Emil Micek wrote:
Hello list,
I've got a Linux router with 2 NICs:
- eth0 is external interface connected to Internet, lspci reports it as
01:08.0 Ethernet controller: Intel Corporation 82801DB PRO/100 VE
(CNR) Ethernet Controller (rev 82)
- eth1 is internal interface connected to our local network, lspci line
looks like this
01:0c.0 Ethernet controller: Intel Corporation 8255xER/82551IT Fast
Ethernet Controller (rev 10)
Now i want to do VLAN tagging of internet traffic passing through the
router, so i created VLAN interface eth1.101 with IP 10.146.154.62
(our local network has 10.146.154.0/26 adress range).
Everything is working fine except small packets.
Minimal ethernet frame cannot be shorter than 64B (according to the
specification). If the payload of the frame is not big enough, the frame
is padded with random data to 64B. If such padded frame arrives to our
router, the padding is removed, the VLAN ID tag is added and the frame
is sent to our local network without the padding added back, resulting
in frame smaller then 64B. Such frames are then discarded by our cable
modem equipment located in our local net.
I believe NICs are supposed to pad small packets, even though it might not show in ethereal
(on the VLAN machine).
Is this sniff from the router itself or from an external system?
Ben
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
_______________________________________________
Vlan mailing list
Vlan@xxxxxxxxxxxxxxx
http://www.candelatech.com/mailman/listinfo/vlan
