To clarify the behaviour of open vswitch: With either of the native modes selected, a packet that comes in to the switch without a vlan header will be placed in the native vlan and the header added before the packet is forwarded. With nativeMode='tagged', a packet in the native vlan will be sent out of the switch with its vlan header intact. With nativeMode='untagged' a packet in the native vlan will be sent out of the switch with the vlan header removed. In case it helps, here is the open vswitch doc for the vlan settings: Bridge ports support the following types of VLAN configuration: trunk A trunk port carries packets on one or more specified VLANs specified in the trunks column (often, on every VLAN). A packet that ingresses on a trunk port is in the VLAN specified in its 802.1Q header, or VLAN 0 if the packet has no 802.1Q header. A packet that egresses through a trunk port will have an 802.1Q header if it has a nonzero VLAN ID. Any packet that ingresses on a trunk port tagged with a VLAN that the port does not trunk is dropped. access An access port carries packets on exactly one VLAN specified in the tag column. Packets egressing on an access port have no 802.1Q header. Any packet with an 802.1Q header with a nonzero VLAN ID that ingresses on an access port is dropped, regardless of whether the VLAN ID in the header is the access port’s VLAN ID. native-tagged A native-tagged port resembles a trunk port, with the exception that a packet without an 802.1Q header that ingresses on a native-tagged port is in the ‘‘native VLAN’’ (specified in the tag column). native-untagged A native-untagged port resembles a native-tagged port, with the exception that a packet that egresses on a native- untagged port in the native VLAN will not have an 802.1Q header. ________________________________________ From: sendmail [justsendmailnothingelse(a)gmail.com] on behalf of Laine Stump [laine(a)laine.org] Sent: 22 February 2015 19:31 To: Libvirt Cc: Robson, James Subject: Exact meaning of "nativeMode" attribute in vlan tags You'd think that I would know this, since I'm the person who reviewed jrobson's patch adding support for the nativeMode attribute to the vlan tag element. But you'd be wrong. Here is what the config looks like: <vlan trunk='yes'> <tag id='42' nativeMode='untagged'/> <tag id='47'/> </vlan> I understand that trunk='yes' means that packets with any of the tags listed in a <tag> subelement can be sent out this port (and the tag will *not* be removed), and likewise packets arriving into the bridge from the port are allowed to have any of the listed tags (and, again, no tag will be removed). But what exactly do nativeMode='untagged' and nativeMode='tagged' mean? As I understand it, (nativeMode='untagged'|nativeMode='tagged') means that packets (arriving from|sent to) the port (without a tag/with that tag) will be (tagged|untagged). Can someone who fully understands this please select A or B for each of the 4 parenthesized items (in as many permutations as make sense). I guess that in one of the modes, untagged packets going in one direction or the other will be tagged, and vice versa, I just don't know which direction does which, and for which mode, and don't want to guess. (I'm asking this because I want to implement identical functionality for standard Linux host bridges - I want to make sure there are no surprises for people switching between OVS and Linux host bridge implementations). To report this email as SPAM, please forward it to spam(a)websense.com