Less, You are 100% right. Of course I brought up my eth0 - but, like you said, with no IP. Meanwhile, I brought up eth0.48 with 192.168.48.100. However, until I would bring up eth0 with an IP address (any in the network) I would have no connection. Why? That's what I fail to understand. Boris. On Fri, Jan 23, 2015 at 6:45 PM, Les Mikesell <lesmikesell at gmail.com> wrote: > 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 > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >