extend vlan across a point-to-point layer 3 network

I have a voice vlan on one of my building and I'd like to extend it to the other building. There is a fiber connection between the 2 buildings and It is a layer 3 connection.

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leblancAccountingAsked:
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naderzCommented:
I would:

1.  put the Vlan50 in the building on the left in 192.168.50.0/24 network.
2. Trunk Vlan2 and Vlan50 between switch0 and sw2
3. create interface vlan50 (192.168.50.1/24) on sw2.
4. configure ip helper address on sw2 for Interface Vlan50 pointing to Server-PT IP address
5. Make sure all routing between 192.168.x.x and 10.20.x.x is configured correctly. In this case static routes would suffice.
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leblancAccountingAuthor Commented:
vlan50 192.168.50.1 is already on sw1. How can the same subnet be defined in 2 different broadcast domains. the connection between sw1 & sw2 is a layer 3 routed link.
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StolsieCommented:
are you actually working with a router or a layer 3 switch?
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leblancAccountingAuthor Commented:
Yes Catalyst 3560.
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StolsieCommented:
Cool a layer 3 switch, give me a few minutes to program one on packet tracer.
I do exactly what you want but using HP 8212. Not sure on the commands with Cisco it’s been about 5 year’s lol
You need the traffic on the same Vlan preferably with QOS and obviously tagged or you lose the QOS between links.
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StolsieCommented:
Wow I forgot how over complicated Cisco like to do things.
Anywho correct me where I’m wrong.
Sw1: Fa0/1-mode access vlan (unknown ip 10.10.10.1/30)
Sw2: Fa0/1-mode access vlan (unknown ip 10.10.10.2/30)
Sw1: Fa0/2 vlan 20 & 50 Trunked mode allow/native? /encapsulation dot1.q
Sw2: Fa0/2 vlan 2 trunk mode allow 2/ native? /encapsulation dot1.q
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I’m hoping you will say I have it wrong
And the Fa0/1 ports are set to trunk mode/ encapsulation/ native vlan (unknown)
Cause then you can just add vlan 50 along with the QoS and boom away you go.
Why do you have routing enabled on both sites, your servers are at site A so your clients at site B will need to come to site A anyway why put a router there?
Unless you have left loads out for example sake
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naderzCommented:
eblanc: If you read my steps, I don't have the same subnet in two different locations. Your VLAN 50 in on 192.168.50.0/24 on the left. You will then route between the two locations. Follow the steps, and it will work.
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leblancAccountingAuthor Commented:
naderz,

You're right. So you assigned another subnet for the phone in network 192.168.50.0/24. I think the problem here is now I have two dhcp scopes on the server. How will phones interact with each other? Will the routing in the VoIP system?
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naderzCommented:
Correct, you will need a DHCP scope for each subnet. And, since VoIP traffic is IP, the routers and L3 switches will route the traffic just fine. Just like any other IP traffic. Think of the IP phones as just another IP device that needs to get to another subnet. Traffic between the VoIP phones will route just like the other IP traffic.

You have two subnets (Vlan20 & 50) on the right hand side. And, now you need two (Vlan20 and 50) on the left hand side. Note Item4 in my steps: configure IP Helper address on sw2 so that the IP phones go to the Server-PT for DHCP.

And, remember that Vlan is a L2 concept and can exist in any building or location with any IP address subnet you want.

Are you using Cisco CallManager (CUCM)?

Let me know if any clarification is needed.
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leblancAccountingAuthor Commented:
No we run Mitel. Another vendor is taking care of that part.
I understand your explanation and this is not really an extended vlan because we created another subnet. I heard that is a way to extend a vlan. In other words, keeping the IP addresses of the same subnet in another domain broadcast, something like lt2pv3.

Thanks
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naderzCommented:
Well, for what you have I still recommend the steps I had listed above. l2tpv3 is not really recommended as it will introduce complexity to your design and will tax the 3560 performance. And, you are not really gaining anything. I haven't even checked to see whether 3560 supports it. My suggestion would be to use distinct Voice Vlans for each subnet and route them. easy peasy :)
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StolsieCommented:
Don’t know why you wouldn't pass your VoIP traffic from your layer 3 switch to the other network as if it was switch to switch? That is the main perk of going layer 3 switch and not router
in the other hand if you are just creating another VoIP IP range on another network so you have two scopes on the Mitel unit i can give you some guidance on the providing the configuration is the same or not too far off of the 3300 kit.
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leblancAccountingAuthor Commented:
I see. Thanks for the explanation. You mentioned providing some guidance on the configuration. Is it for the Mitel unit or something else? If yes please do. You seem to know what you are doing. Thanks again
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StolsieCommented:
Yeah i meant Mitel :)
What have you decided to do?
Treat your VoIP network as a flat network between two sites or create a new VoIP IP scope at site 2?
If you have decided to create a new scope what range and vlan ID?
Also do you know if you’re current DHCP scope on Mitel is set globally or network specific?
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leblancAccountingAuthor Commented:
There will be 2 scopes for the VoIP on that dhcp server. 1 is for the phone on the right (vlan50 192.168.100.0/24) and the other one is for the other one on the left (vlan50 10.20.50.0/24). The link between sw2 and sw1 is a layer 3 link. "DHCP scope on Mitel is set globally or network specific" I am not sure but what is the difference.
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naderzCommented:
You need network specific DHCP scopes. One for each network.

You need to route the traffic between the two sites. Just follow the steps I had above.

Do you need help with configuring the Mitel?
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leblancAccountingAuthor Commented:
Somebody else will do the Mitel part. Thanks
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naderzCommented:
Then these steps will work:
1.  put the Vlan50 in the building on the left in 192.168.50.0/24 network.
2. Trunk Vlan2 and Vlan50 between switch0 and sw2
3. create interface vlan50 (192.168.50.1/24) on sw2.
4. configure ip helper address on sw2 for Interface Vlan50 pointing to Server-PT IP address
5. Make sure all routing between 192.168.x.x and 10.20.x.x is configured correctly. In this case static routes would suffice.
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