On Fri, 26 May 2006, Rich Adamson wrote:
Dr. Michael J. Chudobiak wrote:
Blaming the 3com switch is very likely to be the wrong root cause. High
probability the 3com was not configured properly for the phone.
Just curious - what configuration issues did you have in mind?
A partial list of issues that we've seen in the last 12 years include:
- auto negotiation of duplex settings (mismatch)
- spanning tree disabling ports for first 30 seconds after any link state
change (some attached devices don't like that)
- spanning tree loops that end up isolating devices from the backbone
(spanning tree is usually implemented by the manufacture by default)
- various switch manufacturers have licensed/implemented cisco's discovery
protocol, and the user doesn't realize some equipment attached to such ports
actually use the cdp data to change port configuration, while other devices
might barf on those packets.
- assumptions that all switches operate at wire speeds and "buffer" packets
(eg, no such thing as a switch buffer; packets will be dropped under high
load conditions)
- distributing vlans across multiple switches where assumptions are made
relative to what happens when two or more vlans are transporting traffic
volumes that when combined exceed a trunk's port speed (eg, don't forget
about broadcast storms).
- switch forwarding tables that are too small (eg, workgroup switches) and
the table fills, essentially turning the switch into a hub
- bad assumptions relative to rate limiting broadcast and multicast packets,
and how that impacts normal traffic.
- etc, etc.
If any of these issues makes a _phone reboot or lockup_ then that is a
serious flaw with the phone.
I migh expect a cheapy grandstream to have issues but expensive snom
should really do better.
-Dan
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