5 Replies Latest reply on Feb 4, 2010 1:11 PM by wrightju

    vlan problem


      I have problem about the use in vlan .

      I thought the minnum length of  ether packet should be 64Bytes and when captured in Wireshark the FCS is cut.And it will be 60Bytes.


      When I set vlan with vconfig,the ARP packets seems to 60bytes(with TAG).
      And I thought it should be 64bytes since it has VLAN TAG.


      And the ARP packets in length 60 seems to be thrown by the NIC of the receiver.


      My English is not very well and hope I've explaned the problem clearly.


      The NIC in use is with chip Intel 82573L.


      I have used Reltak NIC to do the same thing.And had the same result.(ARP packet is 60Bytes with VLAN TAG)

      And I changed the source in if_vlan.h to make the packet to be 64Bytes.And succeeded.(I used Linux kernel 2.6.18)


      But it seems have no effect with Intel NIC.

        • 1. Re: vlan problem



          I'm not sure what could be causing that issue.  Would you be able to send me your WireShark capture file?  I'll send you a private message with the location to upload the file.



          Justin Wright

          Intel Corp.

          • 2. Re: vlan problem

            Thanks a lot for your reply.

            I've posted the packet trace file (a_rice.zip) to the ftp site.

            The broken ARPs is No.39 & No.40.

            I guess it was because the length of ARP packets is < 60bytes,so when NIC send them,the NIC
            pad them to 60bytes.But when VLAN is set, the packets should be padded to 64bytes.(And now they are also be padded to 60bytes.)
            I don't konw is my guess actually right and how to change it.Hope your suggestions.

            Thank you very much.

            • 3. Re: vlan problem



              I took a looked at the packet capture.  It definately looks like something is going on.  I will pass this along to our issue reproduction team, so they can take a look at it.  They will need some additional information so they can better reproduce your issue.  If you could answer the folling information that will help greatly.

              • What network driver version are you using?

              • What is the Make & Model of your system/motherboard?

              • What is the Make & Mode of you network switch?


              That should get us what we need to proceed with the issue reproduction.


              Justin Wright


              • 4. Re: vlan problem

                ##What network driver version are you using?

                root@mgsip:~# ethtool -i eth0
                driver: e1000★
                version: 7.3.20-NAPI
                firmware-version: 0.5-7
                bus-info: 0000:01:00.0
                ##What is the Make & Model of your system/motherboard?

                We don't have information about the system/motherboard.
                Instead, We have the following information.

                CPU・・・Intel Core2Duo T7400
                chipset・・・Intel E7520 + 6300ESB
                ##What is the Make & Mode of you network switch?

                This network switch's Make & Model is "IX2010" of NEC.
                "IX2010" is the router. We is using the NAT and IEEE802.1Q VLAN function.

                <network environment>
                add tagVLANpacket-->No tagVLAN packet

                [B] is not acceptable for IEEE802.1Q VLAN.
                So IX2010 needs remove/add tagVLAN packet.

                ※address information(example)
                [IX2010] ・・・



                • 5. Re: vlan problem

                  For the 82573L you should try our latest driver.


                  I'm wondering if the NAT might be causing the issue.  Could you test within the same network address range?