On Thu, Nov 5, 2009 at 1:44 PM, Les Mikesell <lesmikesell@xxxxxxxxx> wrote:
> Larry Brigman wrote:
>>
>>>> You could define a class that runs a script to detect the network
>>>> settings, if it is forced to full duplex it would return true, which
>>>> would then trigger another command to run or config files to get
>>>> copied, if configs are copied after that it could execute another
>>>> command(perhaps snmpset to change the switch config or something).
>>> It's next to impossible to get or set a duplex setting via snmp. And
>>> non-trivial to figure out what switch port is connected to what device -
>>> OpenNMS does a reasonable job but if you activate all of its checks it
>>> can kill things that have full bgp routes.
>>
>> Saw something about this at LinuxCon. CME is using Cisco Discover
>> Protocol and LLDP to figure out the
>> info about the connected port, location, vlan and a bunch of other stuff.
>
> That's interesting, thanks! I was surprised to see that cdpr (from
> epel) would pick up the name/ip/port from a connected Dell PowerConnect
> switch. But then I repeated it using the -v option and it found the
> upstream Cisco instead... The production switches are all Cisco though,
> so this might be a usable hack to permit pre-configuring machines to
> adjust themselves to whatever order the cables happen to be plugged in.
> The duplex option just shows a number and doesn't offer to interpret
> the value, but maybe I can look that up somewhere.
>
cdpr is multicast udp packet. Other devices not Cisco will pass this
on. Other Cisco devices
will drop it since it is really only useful between devices. Other
switch vendors wanted to be
more vendor neutral and came up with the LLDP (Link Layer Discovery
Protocol) which I don't think
is on cheaper switches. The other think about CDPR is that unless the
network admin has explicatlly
turned this off, it is "on" by default in all Cisco gear.
CME's basic usage model was to use this to notify the networking group
about a mis-configuration by
pointing them to the exact switch/port by name and number. They use
nothing but Cisco gear.
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