About Reordering Portchannel Frames; About Enabling In-Order Delivery - Cisco AP776A - Nexus Converged Network Switch 5020 Configuration Manual

In-Order Delivery
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
In Figure
may be delivered before Frame 1 and Frame 2.
If the in-order guarantee feature is enabled, the frames within the network are treated as follows:
•
•

About 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 26-6
Switch 1
In Figure
be delivered before Frame 1 and Frame 2.
The in-order delivery feature attempts to minimize the number of frames dropped during PortChannel
link changes when the in-order delivery is enabled by sending a request to the remote switch on the
PortChannel to flush all frames for this PortChannel.
Both switches on the PortChannel must be running Cisco SAN-OS Release 3.0(1) for this IOD
Note
enhancement. For earlier releases, IOD waits for the switch latency period before sending new frames.
When the in-order delivery guarantee feature is enabled and a PortChannel link change occurs, the
frames crossing the PortChannel are treated as follows:
•
•
Frames that cannot be delivered in order through the old path within the switch latency drop period are
dropped. See the

About Enabling In-Order Delivery

You can enable the in-order delivery feature for a specific VSAN or for the entire switch. By default,
in-order delivery is disabled on switches in the Cisco MDS 9000 Family.
Cisco MDS 9000 Family CLI Configuration Guide
26-14
26-5, the new path from Switch 1 to Switch 4 is faster. In this scenario, Frame 3 and Frame 4
Frames in the network are delivered in the order in which they are transmitted.
Frames that cannot be delivered in order within the network latency drop period are dropped inside
the network.
Link Congestion Delivery
Frame 2
Frame 4
26-6, the port of the old path (red dot) is congested. In this scenario, Frame 3 and Frame 4 can
Frames using the old path are delivered before new frames are accepted.
The new frames are delivered through the new path after the switch latency drop period has elapsed
and all old frames are flushed.
"Configuring the Drop Latency Time" section on page
Chapter 26 Configuring Fibre Channel Routing Services and Protocols
Switch 2
Frame 1
Frame 3
Old path
New path
26-17.
OL-18084-01, Cisco MDS NX-OS Release 4.x