layer 3 setup help

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Jun 1st, 2009
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I'm looking to setup layer 3 routing with ospf between 4 locations. Right now I would just like to get it up and running between 2 of the locations. I'd also like to have each location vlan'ed. I'd like to have excess traffic between the location minimized. The main location (Location 0 in the configs) is going to have a cisco 3750 stack of 2 switches. vlan 1 was already existing on the cisco stack when I inherited this network. I'd like to leave that in place for legacy equipment. I'd also like it if all the other vlans that get setup can still access equipment on that vlan. The satellite locations will be using HP 3400cl switches. The locations will be connected via 100mb fiber connections.

I've attached the parts of the hp/cisco switch configs that i'm concerned about. I'm fairly certain I haven't done this correctly. If anyone could point out my mistakes that would be great.



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Giuseppe Larosa Mon, 06/01/2009 - 11:04
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Hello William,

key point:

OSPF adjacencies can be built only on primary ip addresses.

the area-id , area type must match

hello time and dead interval must match.

OSPF router-ids must be different

in your case

/30 move in steps of 4 addresses

the l2 vlan tags must match if you are using an 802.1Q trunk.

if all this is correct it should work.


interface GigabitEthernet2/0/1

description Downlink from Location 1

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 200

switchport mode trunk


this means vlan 200 is allowed and because native vlan1 on cisco side the frame have 802.1Q tag with vlan-id 200.

what is the meaning of the following:

vlan 200

name "location 0"

ip address

ip helper-address 10.20.0.x

>>>>tagged 2


does it mean tagged with vlan-id 2 ?

Hope to help



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