Fermín Galán Márquez
2007-Apr-18 17:22 UTC
[Bridge] swithing trunk (tagged 802.1q traffic) with brctl
Hello, My name is Ferm?n Gal?n and I work as Research Engineer at CTTC, Spain. I'm trying to configure a bridge with brctl to switch VLAN tagged traffic (802.1q), but I'm getting some problems. In particular, I've a physical interface (eth2) connected to a Cisco trunk port (so, the traffic to/from eth2 is tagged). I've added eth2 to a bridge ('brctl addif somebrige eth2'), but it seems not being working for incoming traffic ('tcpdump -i eth2' doesn't shows incoming tagged traffic, but the traffic is being sent from the Cisco -I've checked it with port mirroring in the Cisco). I've performed some tests and the behaviour of VLAN in Linux seems to be as follows: when a tagged packet arrives to the interface, the kernel checks if there is some matching subinterface (for example, if the packet is tagged with VLANID=200, a eth2.200 is looked for). In that case, the packet is deliver (untagged) to that interface, otherwise the packet is discarted (so, it is never arrives to the bridge). Is that right? (I've asked this question also in the VLAN support list) Is there some way to change this behaviour (so unmatched tagged packages would be delivered to the bridge)? Any information or experience on the topic is very welcome. Thanks in advance! Best regards, -------------------- Ferm?n Gal?n M?rquez CTTC - Centre Tecnol?gic de Telecomunicacions de Catalunya Parc Mediterrani de la Tecnologia, Av. del Canal Ol?mpic s/n, 08860 Castelldefels, Spain Room 1.02 Tel : +34 93 645 29 12 Fax : +34 93 645 29 01 Email address: fermin.galan@cttc.es