In Service Software Upgrade - Cisco Catalyst 4500 Series Configuration Manual

Chapter 1 Product Overview

In Service Software Upgrade

SSO requires the same version of Cisco IOS on both the active and standby supervisor engines. Because
of version mismatch during an upgrade or downgrade of the Cisco IOS software, a Catalyst 4500 series
switch is forced into operating in RPR mode. In this mode, after the switchover you can observe
link-flaps and a disruption in service. This issue is solved by the In-Service Software Upgrade (ISSU)
feature that enables you to operate in SSO/NSF mode while performing software upgrade or downgrade.
ISSU allows an upgrade or downgrade of the Catalyst IOS or IOS XE images at different release levels
on the both the active and standby supervisor engines by utilizing the Version Transformation
Framework between the stateful components running on each supervisor engine.
For details on Cisco IOS ISSU, refer to
Upgrade Process."
For details on Cisco IOS XE ISSU, refer to
Software Upgrade Process."
IPv6
IPv6 provides services such as end-to-end security, quality of service (QoS), and globally unique
addresses. The IPv6 address space reduces the need for private addresses and Network Address
Translation (NAT) processing by border routers at network edges.
For more information about IPv6 services supported on the Catalyst 4500 series switch, see
"Support for IPv6."
Multicast Services
Multicast services save bandwidth by forcing the network to replicate packets only when necessary and
by allowing hosts to join and leave groups dynamically. The following multicast services are supported:
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ANCP Client —ANCP Multicast enables you to control multicast traffic on a Catalyst 4500 switch
using either ANCP (rather than IGMP) or direct static configuration on the CLI.
Cisco Group Management Protocol (CGMP) server—CGMP server manages multicast traffic.
Multicast traffic is forwarded only to ports with attached hosts that request the multicast traffic.
Internet Group Management Protocol (IGMP) snooping—IGMP snooping manages multicast
traffic. The switch software examines IP multicast packets and forwards packets based on their
content. Multicast traffic is forwarded only to ports with attached hosts that request multicast traffic.
Support for IGMPv3 provides constrained flooding of multicast traffic in the presence of IGMPv3
hosts or routers. IGMPv3 snooping listens to IGMPv3 query and membership report messages to
maintain host-to-multicast group associations. It enables a switch to propagate multicast data only
to ports that need it. IGMPv3 snooping is fully interoperable with IGMPv1 and IGMPv2.
Explicit Host Tracking (EHT) is an extension to IGMPv3 snooping. EHT enables immediate leave
operations on a per-port basis. EHT can be used to track per host membership information or to
gather statistics about all IGMPv3 group members.
The IGMP Snooping Querier is a Layer 2 feature required to support IGMP snooping in a VLAN
where PIM and IGMP are not configured because the multicast traffic does not require routing.
For information on configuring IGMP snooping, see
Filtering."
Chapter 5, "Configuring the Cisco IOS In-Service Software
Chapter 6, "Configuring the Cisco IOS XE In Service
Chapter 25, "Configuring IGMP Snooping and
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
Layer 3 Software Features
Chapter 52,
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