[PLUG] OT VLAN Setup between 2 Cisco switches

[Chuck Hast]

OK, on the two SG200-50p units I have SPF port 50 on VLAN 2
(Actually 20 ) and ticked as [trunk] I have screen captures of the
two ends of the link and both fibre ends are marked [trunk]  I
had figured that from what I had read, the document above
made it very clear. I do not see ANY VLAN appearing on the
far end, even though SW 2 port 50 is in VLAN 2 and marked
as [trunk]. The interesting thing is if I unplug the other SPF
transceiver then the link will come up and I can reach the
equipment on VLAN 2 and also I get a DHCP assignment.
As soon as I plug the other SPF into port 49, the link to
VLAN 2 goes away, the SPF in port 49 connects to VLAN
1, and the connection is lost to VLAN 2 via SPF in port
50.

Wish I could attach the two screen captures here, so you
can see what I have, you will probably see something that
I am missing.



On Sun, Aug 2, 2020 at 12:42 PM Mike C. <mconnors1 at gmail.com> wrote:

> >
> > The two switches talk just fine between the two devices on
> > VLAN 1.
> >
>
> Yes, because the default / admin VLAN 1 is automagicaly extended across
> switches for obvious reasons.
>
>
> > But VLAN 2 will not talk.
>
>
> VLANs are broadcast domains, and with the exception of the default/admin
> VLAN 1, unless you extend the vlan broadcast domain intentionally, vlan
> traffic stays local to the switch.
>
>
>
> > The interesting thing is that if Iunplug the SFP transceiver in port 49
> > (associated with VLAN 1) then VLAN 2 will start to talk to the other
> switch
> > over the SFP device in port 50.
> >
>
> This is the Spanning Tree Protocol unlblockiing and finding a new route
> after a link failure.
>
>
> > I am assuming configuration somewhere but not sure where.
> >
>
> Correct assumption. You need to configure a vlan trunk for VLAN 2 to
> traverse the fiber links between the 2 switches,
>
>
> https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/vlan/configuration_guide/b_vlan_3se_3850_cg/b_vlan_3se_3850_cg_chapter_0110.pdf
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-- 

Chuck Hast  -- KP4DJT --
I can do all things through Christ which strengtheneth me.
Ph 4:13 KJV
Todo lo puedo en Cristo que me fortalece.
Fil 4:13 RVR1960