-at > 0:90:27:f4:3c:9f > 11:35:19.002467 802.1Q vlan#2 P0 arp who-has 10.126.0.2 > (2e:2f:30:31:32:33) tell 10.126.0.1 > 11:35:19.002627 802.1Q vlan#512 P0 arp reply 10.126.0.2 is-at > 0:90:27:f4:3c:9f > > So does anyone have any ideas? I am assuming this is either a > configuration issue on my part with my boxes or a bug in the vlan code > for if_em. I doubt that it is a problem with the switch firmware since > this came from a production site where vlans were used extensively. > Also, it correctly transmits the frame on the ports tagged for that > vlan. My guess is that it is in the if_em driver somewhere. If anyone > wants to tackle this let me know. > > Hardware Involved: > (1) Extreme Networks Summit 4 > (2) HP LPr Dual PIII 600MHz > (1) Intel Pro 10/100B/100+ Ethernet > (2) Intel(R) PRO/1000 > > -Jake > -- Jacob S. Barrett jbarrett@amduat.net www.amduat.net "I don't suffer from insanity, I enjoy every minute of it." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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