| Message ID | 20081006202554.11354b09@speedy |
|---|---|
| State | Deferred, archived |
| Delegated to: | David Miller |
| Headers | show |
Stephen Hemminger wrote: > Propogate MTU changes of underlying device to all VLAN's and > send vlan MTU change out to userspace. > > see: https://bugzilla.vyatta.com/show_bug.cgi?id=3742 > > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> > > > --- a/net/8021q/vlan.c 2008-10-06 17:03:58.000000000 +0200 > +++ b/net/8021q/vlan.c 2008-10-06 19:55:43.000000000 +0200 > @@ -477,6 +477,17 @@ static int vlan_device_event(struct noti > > break; > > + case NETDEV_CHANGEMTU: > + /* Propogate MTU of underlying device */ > + for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) { > + vlandev = vlan_group_get_device(grp, i); > + if (!vlandev) > + continue; > + > + dev_set_mtu(vlandev, dev->mtu); > + } > + break; > + > case NETDEV_DOWN: > /* Put all VLANs for this dev in the down state too. > */ for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) { It has been a while since I worked with vlan tags, but I was just curious. Shouldn't the vlan mtu be set to dev->mtu - VLAN_HLEN? It seems like if the vlan and the device have the same mtu then you will always have issues since adding the vlan tag will increase the overall size and push the packet outside mtu size. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2008-10-06 at 11:45 -0700, Duyck, Alexander H wrote: > Stephen Hemminger wrote: > > Propogate MTU changes of underlying device to all VLAN's and > > send vlan MTU change out to userspace. > > > > see: https://bugzilla.vyatta.com/show_bug.cgi?id=3742 > > > > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> > > > > > > --- a/net/8021q/vlan.c 2008-10-06 17:03:58.000000000 +0200 > > +++ b/net/8021q/vlan.c 2008-10-06 19:55:43.000000000 +0200 > > @@ -477,6 +477,17 @@ static int vlan_device_event(struct noti > > > > break; > > > > + case NETDEV_CHANGEMTU: > > + /* Propogate MTU of underlying device */ > > + for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) { > > + vlandev = vlan_group_get_device(grp, i); > > + if (!vlandev) > > + continue; > > + > > + dev_set_mtu(vlandev, dev->mtu); > > + } > > + break; > > + > > case NETDEV_DOWN: > > /* Put all VLANs for this dev in the down state too. > > */ for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) { > > It has been a while since I worked with vlan tags, but I was just > curious. Shouldn't the vlan mtu be set to dev->mtu - VLAN_HLEN? > > It seems like if the vlan and the device have the same mtu then > you will always have issues since adding the vlan tag will > increase the overall size and push the packet outside mtu size. An MTU of 1500 is commonly taken to correspond to the IEEE 802.3 maximum frame size of 1518 bytes which allows for a VLAN tag, and more generally maximum frame size is set to MTU + 18. However, not all drivers agree with this interpretation. Ben.
Stephen Hemminger wrote: > Propogate MTU changes of underlying device to all VLAN's and > send vlan MTU change out to userspace. > > see: https://bugzilla.vyatta.com/show_bug.cgi?id=3742 This really doesn't answer any of the questions related to this change, mainly whether this kind of behaviour shouldn't be user controllable. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/net/8021q/vlan.c 2008-10-06 17:03:58.000000000 +0200 +++ b/net/8021q/vlan.c 2008-10-06 19:55:43.000000000 +0200 @@ -477,6 +477,17 @@ static int vlan_device_event(struct noti break; + case NETDEV_CHANGEMTU: + /* Propogate MTU of underlying device */ + for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) { + vlandev = vlan_group_get_device(grp, i); + if (!vlandev) + continue; + + dev_set_mtu(vlandev, dev->mtu); + } + break; + case NETDEV_DOWN: /* Put all VLANs for this dev in the down state too. */ for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) {
Propogate MTU changes of underlying device to all VLAN's and send vlan MTU change out to userspace. see: https://bugzilla.vyatta.com/show_bug.cgi?id=3742 Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html