Administrator Guide

To delete the configured flex hash setting, use the no version of the command.
Configuring Fast Boot and LACP Fast Switchover
Configure the optimized booting time functionality by performing the following steps.
1. Enable the system to restart with optimized booting-time functionality enabled.
CONFIGURATION mode
DellEMC(conf)#reload-type fastboot
2. Configure fast boot on a port-channel on both the nodes that are members of a port-channel in order to enable the physical ports to
be aggregated faster. You can configure the optimal switchover functionality for LACP even if you do not enable the fast boot mode
on the system. This command applies to dynamic port-channel interfaces only. When applied on a static port-channel, this command
has no effect. If you configure the optimized booting-time capability and perform a reload of the system, the LACP application sends
PDUs across all the active LACP links immediately.
INTERFACE (conf-if-po-number) mode
DellEMC(conf-if-po-number)#lacp fast-switchover
Optimizing the Boot Time
You can reduce the booting time of a switch by using the fast boot feature. With the reduced time that is taken to reboot the switch,
upon a manually-initiated reload or an expected restart of the device, there is minimal disruption in the traffic that is managed by the
switch. Traffic outage is lowered considerably (reduced to approximately 25 seconds in certain network deployments) when you enable
this optimization method while booting the device. By reducing the duration of traffic loss, the subscriber sessions are processed and
preserved in an effective and seamless way.
You can configure this capability on the switch that is deployed as a top-of-rack (ToR) switch. The ToR switch is the single point of
connection to the network for servers in that rack. This functionality of minimized reload time is supported in a network deployment in
which the servers are connected through a ToR, leaf and spine unit or configuration setup. An exterior border gateway protocol (EBGP)
session exists between the ToR and leaf switch units, and between the leaf and spine units or nodes.
Booting Process When Optimized Boot Time Mechanism is
Enabled
When device running Dell EMC Networking OS earlier than Release 9.3(0.0) is reloaded, the CPU and other components on the board are
reset at the same time. Therefore, the control plane and the forwarding plane are impacted immediately. After the system boots up and
re-initializes, the interfaces come up, control plane protocols are reestablished, and the network topology information (such as routes,
adjacency settings) is learned and installed before the traffic resumes. In a typical network scenario, a traffic disconnection of 150 seconds
or more usually occurs. When you employ the optimized booting functionality, the traffic outage duration is reduced drastically.
Guidelines for Configuring Optimized Booting Mechanism
Keep the following points and limitations in mind when you configure the fast boot capability:
• Fast boot is supported only when you perform an expected, stipulated reload by using the reload-type normal-reload
command in Global Configuration mode or by using the reset command in uBoot mode on a switch that is running Dell EMC
Networking OS Release 9.3(0.0) or later, or when you perform a planned upgrade (and not an abrupt or unexpected shutdown) from
an older release of Dell EMC Networking OS to Release 9.3(0.0) or later. Dell EMC recommends that you do not downgrade your
system from Release 9.3(0.0) to an earlier release that does not support the fast boot functionality because the system behavior is
unexpected and undefined.
• Fast boot uses the Symmetric Multiprocessing (SMP) utility that is enabled on the Intel CPU on the device to enhance the speed of
the system startup. SMP is supported on the device.
For the fast boot feature to reduce the traffic disruption significantly, the following conditions apply:
1. When LACP is used between the ToR switch and the adjacent devices, LACP is configured on these adjacent devices with a timeout
value of 90 seconds or longer.
2. BGP timers between the ToR switch and adjacent devices are set to high values (for example, a hold timeout of 180 seconds) unless
BGP graceful restart is used.
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Flex Hash and Optimized Boot-Up