How to Configure and Manage Pause Frames using Flow Control on Dell Networking Force10 switches

Objectives

Definition of Pause Frames

Ethernet Pause Frames allow for a temporary stop in data transmission. A situation may arise where a sending device may transmit data faster than a destination device can accept it. The destination sends a PAUSE frame back to the source, stopping the sender's transmission for a period of time .

The PAUSE frame is defined by IEEE 802.3x and uses MAC Control frames to carry the PAUSE commands. Ethernet pause frames are supported on full duplex only.
 
If a port is over-subscribed, Ethernet Pause Frame flow control does not ensure no-loss behavior.

 

How to enable Flow Control

• rx on -  to process the received flow control frames on this port.
• rx off -  to ignore the received flow control frames on this port.
• tx on -  to send control frames from this port to the connected device when a higher rate of traffic is received.
• tx off -  flow control frames are not sent from this port to the connected device when higher rate of traffic is received.

How to view interface statistics for pause frames
 

You can view the current count of throttles since the last time the counters were cleared with this command:throttles.    as pause framesDell Networking Force10 switches report

Dell#show interface te 0/1
TenGigabitEthernet 0/1 is down, line protocol is down
Hardware is DellEth, address is 00:01:e8:8b:18:bb
    Current address is 00:01:e8:8b:18:bb
Pluggable media not present
Interface index is 1048708
Internet address is not set
Mode of IPv4 Address Assignment : NONE
DHCP Client-ID :0001e88b18bb
MTU 1554 bytes, IP MTU 1500 bytes
LineSpeed auto
Flowcontrol rx off tx off
ARP type: ARPA, ARP Timeout 04:00:00
Last clearing of "show interface" counters 16:48:20
Queueing strategy: fifo
Input Statistics:
     0 packets, 0 bytes
     0 64-byte pkts, 0 over 64-byte pkts, 0 over 127-byte pkts
     0 over 255-byte pkts, 0 over 511-byte pkts, 0 over 1023-byte pkts
     0 Multicasts, 0 Broadcasts, 0 Unicasts
     0 runts, 0 giants, 0 throttles
     0 CRC, 0 overrun, 0 discarded
Output Statistics:
     0 packets, 0 bytes, 0 underruns
     0 64-byte pkts, 0 over 64-byte pkts, 0 over 127-byte pkts
     0 over 255-byte pkts, 0 over 511-byte pkts, 0 over 1023-byte pkts
     0 Multicasts, 0 Broadcasts, 0 Unicasts
     0 throttles, 0 discarded, 0 collisions, 0 wreddrops
Rate info (interval 299 seconds):
     Input 00.00 Mbits/sec,          0 packets/sec, 0.00% of line-rate
     Output 00.00 Mbits/sec,          0 packets/sec, 0.00% of line-rate
Time since last interface status change: 16:46:37