3com S7906E Manuel De Montage

 

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The term tunnel used throughout this document refers to an IPv4/IPv6 transition tunnel, IPv4 over 

IPv4 tunnel or IPv6 over IPv6 tunnel unless otherwise specified. 

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For information about MPLS TE, refer to MPLS TE Configuration in the MPLS Volume. 

 

The expansion of the Internet results in scarce IPv4 addresses. The technologies such as temporary 

IPv4 address allocation and Network Address Translation (NAT) relieve the problem of IPv4 address 

shortage to some extent. However, these technologies not only increase the overhead in address 

resolution and processing, but also lead to upper-layer application failures. Furthermore, they will still 

face the problem that IPv4 addresses will eventually be used up. Internet Protocol Version 6 (IPv6) 

adopting the 128-bit addressing scheme completely solves the above problem. Since significant 

improvements have been made in address space, security, network management, mobility, and QoS, 

IPv6 becomes one of the core standards for the next generation Internet protocol. IPv6 is compatible 

with all protocols except IPv4 in the TCP/IP suite. Therefore, IPv6 can completely take the place of IPv4.  

Before IPv6 becomes the dominant protocol, networks using the IPv6 protocol stack are expected to 

communicate with the Internet using IPv4. Therefore, an IPv6-IPv4 interworking technology must be 

developed to ensure the smooth transition from IPv4 to IPv6. In addition, the interworking technology 

should provide efficient, seamless information transfer. Currently, multiple transition technologies and 

interworking solutions are available. With their own characteristics, they are used to solve 

communication problems in different transition stages under different environments. 

Currently, there are three major transition technologies: dual stack (RFC 2893), tunneling (RFC 2893), 

and NAT-PT (RFC 2766). 

 

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For related information about dual stack, refer to IPv6 Basics Configuration in the IP Services 

Volume. 

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The S7900E series Ethernet switches do not support NAT-PT. 

 

The IPv6 over IPv4 tunneling mechanism encapsulates an IPv4 header in IPv6 data packets so that 

IPv6 packets can pass an IPv4 network through a tunnel to realize interworking between isolated IPv6 

networks, as shown in 

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