UC520 > vlans unreachable when nothing's plugged in?

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Apr 19th, 2010
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I have a strange problem.. I have a UC520 that is at a hosting facility.  I have couple remote users at remote sites connected via VPN using phones behind SR routers.. everything works ok.

My issue is this - I have a small laptop connected to the ethernet port of the UC520 and as soon as I unplug this, phones do not come up.  When I VPN to the UC520 from the outside, I can only ping and not or seems like the vlans are not up when nothing is physically plugged into the ethernet ports.  When I plug the laptop back in, system is up and running again...

1. Has anyone noticed this?

2. Is this by design?

3. If so, is there a workaround?

4. If no workaround, can I plug another device.. such as a phone and will it leave the vlans accessible?

Any help will be appreciated! thanks.

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John Platts Mon, 04/19/2010 - 12:36
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I actually do know a workaround to this problem. This workaround will work for UC520, UC540, SR520, and ISR platforms. The workaround is to add no autostate to the configuration for your Vlan interfaces.


interface Vlan1

no autostate

interface Vlan100

no autostate

You do not need to configure no autostate for your BVI interfaces, Dot11Radio interfaces, or your Integrated-Service-Engine interfaces.

aaronc123 Tue, 04/20/2010 - 08:06
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This is a function in all IOS switches ... In more complex networks, it's real function is deactivate the interface so that routing protocols can adjust.

The "no autostate" is absolutely the way to fix it should you want it to stay up.


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