Users Guide

and trac will be treated seamlessly, during reload. After the reload is complete, the running-cong and startup-cong will be compared
and if there is a dierence, the device will be programmed based on the startup-cong.
L2 ISSU
This section deals with L2 ISSU related information.
The following changes are required by ISSU for L2:
LACP Long Timeout
If there is a LACP protocol running on an interface, the user needs to have the LACP long timeout congured, if LACP short timeout is
congured, ISSU will not take place.
Spanning Tree
When spanning tree is enabled, user needs to have BPDU guard congured in the interfaces.
MAC Address Table
During warmboot MAC address table will be stored and they are retrieved after warmboot is complete.
L3 ISSU
This feature has been designed to ensure that there is no trac loss with respect to L3 ISSU during warmboot or upgrade to a dierent
switch image.
BGP
Warmboot uses BGP graceful restart functionality to achieve hitless L3 trac forwarding. During warmboot, the BGP sessions do not
cease and remain ESTABLISHED until hold time (default 180 seconds). The device sends an open message as a restarting router post
warmboot. All graceful-restart capable BGP peers acknowledge the restart, marking the learnt routes from the device as stale. New BGP
sessions are then formed. Any change in the network (route, Interface addition/deletion) during warmboot are handled at the hardware
post recovery.
Static Routes
All entries are stored in a persistent storage during warmboot, the trac will be forwarded based on the running conguration.
ACL
All user ACL data are stored in a persistent storage before the warmboot. When the system comes back up again, the conguration would
be played and veried with the values stored in the persistent storage to identify any stale entries. The ACL counters would be reset during
the warmboot. After the system completes the warmboot and reaches a steady state, new congurations would be programmed into the
hardware. The same behavior applies for L2, L3, V6 ingress and egress ACLs.
FP Range Checker
With aclrange feature enabled, The number of cam entries occupied by conguring ACL with range of ports (having exact match in
congured range proles), will not be changed before and after warmboot.
ARP and Neighbor Discovery
ARP and Neighbor Discovery will store and restore the ARP and ND entries to achieve hitless trac forwarding . During warmboot, ARP
and ND entries will be stored and when the system is booting up, the entries will be restored. After the warmboot, the refresh time is set to
3 minutes, so that stale entries can be removed after the refresh. ipv6 nd disable-reachable-timer should be mandatorily
congured in a peer interface to ensure that no ARP/ND ages out when the device is in warmboot.
In-Service Software Upgrade
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