Users Guide

Interoperation of Applications with Fast
Boot and System States
This functionality is supported on the platform.
The following sections describe the application behavior when fast boot functionality is enabled:
LACP and IPv4 Routing
Prior to the system restart, the system implements the following changes when you perform a fast boot:
The system saves all dynamic ARP entries to a database on the flash drive.
A file is generated to indicate that the system is undergoing a fast boot, which is used after the system comes
up.
After the Dell Networking OS image is loaded and activated, and the appropriate software components come
up, the following additional actions are performed:
• If a database of dynamic ARP entries is present on the flash drive, that information is read and the ARP
entries are restored; the entries are installed on the switch as soon as possible. At the same time, the
entries are changed to an initial (“aged out”) state so that they are refreshed (and flushed if not learnt
again). The database on the flash card is also deleted instantaneously.
• The system ensures that local routes known to BGP are imported into BGP and advertised to peers as
quickly as possible. In this process, any advertisement-interval configuration is not considered (only
during the initial period when the peer comes up).
If you do not configure BGP GR, you must configure the peering with BGP keepalive and hold timers to be as
high as possible (depending on your network deployment and the scaled parameters or sessions) to enable
the connection to be active until the system re-initializes the switch, causing the links to adjacent devices to
go down. If the BGP sessions are disabled before the re-initialization of the switch occurs because of the peer
timing out, traffic disruption occurs from that point onwards, even if the system continues to maintain valid
routing information in the hardware and is capable of forwarding traffic.
LACP and IPv6 Routing
The following IPv6-related actions are performed during the reload phase:
• The system saves all the dynamic ND cache entries to a database on the flash card. After the system
comes back online, and the Dell Networking OS image is loaded and the corresponding software
applications on the system are also activated, the following processes specific to IPv6 are performed:
• If a database of dynamic ND entries is present on the flash, the information is read and the ND entries
are restored (to the IPv6 subsystem as well as the kernel); the entries are installed on the switch as
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