Reordering Portchannel Frames - Cisco DS-C9216I-K9 Configuration Manual

Chapter 21 Configuring Fibre Channel Routing Services and Protocols
Figure 21-5
Switch 1
In Figure
delivered before Frame 1 and Frame 2.
If the in-order guarantee feature is enabled, the frames within the network are treated as specified below:
•
•
•

Reordering PortChannel Frames

When a link change occurs in a PortChannel, the frames for the same exchange or the same flow can
switch from one path to another faster path.
Figure 21-6
Switch 1
In Figure
delivered before Frame 1 and Frame 2.
When the in-order guarantee feature is enabled, the frames crossing a PortChannel are treated as
specified below:
•
•
•
OL-7753-01
Route Change Delivery
Switch 2
Frame 2
21-5, the new path from Switch 1 to Switch 4 is faster. Hence, Frame 3 and Frame 4 may be
Frames in the network are delivered in the order in which they are transmitted.
Frames which can not be delivered in-order within the network latency drop period are dropped
inside the network.
The number of dropped frames are reduced by slowing down the traffic at the frame source.
Link Congestion Delivery
Frame 2
Frame 4
21-6, the port of the old path (red dot) is congested. Hence Frame 3 and Frame 4 can be
Frames using the old path are delivered before new frames are accepted.
Frames which cannot be delivered in-order, through the old path, within the switch latency drop
period are dropped.
The new frames are delivered through the new path after the switch latency drop period has elapsed.
Switch 3
Frame 1
Frame 4 Frame 3
Switch 2
Frame 1
Frame 3
Cisco MDS 9000 Fabric Manager Switch Configuration Guide
In-Order Delivery
Old path
New path
Switch 4
Old path
New path
21-9