Why is AMP reporting a downstream switch as the upstream switch?

[JuliaOstrowski]

I have two Cisco switches being monitored by AMP where one is upstream of the other, but AMP is reporting the downstream switch as the upstream device. How can I fix this?


In 7.0 the logic used by AMP to identify upstream devices for Cisco switches does not always work with multiple levels of switches. We're working on a more robust solution that will include information from the spanning tree and/or bridge forwarding tables to more accurately determine the upstream device. The following three scenarios describe the current logic, followed by a WORKAROUND below.


In the case of Cisco switches, AMP uses the following logic to determine the upstream device:

A. If a switch has one CDP neighbor that is being monitored by AMP, AMP reports that switch as the upstream device 
B. If a switch has more than one CDP neighbor that is being monitored by AMP, no upstream device is reported 


Scenario 1:
Two switches; both are monitored by AMP:

switch-1 >> switch-2

- if switch-1 is polled first, it will mistakenly report switch-2 as its upstream device
- switch-2 will report no upstream device because AMP will not allow two devices to report each other as their upstream

device . . . upstream
switch-1 : switch-2 (incorrect)
switch-2 : none

To resolve this see WORKAROUND below. 


Scenario 2:
Three switches; all are monitored by AMP...

switch-1 >> switch-2 >> switch-3

- switch-1 will mistakenly report switch-2 as its upstream switch (A)
- switch-2 will report no upstream device (B)
- switch-3 will correctly report switch-2 as its upstream device (A)

device . . . upstream
switch-1 : switch-2 (incorrect)
switch-2 : none
switch-3 : switch-2 (correct)

To resolve the cases for switch-1 and switch-2 see WORKAROUND below. 


Scenario 3:
switch-1 and switch-2 are added to the AMP; switch-3 has not been added yet...

Let's say that switch-1 is correctly reported as the upstream device for switch-2.

device . . . upstream
switch-1 : none
switch-2 : switch-1 (correct)

- when switch-3 is added, switch-2 will now have two CDP neighbors that are being monitored by AMP 
- AMP will change the upstream device for switch-2 from switch-1 to none (B)

device . . . upstream
switch-1 : switch-2 (incorrect)
switch-2 : none
switch-3 : switch-2 (correct)


WORKAROUND
You can set the upstream device field manually on a device's Manage page.

Example:

For switch-2 in the scenarios above...
- Go to the Manage page for switch-2
- In the Settings section, set: Auto Detect Upstream Device: No
- In the drop down list that appears select switch-1 (type the name of the device to search for it in the list; type '-' for --None--)
- Save and Apply
- Apply Changes

Once you've turned off Auto Detect, the upstream device you specify on a device's Manage page will not be changed by AMP.