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New Member

UC320w VLANs, Subnets, Loops and Broadcast Storm

Hi there,

I'm getting a lot of trouble with setting up the UC320W

I have the following:

* UC320W

* Cisco SF300 Switch

* Billion 7404VNPX Router

UC320W WAN port ( connected to the Router (

UC320W LAN port ( connected to the Switch

Router ( connected to the Switch again

All ports on the switch is setup with untagged VLAN1, and tagged VLAN100 for voice.

Everything seems to work fine, until half-way through the day, there's some sort of network traffic flood that stops the network from working.  All the network interfaces on computers constantly receives large amounts of data and eventually everything stops working.

It appears there's a loop in this network design - the UC320 can get onto the Internet via either the Switch, or the Router.  When a device on the network triggers a L2 broadcasts, the UC320w's WAN port gets it (even though it's on a different IP subnet), and so does its LAN port.

Is this network configuration going to work?  Or do I absolutely need to put the UC320 WAN on a different VLAN, which means getting a router that supports VLANs that can each have its own IP subnet?

Will clearing the Default Gateway from the UC320w's LAN side resolve this issue properly so it only has a single default gateway to get onto the Internet?

Edit: I have tracked it down by using a packet sniffer the storm is caused by an application sending multicast packet which loops infinitely in the network.  Putting Storm Control with the SF300 Switch solved the problem, but is there a way of designing this network?

Thanks in advance,

Peter Huang

New Member

UC320w VLANs, Subnets, Loops and Broadcast Storm

I've experienced this problem as well.

The only solution I have found is putting the UC320's WAN in a separate VLAN (often a "DMZ" port on some firewall/routers) or putting the UC320 on its own public IP separate from the gateway.

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