Cisco Systems 3560 Unsupported IPv6 Unicast Routing Features, Limitations

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Catalyst 3560 Switch Software Configuration Guide

OL-8553-06

Chapter 37 Configuring IPv6 Unicast Routing

Understanding IPv6

For information about syslog over IPv6, including configuration procedures, see the “Implementing IPv6

Addressing and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

The HTTP client sends requests to both IPv4 and IPv6 HTTP servers, which respond to requests from

both IPv4 and IPv6 HTTP clients. URLs with literal IPv6 addresses must be specified in hexadecimal

using 16-bit values between colons.

The accept socket call chooses an IPv4 or IPv6 address family. The accept socket is either an IPv4 or

IPv6 socket. The listening socket continues to listen for both IPv4 and IPv6 signals that indicate a

connection. The IPv6 listening socket is bound to an IPv6 wildcard address.

The underlying TCP/IP stack supports a dual-stack environment. HTTP relies on the TCP/IP stack and

the sockets for processing network-layer interactions.

Basic network connectivity (ping) must exist between the client and the server hosts before HTTP

connections can be made.

For more information, see the “Managing Cisco IOS Applications over IPv6” chapter in the Cisco IOS

IPv6 Configuration Library on Cisco.com.

Unsupported IPv6 Unicast Routing Features

The switch does not support these IPv6 features:

• IPv6 policy-based routing

• IPv6 virtual private network (VPN) routing and forwarding (VRF) table support

• Support for IPv6 routing protocols: multiprotocol Border Gateway Protocol (BGP) and Intermediate

System-to-Intermediate System (IS-IS) routing

• IPv6 packets destined to site-local addresses

• Tunneling protocols, such as IPv4-to-IPv6 or IPv6-to-IPv4

• The switch as a tunnel endpoint supporting IPv4-to-IPv6 or IPv6-to-IPv4 tunneling protocols

• IPv6 unicast reverse-path forwarding

• IPv6 general prefixes

Limitations

Because IPv6 is implemented in switch hardware, some limitations occur due to the IPv6 compressed

addresses in the TCAM. These hardware limitations result in some loss of functionality and limits some

features.

These are feature limitations.

• ICMPv6 redirect functionality is not supported for IPv6 host routes (routes used to reach a specific

host) or for IPv6 routes with masks greater than 64 bits. The switch cannot redirect hosts to a better

first-hop router for a specific destination that is reachable through a host route or through a route

with masks greater than 64 bits.

• Load balancing using equal cost and unequal cost routes is not supported for IPv6 host routes or for

IPv6 routes with a mask greater than 64 bits.