TABLE 2: IPv6—THE CHALLENGER

Advantages

Standard defines end-to-end semantics Large 128-bit address space Hierarchical address space allocation    includes country information Packet service extensions part of    IPv6 header definition Auto-configuration support Advanced routing and broadcasting Mobile device support standard Native VPN/IPsec support Quality-of-service support Supported by latest DNS and DHCP    servers

Disadvantages

Incompatible with IPv4 Requires new stacks Limited but growing stack availability Difficult to add support to existing IPv4    hardware-based routers and line cards Limited but growing application support