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Connecting two VLAN's on HP 4000M switched network

Walter Kramer
Occasional Visitor

Connecting two VLAN's on HP 4000M switched network

15 HP 4000M switches in network
4 VLAN active over al switches.
on every switch the ID's are the same for each VLAN.

I have 1 VLAN for WLAN equipment.
The IP adres of this device's are in the same range as the ip adresses in a other VLAN where the servers are. thers is no IP conflict so i want to connect the two VLAN to communicate.

I first connect two untagged ports of each VLAN on the same switch to each other with a cross cable but that isn't working.

Can some one please help me, don't know if can work.

regards Walter
4 REPLIES
Sergej Gurenko
Trusted Contributor

Re: Connecting two VLAN's on HP 4000M switched network

You solution is not the best.
If I'm understand correctly you are using IP addresses from one subnet (e.g. 192.168.5.0/24) on two VLANs. But addresses did not overlaps (you are using 192.168.5.1-100 on one VLAN and 192.168.5.101-200 on the other VLAN).
Now you want to enable communication between two VLANs.
It is recommended to reconfigure all ports (server and WLAN AP's) to one VLAN. It you want temporary fix you can try to connect separate VLAN ports with a cable, but:
1. Make sure STP does not block the port
2. A lot of early models of HP switches have one, shared per all VLANs SAT table (MAC address table) and do not support same MAC address in more than one VLAN.
Walter Kramer
Occasional Visitor

Re: Connecting two VLAN's on HP 4000M switched network

that is what i've done.

All ports from de AP are in VLAN 4. This VLAN is spread over al HP 4000M switches which are configured in a switch mesh. The mesh connections are all tagged ports. the AP are untagged ports.
In VLAN 1 we have servers, printers and workstations. Also these ports are untagged. The mesh connections are all tagged ports in this VLAN.
The ipadresses of all nodes are in the 172.31.x.x/16 range. And they are unique.

Now i want to communicate from a desktop to a AP (ping) but cannot get any connection. when is put the cable back in a VLAN1 port there is a reply on the ping.

Spanning Tree is nog enabled.

If the switch isn't supporting this feature what can i do ?
Place a router between VLAN1 en VLAN4 and reconfigure the AP to another ip subnet ?
Sergej Gurenko
Trusted Contributor

Re: Connecting two VLAN's on HP 4000M switched network

You need to stick on one of the folowing scenarious:
1. Secure Wireless (WPA+EAP) - connected directly to the LAN without any permiions. Wireless users are the same like local lan attached users.
2. Insecure Wireless (noWEP or WEP) - connected to the LAN through FW/HP_Router_7000+VPN/Whatever. Wireless users are the same like internet users and need to initialize VPN to connect to the LAN resources

Even on the first scenario you can route wireless users (if you fave a router).
With the second you definitely need to put users to the second scenario. In our days wireless authentication/encryption methods are secure enough to select first scenario. in early days the only secure way was VPN over the Wireless.
Walter Kramer
Occasional Visitor

Re: Connecting two VLAN's on HP 4000M switched network

We don't do this for more security but for control the traffic. We first want to know or we can reduce the traffic for the AP with a VLAN.

The AP are all Cisco 350 and 1200 serie