Cisco Cisco IOS Software Release 12.2(33)SRE

12.2(28)SB 

The ISSU feature was introduced.

12.2(31)SGA

Support for ISSU was introduced on the Cisco Catalyst 4500 series platform.

Support for the following new features was added on the Cisco Catalyst 4500 series platform:

Dynamic Host Configuration Protocol (DHCP) snooping

EtherChannel - Port Aggregation Protocol (PagP) and Link Aggregate Control Protocol 
(LACP)

IEEE 802.1x protocol

IEEE 802.3

Internet Group Management Protocol (IGMP) snooping 

IP Host

Port security

Spanning-Tree Protocol (STP)

12.2(31)SB2

Support for the following new features were added to the 12.2(31)SB2 release:

ISSU - Dynamic Host Configuration Protocol (DHCP) on-demand address pool (ODAP) 
client/server

ISSU - DHCP proxy client

ISSU - DHCP relay on unnumbered interface

ISSU - DHCP server

ISSU - First Hop Routing Protocol (FHRP) - Gateway Load Balancing Protocol (GLBP)

ISSU - Intermediate System-to-Intermediate System (IS-IS)

ISSU - Quality of Service (QoS)

12.2(33)SRB1

Support for the following new features were added to the 12.2(33)SRB1 release: 

ISSU - ARP

ISSU - ATM 

ISSU - Frame Relay 

ISSU - GLBP 

ISSU - HDLC

ISSU - HSRP 

ISSU - IS-IS

ISSU - Multitopology routing (MTR)

ISSU - PPP/MLP

ISSU - QoS

ISSU - RIB/VRF

ISSU - SNMP