Our networking team needs to do switch maintenance (hardware and firmware)

Each of our 3270 cluster heads is connected to redundant switch pairs - the ifgrp (aka vif) is setup as a single mode: 

ifgrp create single na01-vif0 e1a e1b

Current status (abbreviated for readability):

na01-vif0: 1 link, transmit 'none', Ifgrp Type 'single_mode' fail 'default'
Ifgrp Status Up Addr_set 
up:
e1b: state up, since 20Jul2012 12:01:50 (00:41:27)
mediatype: auto-10g_sr-fd-up
flags: enabled favored

down:
e1a: state down, since 20Jul2012 12:02:21 (00:40:56)
mediatype: auto-10g_sr-fd-up
flags: enabled unfavored

Q: what are the recommended Netapp steps to preserve uptime with the least disruption  while the networking folks upgrade each switch in turn?

thanks!