Service Manual

Table Of Contents
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 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
In-Service Software Upgrade
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