| Daniel,
Here's what the MIB says about "Link Test".
>erptrMauLinkTestAdminStatus OBJECT-TYPE
> SYNTAX INTEGER {
> enabled(1),
> disabled(2)
> }
> ACCESS read-write -- ** Non-volatile
> STATUS mandatory
> DESCRIPTION
> "Link test functions detect certain types of media faults on
> point-to-point link segments connecting pairs of link-type MAUs
> (e.g. 10BASE-T, 10BASE-F, FOIRL). This object controls the link
> test function implemented by some link-type MAUs.
>
> Setting this object to enabled(1) causes the MAU to enable its
> link test function.
>
> Setting this object to disabled(2) causes the MAU to disable
> its link test function. Disabling a MAU's link test function
> can be useful for compatibility to link-type MAUs which do not
> implement a link test function.
>
> Link-type MAUs which implement link test functions but do not
> support software control of the functions allow this object to
> be set to enabled(1). A badValue error is returned if this
> object is set to any other value.
>
> Coax type MAUs (e.g. 10BASE5, 10BASE2) or any other MAUs which
> do not implement link test functions return disabled(2) when
> this object is read. These MAUs allow this object to be set to
> disabled(2) but return a badValue error if the object is set to
> any other value.
>
> Note: The state of this object is preserved when the repeater
> undergoes a power-up reset."
> REFERENCE
> "Reference IEEE 802.3 Std., sections 9.9.2.1 and 14.2.1.7."
> ::= { erptrMauEntry 4 }
|
| Daniel,
Shawn nailed it. What DEC calls Link Test Admin Status is a
software interface to the low-level hardware Link Integrity feature.
Link Integrity (when enabled on a port or a MAU) is a test pulse
sent out the Tx pair of a repeater port. (I'm talking at the repeater
chip level; what the user sees on the front panel are just media
interface ports, such as ones that accomodate 8-pin modular jacks).
If the pulse is not received on the Rx pair after a short delay,
indicating a link integrity failure, the repeater chip
STOPS REPEATING DATA TO THAT PORT. The port LED on the front panel
also gets shut off (the port LED is an indication of link integrity,
not of port state).
Link integrity MUST be set to the same state (enabled or disabled)
on both sides of a link. Old computing devices and some really old
MAUs and repeaters don't support link integrity, so link integrity
is seen as disabled.
It sounds like your PCs may have fallen into the latter category.
Perhaps your MAUs that attached the 10BaseT cable to your PC's
NIC cards have link integrity disabled, or do not have the setting
available. (Some MAUs have internal jumpers, others have DIP switches
or "slider" switches).
Also, for those ports which you said worked, what was the state
of Link Test Admin Status for those repeater ports?
Link Integrity is one of the primary things network managers define
RMON alarms on. If link integrity changes state on any repeater
port in a topology, it's lets you know that a device has failed,
someone has unplugged something, or sabotage has occurred.
Link Integrity is a network manager's friend, and should only
be disabled when the device on the other side of the link
doesn't support the feature (for backwards compatibility to
older devices which don't support link integrity).
John Gillis
clearVISN
|
|
Hello together,
Thanks for Your detailed Explanations.
>Also, for those ports which you said worked, what was the state
>of Link Test Admin Status for those repeater ports?
The state was enabled. Strange is, that most of the Ports work
correctly. If i change Link Test Admin Status to disable, than
enable again, unlug, then plug in again the same Cable with
nothing changed then it works. It just needs a "kick" to get
running. Maybe there is a low threshhold on the Signal, that
causes this go -nogo effekt.
But we go now Onsite to Customer Site to check, wheter the
Symptoms are exactly like we had it here in our Lab.
Maybe somebody else have had similar Symptoms bevore?
Thanks,
Daniel MCS Switzerland
|