IPv6: masalah proto-41 di router forwarding

Tunneling IPv6 hanya bisa berhasil jika semua router yang di lewati dengan senang hati melalukan protocol number 41 (proto-41) yang resminya adalah IPv6 in IPv4.

Sialnya:

Per Networking and Firewalls:

• Traffic that uses a protocol other than TCP, UDP, and ICMP is blocked, unless explicitly allowed through Protocol Forwarding.

Per Protocol Forwarding:

Google Compute Engine supports protocol forwarding for the following protocols:

• AH: Specifies the IP Authentication Header protocol.
• ESP: Specifies the IP Encapsulating Security Payload protocol.
• SCTP: Specifies the Stream Control Transmission Protocol.
• TCP: Specifies the Transmission Control Protocol.
• UDP: Specifies the User Datagram Protocol.

Hence, a Protocol Forwarding rule needs to be for one of the following IP protocol numbers:

• 51 (AH)
• 50 (ESP)
• 132 (SCTP)
• 6 (TCP)
• 17 (UDP)

The Protocol Forwarding page makes it clear that other protocol numbers, such as 41 (6in4) are not supported:

Note: This is an exhaustive list of supported protocols. Only protocols that appear here are supported for protocol forwarding.