[c-nsp] Point to Point T1's and vlan nightmares

Fri Jul 27 21:07:50 EDT 2012

Yeah, don't get too comfortable with vtp...my me3600x doesn't even run it...

One thing I like about vtp is in the huge L2 network that I run for an ISP,
when I want to create a vlan, it does it everywhere.

One thing I don't like about vtp is that when it creates vlan's everywhere,
I have pvst spanning tree instances in every single switch, even where I
don't really want that vlan to exist.

3600#sh ver | in ME3
Cisco IOS Software, ME360x Software (ME360x-UNIVERSALK9-M), Version
15.2(2)S, RELEASE SOFTWARE (fc1)
BOOTLDR: ME360x Boot Loader (ME360X-HBOOT-M), Version 12.2
[sourdutt-loader_release_ledfix 100]

3600#sh vtp ?
% Unrecognized command

Aaron

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Oliver Garraux
Sent: Friday, July 27, 2012 4:38 PM
To: Blake Pfankuch
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Point to Point T1's and vlan nightmares

Preventing duplicate VLAN numbers sounds like it could be better solved
through process changes rather than technical changes.  Maybe a wiki or a
spreadsheet, or a single person that's in charge of assigning new VLAN's.

(Not trying to be argumentative, just thinking that VTP may not be the best
way to solve the issue you're concerned about).

-------------------------------------

Oliver Garraux
Check out my blog:  www.GetSimpliciti.com/blog Follow me on Twitter:
twitter.com/olivergarraux

On Fri, Jul 27, 2012 at 5:27 PM, Blake Pfankuch <blake at pfankuch.me> wrote:
> We are utilizing eigrp internally.
>
> Using vtp v3 is for pruning primarily.  This will be a large multi site
voice deployment as well, right now im sitting at 213 vlans across all
sites, and trying to make it as easy as possible for their staff to manage
and not accidentially create a new vlan in 2 different sites like vlan 450
and then start utilizing them then have to change it once everything is on
the fiber mesh.  Once the fiber is in place, there will be a few extensions
of single vlans from 1 site to another due to the way some very poorly
designed network devices work but that's another rant.  So we will have
trunks between sites.
>
> -----Original Message-----
> From: JP Senior [mailto:SeniorJ at bennettjones.com]
> Sent: Friday, July 27, 2012 3:21 PM
> To: Blake Pfankuch; cisco-nsp at puck.nether.net
> Subject: RE: Point to Point T1's and vlan nightmares
>
> It sounds like you should be focusing more on a layer 3 solution than a
layer 2 solution - run an IGP between your 3560s or 3750s. Even if you did
have proper fiber connectivity between locations, you should be isolating
VTP (if _absolutely_ required) to single sites.  You should also reconsider
running VTP in the first place, it's a terrible protocol which can destroy
entire networks in a single packet.
>
> Do you have any specific reason to run layer 2 between sites in a private
network?  It is extremely rare that this is ever a good idea and management
of vlans using a single vtp source isn't one of them.
>
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net 
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Blake Pfankuch
> Sent: 27 July 2012 1:51 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Point to Point T1's and vlan nightmares
>
> OK, First off if this is a bad idea just say so and move on, I don't want
to start a giant flame war :)  Also forgive me for this being a little long
winded.
>
> Working with a customer of mine who is actually doing a very nice
switching replacement.  All switches are Cisco 3750X or Cisco 3560X and will
be supporting multiple vlans.  Currently they have about 8 locations which
are point to point T1 connected, and about 6 more that are connected on a
private fiber ring.  Eventually they will all be on a private fiber ring,
and this will all be a moot point, but I'm looking for the "keep it pretty
until its complete" solution right now.
>
> Because of the quantity of vlans being added, and the fact that it will be
customer managed, I would like to force a single VTP domain across all
locations, and have a single primary server running under vtp3.  This will
prevent they user from adding conflicting vlans at different sites and
having to pay me to come fix it for a week before they can turn up fiber.
My questions is as follows.
>
> Within Location A, I have a Cisco 3750X stack connected to a cisco 2921
router.  This router has 3 dual port T1 wic's.  Example Location B site has
a Cisco 3750X stack connected to a Cisco 2901 router with a single T1 wic.
>
> On Location A switch I create the following
>
> Interface vlan 801
> Ip address 172.16.255.1 255.255.255.252
>
> Int gi 1/0/1
> Switchport trunk encapsulation dot1q
> Switchport mode trunk
> Switchport trunk allowed vlan 801
> Switchport trunk native vlan 801
>
> Then connect gi 1/0/1 to gi0/0 on the Location A2921 router and configure
on the router as follows.
>
> Int gi 0/0
> No ip address
>
> Int gi 0/0.801
> No ip route cache
> Bridge-group 1
>
> Int ser 0/0/0
> No ip address
> Bridge-group 1
>
> Int bvi1
> No ip address
>
> Bridge 1 protocol ieee
>
> Then connect that Location A 2921 ser 0/0/0 to Location B 2901 ser 
> 0/0/0 and apply this configuration to the 2901
>
> Int gi 0/0
> No ip address
>
> Int gi 0/0.801
> No ip route cache
> Bridge group 1
>
> Int ser 0/0/0
> No ip address
> Bridge-group 1
>
> Int bvi 1
> No ip address
>
> Bridge 1 protocol ieee
>
>
> From Gi 0/0 on this router connect to gi 1/0/1 on the cisco 3750X stack at
location B with the following configuration.
>
> Interface vlan 801
> Ip address 172.16.255.2 255.255.255.252
>
> Int gi 1/0/1
> Switchport trunk encapsulation dot1q
> Switchport mode trunk
> Switchport trunk allowed vlan 801
> Switchport trunk native vlan 801
>
>
> This "should" in my mind leave the point to point t1 links working
correctly for now, allow VTP to continue functioning and pass information
across the bridged point to point t1 until these links are replaced with the
final fiber links between sites (eta 6-10months), and prevent the user from
mangling the nice pretty vlan configuration before it's a single mesh
network.  Also allowing me to create multiple bridge to vlan subinterface
networks to handle the multiple physical point to point circuits flowing on
this single router.
>
> Thoughts?
>
> Thanks in advance!
>
> Blake
>
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