Hi Dude...
Don't know if this helps but maybe it's worth giving it a try:
I found this (after digging thru almost 100000 OID's)
Interfacedescription: [oid("1.3.6.1.2.1.2.2.1.2.x")]
Interfacespeed: [oid("1.3.6.1.2.1.2.2.1.5.x")] bps
One of our 4 Gbps channels pops-up with 4000000000 bps here
Adjusted to 'normal' looks
Interfacespeed: [oid("1.3.6.1.2.1.2.2.1.5.x")/1000000000] Gbps
The mentioned 4 Gbps channels displays this correctly with just simply 4 Gbps.
Maybe it's an option to create a function/probe using the x or the name/description, do some math and tell it in any way to warn when it drops to or below 2 Gbps? I don't know whether the value of Interfacespeed gets updated regularly enough (if it gets updated at all), maybe that changes then get displayed or result in changing state-colours.
I'm afraid you've to create a function/probe for every single channel you want to monitor, unless you've used a naming-convention with some logic..
, then you might have to create only some and use these when applicable.
I haven't found anything that looks like an OID observing which ports are members of the channel.
Added port-channels get a numeric OID-instance at the end of the table, after a reload of the device this will change in something more logic subsequent list. In that case you'll have to adjust some previous found values.
Sometimes it's possible to use the name in these cases, if not, then you'll have to adjust everything to the new value, which is then more or less to be the one exspected after each reload.
Good luck, if you find a better solution I would love to hear it!
Gr,
Minollie