Cisco Cisco Nexus 5010 Switch Installation Guide

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Cisco Nexus 5500 Series NX-OS Software Upgrade and Downgrade Guide, Release 7.0(8)N1(1)
In-Service Software Upgrades
Layer-2 Protocols Impact
 lists the ISSU impacts to Layer 2 protocols.
EPP 
During an ISSU process, EPP messages are not received/transmitted on the 
ISSU switch. New ports in FC port channels are not negotiated until the 
ISSU completes. Additionally, FC Trunk Mode changes (E port to TE Port 
and vice versa and the allowed VSAN list) are also not processed.
FCoE NPV Links
When the NPV/FCoE NPV switch is logged into a core switch through an 
FCoE NPV link, it punches heartbeats, FIP keepalives (FKA), toward the 
core switch for its own internal login session and all the host login sessions 
pinned through this FCoE NPV link. This FKA interval of 8 seconds is less 
than the ISSU downtime. Enter the disable-fka command on the core switch 
VFC parameters to ensure that the core switch ignores any FKA events. 
Table 4
ISSU Impact to Fibre Channel and FCoE Services (continued)
Service
Description
Table 5
ISSU Impact to Layer 2 Protocols
Protocol
Description
LACP 
IEEE 802.3ad provides for the default slow aging timers to be transmitted 
once every 30 seconds in steady state and to expire after 90 seconds. An 
ISSU should not impact peers that rely on LACP because the recovery time 
is less than 90 seconds.
Fast LACP timers (hello=1 sec, dead=3 sec) are not supported with a 
nondisruptive ISSU. 
IGMP 
IGMP does not disrupt existing flows of multicast traffic that are already 
present, but new flows are not learned (and are dropped) until an ISSU 
completes. New router ports or changes to router ports are not detected 
during this time. 
DCBX and LLDP 
DCBX uses LLDP to exchange parameters between peer devices. Because 
DCBX is a link-local protocol, when the switch undergoes an ISSU, the age 
time is increased on all ports on the switches and FEXs that are being 
upgraded.
Manual configurations are ignored during this time. 
CDP 
During an ISSU, the time-to-live value is increased (180 seconds) if it is 
less than the recommended timeout value. The configuration is ignored if 
manually specified. 
L2MP IS-IS
Before a switch reboots for an ISSU, the switch transmits Layer 2 IS-IS 
hellos on all interfaces to prevent neighbor switches from marking routes to 
the ISSU switch as down. Any topology changes during this time are also 
not acted upon until the ISSU completes.