"What do you get if you issue show vtp status?"
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Browse All TopicsHello EE,
Many of you have been following my posts pertaining to a major upgrade to Metro Ethernet. Last Thursday evening, we moved forward with 4 of our sites. Everything went very smoothly until we got to SITE D. This is when we ran across what we believe to be a VLAN tag related issue. Here is the rundown of what we did.
SITE A:
We installed a Cisco 2821 router in our main data center. This new router is touching the metro cloud and we assigned the metro port the address 10.10.10.1. Another port on this device is connected back to our existing network infrastructure. Remote sites are to be migrated from the existing network to the fiber one at a time. All routes are good and tested. The Router is up and routing traffic right now.
SITE B:
We installed a Cisco 2811 router in the data center at our Police Station. This router is touching the metro cloud and has an address of 10.10.10.2. The other port on this device is connected to the switches that contain all the users and server on the 192.168.111.0 subnet. Addresses are statically assigned. All routes are good and tested. The Router is up and routing traffic right now.
SITE C:
We installed a Cisco 3560 switch on this site. L2 routing capabilities are enabled. The switch is touching the metro cloud and has an address of 10.10.10.3. There is a VLAN20 interface with the address 192.168.109.1. All the users connected to this switch are assigned to VLAN20, and address are assigned through DHCP. All routes are good and tested.
SITE D:
We installed a Cisco 3560 switch on this site. The switch and the configuration is identical to the switch at SITE C, with the exception of the hostname and the IP addresses. The switch is touching the metro cloud and has an address of 10.10.10.4.
Here is where the problem begins. When I plugged it in and did a few housekeeping procedures (i.e. removed erroneous routes) interface VLAN20 would not come up no matter what I tried. From the switch console i could ping everything on the network, but nobody else could see past the metro port at site D. Here is some of the the step I took to resolve the issue.
blew away the vlan20 interface and started over - NO CHANGE
created a new vlan interface (VLAN220) and assigned the network ip address to that - NO CHANGE
reloaded the config from our TFTP server - NO CHANGE
reloaded the config from the switch at SITE C and changed hostname, ip's, etc - NO CHANGE
replaced with a whole different switch - NO CHANGE
Nothing I did would bring that vlan interface up. Finally our desperation and pure exhaustion, at 11:45, I decided to assigned the network ip to the vlan1 interface and what do you know, all the ports on the switch that were lit up amber all turned green and all the pc's at SITE D started grabbing DHCP. We desided to leave it alone for now and research what went wrong. so my question is this.
Why would the VLAN20 interface not come online?
Did it have something to do with an active VLAN20 running at site C?
An earlier post here suggests that the switches are oblivious to the VLANS on other switches in a setup like this.
What more should I be looking at?
What are the dangers of running traffic on VLAN1?
The hard part is done. Now we need to work out the kinks before we move the other 7 sites over. I have attached a diagram and the configs I want to use for reference.
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try issuing:
set vlan 20 state active
Now, I have to think about it, but since the 3560's are L2/L3 devices if VLAN20 on both switches are not part of the same VLAN, then you should either have each of them have different VLAN's, or have them be part of two different VTP Domains.
I will need to look at your configs some more as something does not seem right about this.
What is the bandwidth on the Metro networks?
You do realize that means that all broadcast traffic will be sent across the metro network to all sites?
I would suggest that you keep each site as its own VLAN (meaning each site will be its own IP subnet) so that you don't eat up the WAN traffic with broadcasts.
Unless there is some reason you want to do that. It will be a 4-5 hours before I can respond again.
I agree that each site needs to be on its own subnet. However, they also need to be on different VLAN's.
Even with each site having their own VLAN's I would also suggest that each site be part of its own VTP domain. This way VLAN information is not exchanged between the switches at different sites.
The problem you are most likely having is that the 3560 are L2 and L3 devices and so they are exchanging L2 VTP information. Where as it looks like the other sites have L3 only devices, so no VTP information is exchanged.
