CentOS - Jan 2015 - VLAN issue

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
>

On Fri, Jan 23, 2015 at 5:48 PM, Boris Epstein <borepstein at gmail.com>
wrote:
> 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.
Doesn't make sense to me - I think I've done it both ways
(with/without a vlan 0 address).  I didn't think it took anything
special except the VLAN=yes in the file and the .number in the DEVICE(and file)
name.

-- 
  Les Mikesell
    lesmikesell at gmail.com

On Fri, Jan 23, 2015 at 7:02 PM, Les Mikesell <lesmikesell at gmail.com>
wrote:
> On Fri, Jan 23, 2015 at 5:48 PM, Boris Epstein <borepstein at
gmail.com>
> wrote:
> > 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.
>
> Doesn't make sense to me - I think I've done it both ways
> (with/without a vlan 0 address).  I didn't think it took anything
> special except the VLAN=yes in the file and the .number in the DEVICE>
(and file) name.
>
> --
>   Les Mikesell
>     lesmikesell at gmail.com
>

This makes two of us. I've done everything as you have described and it
simply does not work.

Boris.


>
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