You can operate QSFP
ports as either 40-Gigabit Ethernet or 4 x10-Gigabit Ethernet modes on Cisco
Nexus 3132 and Cisco Nexus 3172 switches. By default, there are 32 ports in the
40-Gigabit Ethernet mode. These 40-Gigabit Ethernet ports are numbered in a
2-tuple naming convention. For example, the second 40-Gigabit Ethernet port is
numbered as 1/2. The process of changing the configuration from 40-Gigabit
Ethernet to 10-Gigabit Ethernet is called breakout and the process of changing
the configuration from 10-Gigabit Ethernet to Gigabit Ethernet is called
breakin. When you break out a 40-Gigabit Ethernet port into 10-Gigabit Ethernet
ports, the resulting ports are numbered using a 3-tuple naming convention. For
example, the break-out ports of the second 40-Gigabit Ethernet port are
numbered as 1/2/1, 1/2/2, 1/2/3, 1/2/4.
The breakout ports are in administratively enabled state after the breakout of the ports into 4x10G mode or the breakin of
the ports into 40G mode. On upgrade from the earlier releases, the configuration restored takes care of restoring the appropriate
administrative state of the ports.
You can break out the
40-Gigabit Ethernet port into four 10-Gigabit Ethernet ports by using the
10000 command and using a splitter cable to connect to multiple peer
switches. You can break in four 10-Gigabit Ethernet ports to a 40-Gigabit
Ethernet port by using the
40000 command. The configuration change from 40-Gigabit Ethernet to
10-Gigabit Ethernet and from 10-Gigabit Ethernet to 40-Gigabit Ethernet takes
effect immediately. You do not need to reload the switch. A QSFP transceiver
security check is also performed.
When you break out
from 40-Gigabit Ethernet to 10-Gigabit Ethernet, or break in from 10-Gigabit
Ethernet to 40-Gigabit Ethernet, all interface configurations are reset, and
the affected ports are administratively unavailable. To make these ports
available, use the
Release 6.0(2)U5(1), a new QSFP+ 40-Gb transceiver is now supported on the
Cisco Nexus 3000 Series switches. The new QSFP+ (40-Gb) transceiver has a cable
that splits into four 10Gb SFP-10G-LR transceivers. To use it, you need the
port to be in 4x10G mode. If you are using the breakout cable, you need to run
that 40G port in 4x10G mode.
The Cisco Nexus 3000 Series switches will have auto as default speed on all port types. Based on the transceiver type, the client auto-configures the default speeds 40000 and
10000 on QSFP and SFP+ ports respectively. The show running-config command treats speed auto as default port speed. However, you can explicitly configure different speed on these ports.
The ability to break
out a 40-Gigabit Ethernet port into four 10-Gigabit Ethernet ports and break in
four 10-Gigabit Ethernet ports into a 40-Gigabit Ethernet port dynamically
allows you to use any of the breakout-capable ports to work in the 40-Gigabit
Ethernet or 10-Gigabit Ethernet modes without permanently defining them.
For Cisco Nexus 3132Q
switches, when the Ethernet interface 1/1 is in the 40-Gigabit Ethernet mode,
the first QSFP port is active. After breakout, when the Ethernet interface
1/1/1-4 is in the 10-Gigabit Ethernet mode, you can choose to use either QSFP
ports or SFP+ ports. However, both the first QSFP port and the four SFP+ ports
cannot be active at the same time.
When using a QSFP-40G-CR4 on Cisco Nexus 3000 switches, you must configure the default speed as 40G in the auto-negotiation
parameters. Otherwise, the interface may not be able to bring the link up.