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New Member

VLAN routing across 1921's

I asked this in the LAN forum but I don't think people understood what I was asking.  I want to know if I can route VLAN's across my T1 point to point connection using 1921 routers.  I currently have AdTran 3205's and although I found info on the internet saying you can make them do this I could not after many hours of trying.  I also found this article: http://www.cisco.com/en/US/tech/tk389/tk815/technologies_tech_note09186a0080094663.shtml  that also seems to say I can do what I want but I just want to verify.

We have two main locations currently connected by a point to point T1 (1.54Mbps) through the AdTran 3205's.  We are running out of IP addresses as we just have a single subnet on each end.  I want to move to a VLAN setup for a couple reasons including security and QoS for our voice system.  Each location has it's own dedicated internet and proxy server.  Here is my planned layout:

          ISP 1                                      ISP 2
            |                                          |
            |                                          |
            |                                          | 
            |                 10.0.0.0/30              |
    Layer-3 Switch 1 -- 1921-1 ---------- 1921-2 -- Layer-3 Switch 2
    |      |       | .1                          .2 |      |       |
    |   VLAN 20    |                                |   VLAN 20    |
    | 10.1.20.0/24 |                                | 10.2.20.0/24 |
    |              |                                |              |
  VLAN 10        VLAN 30                          VLAN 10        VLAN 30
10.1.10.0/24   10.1.30.0/24                    10.2.10.0/24    10.2.30.0/24
 
       Building #1                                     Building #2

Can I do this with the 1921s?  Is there a better design for what I want to accomplish (seperate our users, servers, and phones onto seperate VLAN's)?

-Allan

Everyone's tags (3)
1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Bronze

VLAN routing across 1921's

I don't see any issues with your design.

Since your layer3 switch will be hosting the Vlans, the 1900 router will need to know about those subnets either via dynamic routing protocol or static routing.

The same can be said by learning the remote subnets via the T1.

What routing protocol do you have in mind?

For this setup, EIGRP will be easier but OSPF is more robust if you are planning to increase your network.

6 REPLIES
Hall of Fame Super Bronze

VLAN routing across 1921's

I don't see any issues with your design.

Since your layer3 switch will be hosting the Vlans, the 1900 router will need to know about those subnets either via dynamic routing protocol or static routing.

The same can be said by learning the remote subnets via the T1.

What routing protocol do you have in mind?

For this setup, EIGRP will be easier but OSPF is more robust if you are planning to increase your network.

New Member

VLAN routing across 1921's

Once this is in place I shouldn't have to make a network structure change for 5+ years.  Our current DHCP scope is .65 - .229 and we are at 95% full...with the new VLAN's we can use .2 - .254 which should last us a couple years plus I could use something other then a /24 subnet on the VLAN without much trouble.

So once put in place I wouldn't be changing anything until I replace switches.  With that said what would be easiest to use?  EIGRP?  Couldn't I just manually assign the routes or would that not make sense?

Hall of Fame Super Bronze

VLAN routing across 1921's

One caveat on EIGRP, it is Cisco proprietary thus if your layer3 switches aren't Cisco, you need to use OSPF or RIP.

Per your diagram, it's fairly easy to do EIGRP.

On each Layer3 switch, just do:

router eigrp 1

no auto-summary

network 10.2.0.0 0.0.255.255

router eigrp 1

no auto-summary

network 10.1.0.0 0.0.255.255

On the routers:

router eigrp 1

no auto-summary

network 10.2.0.0 0.0.255.255

network 10.0.0.0 0.0.0.3

router eigrp 1

no auto-summary

network 10.1.0.0 0.0.255.255

network 10.0.0.0 0.0.0.3

New Member

VLAN routing across 1921's

My switches are Dell 6248's on both ends then 5448s and 3448s throughout the offices so it looks like I would have to use OSPF.

Looks like I'll be ordering some 1921's today.  Thank-you very much for your replies Edison....hopefully I can figure out how to get these setup.

Hall of Fame Super Bronze

VLAN routing across 1921's

OSPF with the Cisco routers won't be much different than EIGRP, for intance:

On the routers:

router ospf 1

network 10.2.0.0 0.0.255.255 area 0

network 10.0.0.0 0.0.0.3 area 0

router ospf 1

network 10.1.0.0 0.0.255.255 area 0

network 10.0.0.0 0.0.0.3 area 0

New Member

VLAN routing across 1921's

The point to point is a relatively slow 1.5Mbps T1.  Would static routing make sense?  We dont see growing much beyond what we have planned for this upgrade.

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