[CentOS] VLAN issue

Fri Jan 23 23:45:16 UTC 2015
Les Mikesell <lesmikesell at gmail.com>

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 The address on the
> CentOS side is, the address on the Linux end ought to be
> When I only bring up eth0.48 VLAN device with the IP= I have
> no connectivity. If I bring it up along with eth0 with another VLAN 48
> address assigned to it (for instance, 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