Ieee 802.3X Flow Control; Switch Fabric - Cisco WS-C4507R Troubleshooting Manual

RST-3508
9805_05_2004_c2
Port
Gi4/7
RST-3508
9805_05_2004_c2
© 2004 Cisco Systems, Inc. All rights reserved. Printed in USA.
Presentation_ID.scr
Stub ASIC Overview
Fans out GigE ports from
•

switch fabric

Up to 8 front-panel ports;
•
10/100, 1000-only, or
10/100/1000
Flow control on gigabit
•
interfaces
Ports can be used in an
•
EtherChannel
Not always oversubscribed
•
e.g. 10/100
© 2004 Cisco Systems, Inc. All rights reserved.

IEEE 802.3x Flow Control

Standards-based mechanism used to control data flow
•
Basic steps
•
1) Data flows to switch
2) Switch congested so "pause" frame sent
3) End station waits required time before sending
4) IOS supervisors support both Tx and Rx pause frames
Gigabit Ethernet
Switch
1. Data Flows
to Switch
3. End Station Waits
Rx-No-Pkt-Buff
0
© 2004 Cisco Systems, Inc. All rights reserved.
GbE to/from
Switch Fabric
Up to 8 Front-Panel
Ports, 10/100/1000
2. Switch Congested
"Pause" Frame Sent
File Server
Required Time
Before Sending
RxPauseFrames TxPauseFrames
35648 4854
43 43 43
PauseFramesDrop
0
44 44 44