Brocade FastIron Ethernet Switch Stacking Configuration Guide - Manual (Page 42)

At least one port of a trunk must be connected. If multiple ports of a trunk are connected, they must be
connected to the same trunk of other unit. For example, it is invalid that the two ports of a trunk
connect to two different units, or to different trunks of the same unit. Wrong connection might result in
stacking formation failure or other problems. Some invalid connections still form a stack but with
forwarding problems. Stack probe packets use the first connected port of a stacking trunk. So, as long
as the first connected port of a trunk is connected properly, a stack can form. However, packet
forwarding may not work for some streams that are hashed into the wrongly connected trunk port. In
such case, periodical background diagnosis task could detect wrong connections in about 20 minutes,
and it prints error messages.
Configuration notes for ICX 6610 stack topologies
• ICX 6610 devices do not allow users to change "stack-ports" configuration. Secure-setup sets the
endpoints of a linear FCX stack to data ports, but it does not do so for ICX 6610.
• ICX 6610 devices support up to 120 user-configured or LACP trunks. IDs 121-124 are reserved
for peri-trunk in mixed stacking.
NOTE
ICX 40 Gbps and 4 x 10 Gbps ports cannot be used as data ports, even when stacking is not enabled.
In standalone mode, they drop all packets, except stacking probe packets. Secure-setup and unit
replacement can therefore still discover a standalone unit.
Periodic background stack diagnosis for ICX 6610 devices
After a stack forms, the system periodically probes the topology to check the connections between
units of this stack. It can detect the following errors. The purposes are to detect user's connection
problem and hardware failures. Error messages are printed about every 10 minutes. If there is no
printout, there is no problem. This diagnosis runs in the background.
Manually triggering stack diagnosis
You can manually trigger the diagnosis using the show stack connection command.
1. Ports of the same trunk connect to different units.
2. Ports of the same trunk connect to different trunks of the same unit.
3. Sub-ports of the 4 x 10 Gbps are down.
4. One end of a 10 Gbps port is up and the other end is down.
5. Communication problems between units of the stack
The most common connection error is connecting a 40 Gbps port to a 4 x10 Gbps port. They use
the same type of cable. In such case, the system might show one end is up, and one end is down.
The stack cannot form, and the periodical background diagnosis task won't run at all.
Another connection error is that the two cables of a trunk go to different units, or to different trunks
of the same unit as in case 1 and 2. A stack might still form in these cases. But it may cause an
internal forwarding loop, or have forwarding problems.
Cases 3 to 5 are due to hardware failures or software problems.
For example, the active unit console pops up the following messages if sub-ports of 4 x10 Gbps
are down. The stack should still work because of trunks. If all sub-ports of 4 x10 Gbps are down,
Configuration notes for ICX 6610 stack topologies
40 FastIron Ethernet Switch Stacking Configuration Guide
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