I have been struggling with the evil VTP also. ;-) I have a few questions.
Is VTP required? Cisco instructions regarding VLANs usually start with
having you configure VTP, but do you need VTP? (assume a small network with
few VLANs)
How does VTP interact with trunks, if at all? I can configure a trunk to
carry traffic for a subset of the VLANs that VTP advertises, can't I? (not
sure why I would want to, but I'm just confirming your point that VTP is
misnamed, e.g. it is not a trunking protocol)
Now, for my troubleshooting problem. I have two switches connected
back-to-back, with two VLANs that span the switches. I had my switches in
VTP transparent mode and manually configured the VLANs, VLAN 10 and 50,
Engineering and Accounting on both of them. Then I put them both in server
mode and gave them both the VTP domain name "Lab."
After hours of troubleshooting reachability problems between hosts
connected to the switches, and using a sniffer on a monitor port that was
monitoring the trunk, I was beginning to suspect problems with flooding of
unknown unicasts. I finally ran into the documentation about VTP pruning.
Despite the fact that this feature is not enabled, the only thing that
fixed my reachability problems was to configure the following on each side
of the trunk:
vtp trunk pruning-disable 10 50
The implication is that my switches thought they were not in the same
domain and so were pruning. Evil things. I checked the VTP domain name over
and over again. They are both in "Lab."
SwitchC#show vtp
VTP version: 1
Configuration revision: 2
Maximum VLANs supported locally: 1005
Number of existing VLANs: 7
VTP domain name : Lab
VTP password :
VTP operating mode : Server
VTP pruning mode : Disabled
VTP traps generation : Enabled
Configuration last modified by: 172.16.10.3 at 00-00-0000 00:00:00
SwitchC#
SwitchA>en
SwitchA#show vtp
VTP version: 1
Configuration revision: 2
Maximum VLANs supported locally: 1005
Number of existing VLANs: 7
VTP domain name : Lab
VTP password :
VTP operating mode : Server
VTP pruning mode : Disabled
VTP traps generation : Enabled
Configuration last modified by: 172.16.10.3 at 00-00-0000 00:00:00
SwitchA#
I think I ran into a bug. Notice that pruning is supposedly disabled. I'll
keep troubleshooting and try to reproduce the problem. Any advice, though?
Should I have started with the swithces in server mode perhaps? That might
have helped. Or one in client, although the documentation claims that
Catalyst 1900s can't be configured for client, (which seems to be wrong,
though. I am able to configure client mode.)
Thanks. Sorry for the length of this message! :-]
Priscilla
At 04:03 AM 7/13/01, Karen E Young wrote:
>CM,
>
>The name of this protocol is misleading (VTP = VLAN Trunking Protocol) since
>it doesn't really have anything to do with trunking. VTP is merely a way to
>update the VLANs that a switch recognizes as valid on multiple switches by
>updating a single "server". All of the rest of the switches in the VTP
>domain get a copy of the list of valid VLANs from the server. What this
>means is that when you add a new VLAN to the network you only have to define
>it on the server. All of the rest of the switches get it automatically. If
>you don't want to use VTP, then each VLAN needs to be configured manually on
>each switch. This can easily lead to problems if you mistype.
>
>A "VTP domain" is a bunch of switches on a network that will have the same
>VLANs configured on them. If you have more than one group of switches and
>each group has a different set of VLANs that it has to recognize, then you
>use a seperate domain name for the second group. You also need to keep in
>mind that VTP won't cross WAN links so portions of your network that span a
>WAN link will automatically have different VTP domains on each end of the
>link even if the domain name is configured identically on each end.
>
>HTH,
> Karen
>
>*********** REPLY SEPARATOR ***********
>
>On 7/10/2001 at 12:48 PM getme wrote:
>
> >What configuration is pushed out to other domain members using vtp ?
> >As far as i know trunks carry the vlan information, in servers u can
> >make/del/modify vlans and in clients u cannot. Is that all??
> >
> >
> >On Tuesday, July 10, 2001 at 01:24:13 PM, Charles Manafa wrote:
> >
> >> VLANs are created by switches operating in Server mode, and VTP is the
> >means
> >> by which the configuration is pushed out to other domain members.
Switches
> >> operating in Client mode can not create/delete/modify VLANs, but can use
> >the
> >> VLANs already created.
> >>
> >> CM
> >>
> >> > -----Original Message-----
> >> > From: getme [mailto:[EMAIL PROTECTED]]
> >> > Sent: 10 July 2001 13:04
> >> > To: [EMAIL PROTECTED]
> >> > Subject: urgent question related to vtp [7:11687]
> >> >
> >> >
> >> > Hi,
> >> > I am kinda confused. Wot i understood from the doucumentation
> >> > is that in vtp
> >> > domains, we can add vlans from server on clients. Can this be
> >> > done? and if
> >> > yes how its done?
> >> > i am using 2900xl
> >> >
> >> > Thanks in advance
> >> >
> >> > --
> >> > Do you VisualMail?
> >> >
> >> > Grab a copy of the best WebMailer right now!
> >> >
> >> > http://www.mintersoft.com/visualmail
> >--
> >Do you VisualMail?
> >
> >Grab a copy of the best WebMailer right now!
> >
> >http://www.mintersoft.com/visualmail
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
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