Do I have a loop in this stack?

[Neal_Howard]

I am a brand new owner of a pair of X670V-48t switches and am a complete newb to Extreme switches and XOS but I've got over 15 years of experience with Cisco Catalyst switches and am well-versed in those.

My pair of X670V-48t switches are equipped each with a VIM4-40G4X module and are connected together as a stack with a pair of QSFP+ cables.

I had Extreme's tech support assist me with configuring the stack and was advised to connect the VIM4 ports on the back of each unit as Port 3 on Switch A to port 4 of Switch B and Port 4 of Switch A to Port 3 of Switch B.

Tech Support remoted into my PC and configured the switch stacking configs for me and the stack seems to be functioning, but part of the behavior of the switches troubles me.

All the blue LEDs on the connected ports of the VIM4 modules themselves and the blue "ST" LEDs on the front panels, and also all the link LEDs of any Ethernet port connected to a computer all blink rapid-fire, machine-gun-like *in unison* at a very high rate of speed even when there is no real network traffic. In the Cisco world, where I'm much more familiar, this unison-LED-blinking generally indicates very bad juju... that a loop exists or that some kind of broadcast or multicast packet storm is happening. Even with no computers connected to the switches, or any connections to the rest of my network (just the two switches connected to each other via the QSFP+ cables and isolated from the rest of the world) the blue LEDs on the back and front of the units still blink rapid-fire in unison.

Is this normal behavior for a stacked pair of switches in the Extreme switch world?

Here is my stacking configs:

Slot-1 SANBONE-10G.1 # show stacking
Stack Topology is a Ring
Active Topology is a Ring
Node MAC Address Slot Stack State Role Flags
------------------ ---- ----------- ------- ---
*00:04:96:97:de:07 1 Active Master CA-
00:04:96:97:de:0b 2 Active Backup CA-
* - Indicates this node
Flags: (C) Candidate for this active topology, (A) Active Node
(O) node may be in Other active topology
Slot-1 SANBONE-10G.2 # show stacking configuration
Stack MAC in use: 02:04:96:97:de:07
Node Slot Alternate Alternate
MAC Address Cfg Cur Prio Mgmt IP / Mask Gateway Flags Lic
------------------ --- --- ---- ------------------ --------------- --------- ---
*00:04:96:97:de:07 1 1 100 CcEeMm-Nn --
00:04:96:97:de:0b 2 2 90 CcEeMm-Nn --
* - Indicates this node
Flags: (C) master-Capable in use, (c) master-capable is configured,
(E) Stacking is currently Enabled, (e) Stacking is configured Enabled,
(M) Stack MAC in use, (m) Stack MACs configured and in use are the same,
(i) Stack MACs configured and in use are not the same or unknown,
(N) Enhanced protocol is in use, (n) Enhanced protocol is configured,
(-) Not in use or not configured
License level restrictions: (C) Core, (A) Advanced edge, or (E) Edge in use,
(c) Core, (a) Advanced edge, or (e) Edge configured,
(-) Not in use or not configured
Slot-1 SANBONE-10G.3 # show stacking-support

Stack Available Ports
Port Native Alternate Configured Current
----- ----------------- ---------- ----------
1 Yes 47 Native N/A
2 Yes 48 Native N/A
stacking-support: Enabled N/A

Flags: * - Current stack port selection

Slot-1 SANBONE-10G.4 # show stacking stack-ports
Stack Topology is a Ring
Slot Port Select Node MAC Address Port State Flags Speed
---- ---- ------ ----------------- ----------- ----- -----
*1 1 Native 00:04:96:97:de:07 Operational CB 40G
*1 2 Native 00:04:96:97:de:07 Operational C- 40G
2 1 Native 00:04:96:97:de:0b Operational C- 40G
2 2 Native 00:04:96:97:de:0b Operational CB 40G
* - Indicates this node
Flags: (C) Control path is active, (B) Port is Blocked
Slot-1 SANBONE-10G.5 #

[Paul_Russo]

Hey Neal

It doesn't appear that there is a loop. I would expect the pps to be much higher on a 10G or 40G loop. If you are still concerned I would recommend re-opening up the TAC case and have them look deeper into the stats.

Hope that helps
P

[Neal_Howard]

Here's both a "show ports stack-ports 1:1,1:2,2:1,2:2 utilization" and "... statistics"

Link Utilization Averages Tue Oct 14 09:18:12 2014
Port Link Rx Peak Rx Tx Peak Tx
State pkts/sec pkts/sec pkts/sec pkts/sec
================================================================================
1:1 A 0 1 25 39
1:2 A 17 36 1 2
2:1 A 1 2 16 33
2:2 A 24 35 0 1

Port Statistics Tue Oct 14 09:20:48 2014 82 Port Link Tx Pkt Tx Byte Rx Pkt Rx Byte Rx Pkt Rx Pkt
State Count Count Count Count Bcast Mcast ================================================================================
1:1 A 10328976 1269304279 506419 47705262 11 8277

1:2 A 1063383 108022632 9551832 1901909882 284346 16553

2:1 A 9551876 1901915496 1063383 108022650 301135 264301

2:2 A 506419 47705262 10329021 1269309889 13 24844

[Stephane_Grosj1]

Hi,

Can you try if the show ports stack-ports statistics can help? Not sure if that will work on non native SummitStack ports.

If so, I'm not aware of a MIB for that, so monitoring needs to go through a script.

Regards,
Stephane

[Neal_Howard]

All ports shown under the "show port util" command show 0 pkts/sec on ports in the "Ready" link state, and single digits on ports with "Active" state.

Is there some way of looking at the utilization of the physical ports of the VIM4 modules which make up the actual stack linkages?

[Paul_Russo]

Hello Neal

From what you posted everything looks correct. Both nodes are seen in the stack and one is master and the other is backup as I would expect. It also shows that you have a ring architecture which shows that all of the ports are in use.

As for the LEDs it is possible that there is a traffic storm of some short maybe multicast etc. If you do a show port util and then hit the space bar a few times it should show the utilization in % of bandwidth. It should also show the max value.

what are those values?

P