Ok, lets say for the sake of argument that we want to put everything on the same VTP domain? Am I correct in assuming that we need to have only one VTP server? How would we go about implemeting this. Does our router at SITE A house the VLAN database?
Our ultimate goal is to secure the sensitve areas without locking us (meaning IT) out of anything. here is a diagram that best illustrates our end goal.
If you wanted to have a single VTP domain, then yes, you would want to have only one VTP server.
However, you stated you wanted to route between sites across the metro network. So VLAN20 at "SITE1" will NOT be the same VLAN20 at "SITE2". This could be very confusing if you were to do this. The connections to the metro network are not trunks, but are just "normal" single VLAN connections, except possibility in the sites where you have L3 switches.
From your diagram it looks like you wannt have VLAN20 at 10 or so sites. However this will not be a single VLAN20, but 10 independent VLAN20's. That would be very confusing, since normally VLAN's are a single broadcast domain and traffic within a VLAN is switched, not routed.
You should also have problems with your management VLAN10. Since all of the switches/routers management IP address are within the same subnet, they will assume they can communicate directly with each other, no routing involved. However, since the connections to the metro network are access mode ports, there is no switching only routing. So you will have problems getting to the management IP addresses.
More confusion is certainly not needed. Assuming we put each site on separate VLANS can you offer up a suggested solution that meets some the following criteria.
All sites able to talk to data center
All sites accessible to IT
Secure segregation of specific site (still keeping management access)
That would make 13 VLANS,
1 - Management (IT Workstations)
1 - Servers or Data Center (or should these be kept on the native?)
3 - Secure (only accessible to the user assigned to that VLAN, Servers, and Management)
8 - Regular users (workstations and printers)
I have a tenancy to over complicate things, so if there is an easier way to do what we want done please help me out.
Speaking of over complicating, I have attached new diagram.
I have not forgotten about this. I'm just thinking things through to make sure that I'm not overlooking things. One suggestion is that you do NOT put your servers on the native VLAN. Nothing should be put on native VLAN if at all possible.
Part of what makes this a bit complicated is that when typically when you have a WAN each site is considered a totally separate site and you can use the same VLAN number at each site. VLAN information is not transmitted at all when using only routers.
However, when using Metro Ethernet its not really a WAN, it is more like a LAN. So instead of considering each site as a standalone network, you have to treat it as if it were one building and segmenting the whole building into smaller LAN's and that the "back bone" connection (the Metro Ethernet) is 'slow' and has high latency so you don't want to do L2 functions across the "back bone".
If you look at Cisco's 3 layer network architecture you will notice that they have access layer, distribution layer, and the core layer. At the core they strongly suggest that you route (L3) between cores and to/from the distribution layer. At the distribution layer you switch between to any distribution layers that are directly connected to each other and switch between the access layer.
In your setup you really don't have a core layer. You are interconnecting the distribution layer (the switches/routers at each site) with each other. So you want to route there to reduce traffic that is crossing over the Metro network. You also are mixing switches and routers at the distribution layer which gives you a mixture of capabilities (L2/L3 switching vs. L3 routing only) which means you need to account for VTP on the devices that support it.
What would be the outcome if I turned VTP off all together. I understand that it I do shut down VTP, VLAN20 at SITE C will never know that SITE also has a VLAN20. I'm ok with that as long as everyone can talk to the servers and to the internet. For the sake of argument, let say I turn off VTP on all devises. Will this fix the current problem?
Resolved on my own by doing the following
1. Set VTP mode to Transparent at each site
2. Assigned a Unique VTP Domain Name to each site
3. Assigned each site to their own VLAN and Subnet
Put SITE E in server today with no problems. will be making the change to the exiting site after hours.
Thanks for the help.
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by: giltjrPosted on 2008-11-10 at 10:38:54ID: 22924176
What do you get if you issue show vtp status?