PM8000 ring topology RSTP

[NicoleTang]

Hi everyone.

I have read few forums in here in regards to RSTP or ring topology on PM8000 meters.

I am still not sure from the forums whether RSTP has been implemented successfully on site.

I have a site that has just been upgraded to Cisco managed switches, and we have PM8000 meters on site that are daisy-chained in a ring, back to the switch (to occupy 2 ports).

There are 3 loops, and one loop consists of 4 PM8000 meters, another of 5, and another of 10 PM8000.

The meters are connected to just the dedicated VLAN and the meters RSTP are enabled also.

First 2 loops of 4 and 5 PM8000s were connected as a ring without issue. The last loop of 10 PM8000 caused a network wide shutdown. 

I want to know if there is:

1. a limit or number of PM8000 that can be daisy chained in a ring

2. a prefer or specific RSTP or STP protocol to use that works with PM8000

3. maybe firmware fix released? The meters are by the customer and I noticed they varied in firmware from the menus

Appreciate technical advice. Thanks.

[Charles_Murison · Accepted solution]

Hello @NicoleTang ,

1. a limit or number of PM8000 that can be daisy chained in a ring
CM: There is more of a performance limitation rather than protocol limitation. As you increase the number of devices, the amount of time for network to settle when there is a change takes longer.

2. a prefer or specific RSTP or STP protocol to use that works with PM8000
CM: RSTP is the protocol PM8000 meters support. 

3. maybe firmware fix released? The meters are by the customer and I noticed they varied in firmware from the menus
CM: There were changes to RSTP on the meters around the V2.2.0 time range. If you meter is V3.0.0 or newer firmware should not be a factor.

Be sure the meters and switches have RSTP enabled before connecting the meters in a loop. If loop is made before RSTP is enabled, the network will see a storm of traffic and likely have networks not happy.

Regards,

Charles