Brocade Communications Systems manual Symmetric flow control on Brocade ICX 6650 devices

Basic port parameter configuration 2

Displaying flow-control status

The show interface <stack-unit>/<slot>/<port>command displays configuration, operation, and negotiation status where applicable.

For example, issuing the command for 10/100/1000M port 1/1/36 displays the following output.

Brocade# show interfaces ethernet 1/1/36 10GigabitEthernet1/1/36 is up, line protocol is up

Hardware is 10GigabitEthernet, address is 748e.f80c.5f40 (bia 748e.f80c.5f40) Interface type is 10Gig SFP+

Configured speed 10Gbit, actual 10Gbit, configured duplex fdx, actual fdx Member of L2 VLAN ID 1, port is untagged, port state is FORWARDING

BPDU guard is Disabled, ROOT protect is Disabled Link Error Dampening is Disabled

STP configured to ON, priority is level0, mac-learning is enabled Flow Control is enabled

Mirror disabled, Monitor disabled Not member of any active trunks Not member of any configured trunks No port name

MTU 10200 bytes, encapsulation ethernet

300 second input rate: 0 bits/sec, 0 packets/sec, 0.00% utilization

300 second output rate: 96 bits/sec, 0 packets/sec, 0.00% utilization

0	packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 multicasts, 0 unicasts
0	input errors, 0 CRC, 0 frame, 0 ignored
0	runts, 0 giants
1	packets output, 64 bytes, 0 underruns			unicasts
Transmitted 0 broadcasts, 1 multicasts, 0
0	output errors, 0 collisions
Relay Agent Information option: Disabled
Egress queues:		Queued packets	Dropped	Packets
Queue counters
	0	0		0
	1	0		0
	2	0		0
	3	0		0
	4	0		0
	5	0		0
	6	0		0
	7	0		0

Symmetric flow control on Brocade ICX 6650 devices

In addition to asymmetric flow control, Brocade ICX 6650 devices support symmetric flow control, meaning they can both receive and transmit 802.3x PAUSE frames.

By default on Brocade ICX 6650 devices, packets are dropped from the end of the queue at the egress port (tail drop mode), when the maximum queue limit is reached. Conversely, when symmetric flow control is enabled, packets are guaranteed delivery since they are managed at the ingress port and no packets are dropped.

Symmetric flow control addresses the requirements of a lossless service class in an Internet Small Computer System Interface (iSCSI) environment.

Brocade ICX 6650 Administration Guide	37
53-1002600-01