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Question : 3Com 5500 VLAN's
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Hello Experts,
We are adding a new building to our network topology and have a couple routing questions. A quick summary of our current network
(Corp Buildings 172.16.10.0)
(Cisco 2900)
Transparent VLAN from Cox Communications
(Cisco 2900)
(Main Building 192.168.0.0)
The new building is next to our main building connected via fiber cable. We purchased (2) 5500 layer 3 switches to connect the new building. In the future we want to add a 5500 to Corp building and take out the Cisco 2900s form our network.
But Im going back and forth on how to connect the two switches to our current network with minimal broadcast traffic to the new building. Here are my thoughts
(Cisco 2900)
(Main Building 192.168.0.0)
Gig connection to existing 3com 4400 (Trunk?) I would need to create vlan 2?
(3com 5500)
Vlan 2
Fiber (Trunk?)
Vlan 2
(3com 5500)
(New Building)
Internal VLAN 9 IP 192.168.9.0 255.255.254.0
The new building will have its own DHCP/DC/DNS but users will need to access share drives / web sites from the existing 192.168.0.0 network.
What would be the optimal way to configure this?
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Answer : 3Com 5500 VLAN's
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Device 1:
- Don't include port 25 in VLAN 1. Ideally if possible make it a "routed port", ie like a normal (layer 3) port on a router, & assign an IP to port 25 that's not a part of any other subnet (let's say 10.88.22.1/30). If that's not possible with the 5500, then set port 25 to a different VLAN that doesn't exist anywhere else, say VLAN 200. Set the IP of this device on VLAN 200 to our example IP of 10.88.22.1 255.255.255.252 --> in Cisco syntax:
interface vlan 200
ip address 10.88.22.1 255.255.255.252
- Routes: For any subnets you want to reach at Building 9, point routes to Device 2 (in Cisco syntax): ip route 192.168.9.0 255.255.254.0 10.88.22.2
Device 2:
- Setup port 25 same as Device 1, but assign IP: 10.88.22.2 255.255.255.252
- Routes:
A) If Building 9 will be getting to the Internet & all points beyond through the main building, simply set your default gateway to Device 1's IP (10.88.22.1).
Again in Cisco parlace: ip route 0.0.0.0 0.0.0.0 10.88.22.1
B) If Building 9 will instead have its own Internet connection, for any subnets you want to reach at Main site, point routes as necessary to Device 1 (10.88.22.1), such as for 192.168.0.0 255.255.252.0.
- IP for this device *on VLAN 90* could be 192.168.9.1 (in Cisco parlace, set the IP of VLAN 90 to this IP). This IP of course would be the default gateway for any host on VLAN 90.
This meets your goals, since B9 will be on a different subnet, separated by a layer 3 ("router-like") device, the 5500. With the links between the 2 5500's either set as "router" ports or at least on their own completely separate VLAN, broadcasts on either side won't be propagated across the fiber. And with routes setup as outlined above, hosts in B9 will be able to access the Main site & vice versa.
Try not to make this more complicated than it is.... Treat the 5500's just like you would a pair of (VLAN-capable) routers, which is what they essentially are.
>B9 = 192.168.9.0 255.255.254.0
Hopefully that subnet mask is a typo? As I said before, you _really_ should avoid having VLANs larger than 254 hosts. But, that's up to you .
cheers
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