Administrator Guide

LACP Long Timeout
If there is a LACP protocol running on an interface, the user needs to have the LACP long timeout configured, if LACP short timeout is
configured, ISSU will not take place.
Spanning Tree
When spanning tree is enabled, user needs to have BPDU guard configured 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 traffic loss with respect to L3 ISSU during warmboot or upgrade to a different
switch image.
BGP
Warmboot uses BGP graceful restart functionality to achieve hitless L3 traffic 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 traffic will be forwarded based on the running configuration.
ACL
All user ACL data are stored in a persistent storage before the warmboot. When the system comes back up again, the configuration would
be played and verified 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 configurations 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 configuring ACL with range of ports (having exact match in
configured range profiles), 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 traffic 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
configured in a peer interface to ensure that no ARP/ND ages out when the device is in warmboot.
CoPP
Control Plane Policing (CoPP) in Dell EMC Networking OS provides a method for protecting CPU bound control plane packets by policing
packets punted to CPU with a specified rate and from undesired or malicious traffic.
CoPP is implemented using:
• Rate shapers in CPU port scheduling nodes for queue based shaping
• Rate limiters in egress ACL for protocol based limiting
• Protocol to queue mapping
• Configuring CPU queue length
The user will need to configure the boot-type to warmboot under the reload-type configuration mode. Warmboot is a system reload
technique where the NPU will not restart. Only the CPU is restarted to bring up the upgraded software. Software upgrade ISSU, is the
typical use case for warmboot. Since BCM chip is already up and running while the software is restarted, there should not be any traffic
outage during warmboot. However, since the CPU is restarted during the warmboot process, control plane traffic drop will be observed
and the same would resume post warmboot.
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In-Service Software Upgrade