On Fri, Jan 23, 2015 at 5:27 PM, Boris Epstein <borepstein at gmail.com> wrote: > Hello all, > > I have a machine running Centos 6.6 connected to a port on a Cisco Catalyst > 3750 series switch. That port is part of VLAN 48. I have VLAN 48 on the > CentOS machine too. > > The IP network on VLAN 48 is 192.168.48.0/255.255.255.0. The address on the > CentOS side is 192.168.48.101, the address on the Linux end ought to be > 192.168.48.100. > > When I only bring up eth0.48 VLAN device with the IP=192.168.48.100 I have > no connectivity. If I bring it up along with eth0 with another VLAN 48 > address assigned to it (for instance, 192.168.48.99) I do have connectivity. > > Also, strangely enough, sometimes to get things going I have to disconnect > the Linux host from the switch - physically detach the wire and reconnect > it again. > > Be that as it may when I just bring up the VLAN by itself I have thus far > been unable to get anywhere. > > Has anybody seen a situation like this? Does anybody have an explaination > for it? I think you always have to bring up the underlying eth device to activate a related eth.nn vlan. The base device would not normally have an IPADDR, though, unless it is for an untagged vlan 0. Assuming the connected switch port is configured as a trunk, you shouldn't see vlan 48 addresses on the base (untagged) device. -- Les Mikesell lesmikesell at gmail.com