[124316] in North American Network Operators' Group
RE: Auto MDI/MDI-X + conference rooms + bored == loop
daemon@ATHENA.MIT.EDU (Trey Valenta)
Tue Mar 30 11:35:45 2010
Date: Tue, 30 Mar 2010 08:35:08 -0700
In-Reply-To: <CB659FEF50324640B503095DA13FA9F4F65373@COMM02.annese.local>
From: "Trey Valenta" <trey@arena.net>
To: <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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I had a similar issue in which someone had accidentally looked a Cisco
VoIP phone back into the network. However, I found it strange how often
this would occur and eventually came across this field notice that might
apply to others on the list:
http://www.cisco.com/en/US/ts/fn/610/fn61863.html
Problem Description
Disconnecting power from a locally powered Cisco IP Phone
connected to a non-Power Over Ethernet (POE) Cisco switch may
expose the customer's network to loop back storms that
destabalize the virtual local area network (VLAN). This exposure
can be mitigated by configuring the switches with automatic loop
detection and port recovery.
Notes indicate this normally applies onto to 10Mb connections, but that
there have been reported cases on a 100Mbit network when the VoIP phone
is connected to a "highly sensitive uplink switch".
Trey
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