Service Manual

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
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 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.
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 traffic loss
might be longer.
6. Warm boot is supported because it enables faster convergence and reduced traffic loss.
7. BGP graceful restart must be configured with GR time left to default (120 seconds) or higher. The BGP hold timer should
be configured as 10 seconds.
8. You must configure 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. Traffic from North-South and South-North nodes are of line rate type.
10. Traffic outage for a planned reboot is less than 30 seconds for 4000 routes of IPv4 and IPv6 traffic for all of the following
traffic 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 configure 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 configured. LACP is enabled between the ToR and leaf nodes, and the LACP long timer is set to the default value. You must
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