Fabric OS Administrator's Guide v7.0.0 (53-1002148-02, June 2011)

Fabric OS Administrator’s Guide 79
53-1002148-02
Lossless Dynamic Load Sharing on ports
4
If ICL ports are connected during a core blade insertion, it is equivalent to adding external E_Ports
which may cause I/O disruption due to reroutes. Lossless DLS, if enabled, takes effect to prevent
I/O disruption.
Traffic flow limitations
The FA4-18 and FR4-18i AP blades, which is supported on the Brocade DCX and DCX-4S, may
continue to experience frame drops after core blade removal or insertion. The path between an
FC10-6, FA4-18 or FR4-18i blade and an FX8-24 blade, or vice versa, experiences I/O disruption
because the FC10-6, FA4-18, and FR4-18i blades do not support this feature.
Configuring Lossless Dynamic Load Sharing
You configure Lossless DLS switch- or chassis-wide by using the dlsSet command to specify that no
frames are dropped while rebalancing or rerouting traffic.
1. Connect to the switch and log in using an account assigned to the admin role.
2. Enter the appropriate dlsSet command to enable or disable Lossless Dynamic Load Sharing.
switch:admin>dlsset --enable -lossLess
switch:admin>dlsset --disable -lossLess
Lossless Dynamic Load Sharing in Virtual Fabrics
Enabling Lossless Dynamic Load Sharing is optional on logical switches in Virtual Fabrics. If you
enable this feature, it must be on a per-logical switch basis and can affect other logical switches in
the fabric. The use of eXtensible Interaction Scenario Language (XISL) must be disabled for
Lossless DLS to be enabled.
How DLS affects other logical switches in the fabric
On a Brocade DCX platform, logical switch 1 consists of ports 0 through 5 in slot 1. Logical switch 2
consists of ports 6 through 10 in slot 1. The Lossless DLS feature is enabled on logical switch 1.
Because ports 0 through 10 in slot 1 belong to a logical switch where Lossless DLS is enabled, the
traffic in logical switch 2 is affected whenever traffic for logical switch 1 is rebalanced.
ATTENTION
Although Lossless DSL is enabled for a specific logical switch, you must have chassis-level
permissions to use this feature.
This effect on logical switch 2 is based on the configuration on logical switch 2:
• If logical switch 2 has IOD enabled (iodSet only), IOD is enforced.
• If logical switch 2 has Lossless DLS enabled, traffic is paused and resumed.
• If logical switch 2 has no IOD (iodReset), traffic is paused and resumed.
To avoid this behavior, it is recommended to define your logical switches as follows:
• Define logical switches that require Lossless DLS at the blade boundary.
• Define logical switches that require Lossless DLS only using supported blades. For example, do
not use blades that support IOD, but do not support Lossless DLS.
For more information on Virtual Fabrics and chassis-level permissions, see Chapter 10, “Managing
Virtual Fabrics”.