Administrator Guide

adjacency settings) is learned and installed before the trac resumes. In a typical network scenario, a trac disconnection of 150 seconds
or more usually occurs. When you employ the optimized booting functionality, the trac outage duration is reduced drastically.
Guidelines for Conguring Optimized Booting Mechanism
Keep the following points and limitations in mind when you congure 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 Conguration mode or by using the reset command in uBoot mode on a switch that is running Dell 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 Networking OS to Release 9.3(0.0) or later. Dell 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
undened.
• 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 trac disruption signicantly, the following conditions apply:
1 When LACP is used between the ToR switch and the adjacent devices, LACP is congured 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.
3 Before performing the planned reload, we recommend that the IPv6 Neighbor Discovery (ND) reachable timer is increased to a value
of 300 seconds or longer on the adjacent devices to prevent the ND cache entries from becoming stale and being removed while the
ToR goes through a CPU reset. This timer can be restored to its prior value after the ToR has completed its planned reload.
4 The BGP protocol on the adjacent devices responds to network (link-state) changes and route advertisements quickly and propagates
these further up the network quickly. You might need to adjust the BGP timers on these devices.
5 Note that fast boot will operate even if some of the preceding conditions are not met. However, the duration of trac loss might be
longer.
6 Warm boot is supported because it enables faster convergence and reduced trac loss.
7 BGP graceful restart must be congured with GR time left to default (120 seconds) or higher. The BGP hold timer should be
congured as 10 seconds.
8 You must congure the LACP long timeout, which is the amount of time that a LAG interface waits for a PDU from the remote
system before bringing the LACP session down, to be higher than the default value.
9 Trac from North-South and South-North nodes are of line rate type.
10 Trac outage for a planned reboot is less than 30 seconds for 4000 routes of IPv4 and IPv6 trac for all of the following trac
directions.
• South-North
• North-South
• East-West
• West-East
To the south of ToR switch, 96 servers can be linked. Up to 8 Multiprocotol BGP (MP-BGP) sessions to the servers are established. You
can congure a minimum of 2 MP-BGP sessions and a maximum of 8 MP-BGP sessions.
To the north of the ToR switch, up to 8 leaf nodes are connected. Up to 8 EBGP sessions for IPv4 and IPv6 for each leaf node are
congured. LACP is enabled between the ToR and leaf nodes, and the LACP long timer is set to the default value. You must congure 96
Flex Hash and Optimized Boot-Up
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