You'd download the MIB file on the support site in the software section.
https://esupport.extremenetworks.com/
With an MIB browser you'd search thru the MIB...
https://community.extremenetworks.com/extreme/topics/mib-to-oid-with-description
Below the full information of the MIB entry MIB: IF-MIB::ifOperStatus.1001 (1.3.6.1.2.1.2.2.1.8.1001):
In short it's the interface status (up/down) of interface#1001
iso.org.dod.internet.mgmt.mib-2.interfaces.ifTable.ifEntry.ifOperStatus
1.3.6.1.2.1.2.2.1.8
ifOperStatus OBJECT-TYPE
SYNTAX Integer {
up(1),
down(2),
testing(3),
unknown(4),
dormant(5),
notPresent(6),
lowerLayerDown(7) }
MAX-ACCESS Read Only
STATUS Current
DESCRIPTION
The current operational state of the interface. The
testing(3) state indicates that no operational packets can
be passed. If ifAdminStatus is down(2) then ifOperStatus
should be down(2). If ifAdminStatus is changed to up(1)
then ifOperStatus should change to up(1) if the interface is
ready to transmit and receive network traffic; it should
change to dormant(5) if the interface is waiting for
external actions (such as a serial line waiting for an
incoming connection); it should remain in the down(2) state
if and only if there is a fault that prevents it from going
to the up(1) state; it should remain in the notPresent(6)
state if the interface has missing (typically, hardware)
components.
::= { ifEntry 8 }
-Ron