Hello everyone,
I have gns3 set up with a bridge connection to a physical 3750 switch, the purpose is to send data with 802.1q tags from
VIOS or normal routers with subinterfaces to the physical switch. I am using a rj45 usb nic and i have enabled monitormode. (monitormode = some sort of nic option so it wont strip the 802.1q tags once they come inbound at the pc)
Packets going outbound from gns3 (so the tagged packets send from the virtual network devices) are okay and wireshark confirms that they are being send with a tag, but specifically tagged packets from the physical switch received at the PC show up with 'ipv4 total length exceeds packet length ' messages, dhcp requests from clients connected to the physical switch for example become malformed, ping replies send from the physical switch also become malformed.
the wireshark capture shows all the malformed data with a corruption of 4 bytes change, for example icmp ping with ipv4 total length 100, it shows the malformed packets with 'ipv4 total length exceeds packet length (96 bytes)'
I am getting an idea that the 4 bytes 802.1q tag has something to do with this. but even if i would set the pc mtu to 1600 i still get the same messages that the inbound received packets are malformed.
some important additional info, normal non dot1q traffic flows fluently, no problems whatsoever, and most importantly, tagged traffic like for example icmp with a max size of specifically 42 bytes also works (from virtual network devices to physical switch, with dot1q tag)
anyone have any idea/clue what the issue could be? i am planning on setting this up on linux since it natively has vlan support but this would be not ideal for me (lots of migration to linux would have to take place)
second edit: have some more info
No comments:
Post a Comment