[c-nsp] Nexus 7710 BGP hold timer and ISSU

[Yham]

Hi All,

As Nexus 7K platform doesn't support multihop BFD so i have to
use faster the BGP hello and hold timers. When i try to configure BGP
timers to "timers 2 6" (hold time = 6), i get a warning message as below

"% ISSU will be affected if hold time is less than system switchover time
(8 seconds)"

Does it means if hold time is higher than 8 seconds (e.g. timers 3 10 or
timers 5 15), ISSU can be performed in future. I was in impression that if
i make any change in default timers (keepalive 60sec & hold 180sec), ISSU
is not longer an option. Moreover, below highlighted in red seem contrary
statements.  Can someone please clarify?

========================
ISSU

Cisco NX-OS supports in-service software upgrades (ISSU). ISSU allows you
to upgrade software without impacting forwarding.

The following conditions are required to support ISSU:

   - Graceful restart must be enabled (default)
   - *Keepalive and hold timers must not be smaller than their default
   values*

If either of these requirements is not met, Cisco NX-OS issues a warning.
You can proceed with the upgrade or downgrade, but service might be
disrupted.

Note
------------------------------

*Cisco NX-OS cannot guarantee ISSU for non-default timer values if the
negotiated hold time between BGP peers is less than the system switchover
time.*

Source:
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/6_x/nx-os/unicast/configuration/guide/b-7k-Cisco-Nexus-7000-Series-NX-OS-Unicast-Routing-Configuration-Guide-Release-6x/n7k_unicast_config_adv_bgp.html#concept_3126984786C2406680150E527351AA2D

Thanks

YH