No, that isn't the case, it is a dual ring, so there are paths

FPC0->FPC1->FPC2->FPC0
FPC0->FPC2->FPC1->FPC0

There are ways to tell which is the "active" path through the rings, as I
stated before, I think one path is mainly "active" and one is mainly passive.
I don't know if just disabling one VCP port will work.

But I guess there is a KB on it.
https://kb.juniper.net/InfoCenter/index?page=content&id=KB17821&actp=search

So, we could failover the active path to the other ring.
Or set one of the VCP ports to disable.

Should we do a 'virtual-chassis active path failover' event sometime?

On Tue, Sep 20, 2016 at 08:07:00AM -0500, Jeremy Lumby wrote:
> So if I understand correctly from your "show virtual-chassis active-topology" below, all traffic from the 4500 to the 4200 is going via the 4550?  And if that is the case, is there an easy way in the software that we could tell it to have return traffic from the 4200 to the 4500 also go via the 4550?  This would allow us to easily test to see if it is the specific cable that runs from the 4200 to the 4500.
>
> -----Original Message-----
> From: MICE Discuss [mailto:[log in to unmask]IPHOUSE.NET] On Behalf Of Doug McIntyre
> Sent: Tuesday, September 20, 2016 12:24 AM
> To: [log in to unmask]
> Subject: Re: [MICE-DISCUSS] EX4200 (1G Switch) Packet Loss -> 10G Participants
>
> On Mon, Sep 19, 2016 at 11:01:00PM -0500, Jeremy Lumby wrote:
> > This leads me to wonder if there is possibly an issue with the stacking modules, or they are being saturated.
> ...
>
> Your understanding of the vc port speeds is correct.
>
> The VCP ports are built into the EX4200 and EX4500. The EX4550 has addon
> cards that do those functions. We can devote a port to VCP functionality
> instead, but it'll be a 10G limit instead of 32G
>
> The VCP ports are 32Gbps single direction in each port. So in the dual-ring
> the cables have are 32Gbps in each direction.
>
> You can see which ports are connected to what. (FPC0 is the EX4500,
> FPC1 is the EX4200, FPC2 is the EX4550).
>
> show virtual-chassis active-topology
> fpc0:
> --------------------------------------------------------------------------
>   Destination ID        Next-hop
>
>   1                    2(vcp-1.32768)  1(vcp-0.32768)
>
>   2                    2(vcp-1.32768)
>
> fpc1:
> --------------------------------------------------------------------------
>   Destination ID        Next-hop
>
>   0                    0(vcp-0.32768)  2(vcp-1.32768)
>
>   2                    2(vcp-1.32768)
>
> fpc2:
> --------------------------------------------------------------------------
>   Destination ID        Next-hop
>
>   0                    0(vcp-255/2/0.32768)
>
>   1                    1(vcp-255/2/3.32768)
>
>
>
> You can monitor each of the VCP ports on each of the members. I don't think
> we are close to saturation.
>
> request session member 1
> (ie. rlogin to the EX4200 switch).
>
> monitor int vcp-0
> Interface: vcp-0, Enabled, Link is Up
> Encapsulation: Virtual-Chassis-Interface, Speed: 32000mbps
> Traffic statistics:                                              Current delta
>   Input bytes:               25685118521                               [12138]
>   Output bytes:              27856843010                               [13204]
>   Input packets:                33377693                                  [16]
>   Output packets:               33371644                                  [16]
> Error statistics:
>   Input errors:                        0                                   [0]
>   Input drops:                         0                                   [0]
>   Input framing errors:                0                                   [0]
>   Carrier transitions:                 0                                   [0]
>   Output errors:                       0                                   [0]
>   Output drops:                        0                                   [0]
>
>
> vcp-1 on FPC1 is much less usage. Still zero error stats. All switches
> show zero error stats on any of the respective VCP port status.
>
> I suppose further troubleshooting could be to replace the VCP cables
> one by one coming out of the EX4200.
>
> Its too bad that we've got the quad fiber expansion in the EX4200,
> another test could be to put the dual 10G expansion in it, and make
> those VCP ports and make the VC fabric over those ports instead. But
> we've got 3 member ports lit on that quad 1G fiber.
>
>
>
> --
> Doug McIntyre                            <[log in to unmask]>
>                     ~.~ ipHouse ~.~
>        Network Engineer/Provisioning/Jack of all Trades

--
Doug McIntyre                            <[log in to unmask]>
                    ~.~ ipHouse ~.~
       Network Engineer/Provisioning/Jack of all Trades