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Topic: About 464XLAT

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Post #1
mark5
20 May 2015, 18:54

Good day.

I'd like to ask how I should use 464xlat. There are no documentations and forum topics regarding this. Although the usage says:

464xlatcfg <name> [ifname] [ipv6prefix] [ipv4addr] [ipv6addr]

Do I need a 1:1 NAT mapping between the host and XLAT like the logical setup below?
[host] ---- [NAT] ---- [XLAT]


If so, does this mean that if I have the following details:
Machine A (NAT, XLAT)
    192.168.0.1, 192.168.0.2, ..., 2001:db8::1, 2001:db8::2, ...
Machine B (host behind NAT)
    1.2.3.4
Where: 1.2.3.4 is already mapped to 192.168.0.2


The correct usage for the situation should be:

464xlatcfg test_xlat eth0 2001:db8:: 192.168.0.2 2001:db8::2

Please correct me if I am wrong. Thanks.

Post #2
CyrusFF
20 May 2015, 19:15

464XLAT (CLAT) is not what you think it is. If you have an IPv6 only network (like some mobile operators do) which offers NAT64 and DNS64 you can use 464 to make legacy IPv4 devices be able to access the IPv4 internet.

See https://tools.ietf.org/html/rfc6877 for technical details, we only support the CLAT side at the moment. This is similar to what e.g. Android and the upcoming Windows 10 support.

Configuration is as usual:

config interface clat
    option proto 464xlat

the rest is usually auto-detected.

Post #3
mark5
27 May 2015, 10:28

I have read the document. Would NAT64 suffice? I'm thinking about using tayga for my setup. Maybe I'll try with DNS64 some time as RFC6877 stated that DNS64 is used for stateful translations.

Will test out the figure below based Page 7 of RFC6877:

                                           Destination IPv4 address
                                          +----------------------------+
                                          | Global IPv4 address        |
                                          | assigned to IPv4 server    |
                               +--------+ +----------------------------+
                               |  IPv4  |  Source IPv4 address
                               | server | +----------------------------+
                               +--------+ | Global IPv4 address        |
                                   ^      | assigned to IPv4 PLAT pool |
                                   |      +----------------------------+
                               +--------+
                               |  PLAT  | Stateful XLATE(IPv4:IPv6=1:n)
                               +--------+
                                   ^
                                   |
                              (IPv6 cloud)
         Destination IPv6 address
        +--------------------------------------------------------------+
        | IPv4-embedded IPv6 address                                   |
        | defined in Section 2.2 of RFC 6052                           |
        +--------------------------------------------------------------+
         Source IPv6 address
        +--------------------------------------------------------------+
        | IPv4-embedded IPv6 address                                   |
        | defined in Section 2.2 of RFC 6052                           |
        +--------------------------------------------------------------+
                              (IPv6 cloud)
                                   ^
                                   |
                               +--------+
                               |  CLAT  | Stateless XLATE(IPv4:IPv6=1:1)
                               +--------+
                                   ^       Destination IPv4 address
                                   |      +----------------------------+
                               +--------+ | Global IPv4 address        |
                               |  IPv4  | | assigned to IPv4 server    |
                               | client | +----------------------------+
                               +--------+  Source IPv4 address
                                          +----------------------------+
                                          | Private IPv4 address       |
                                          | assigned to IPv4 client    |
                                          +----------------------------+

          Figure 3: Case of Enabling Only Stateless XLATE on CLAT

Thanks for your help.

(Last edited by mark5 on 27 May 2015, 10:35)

Post #4
jordi.palet
9 Mar 2017, 10:52

HI Mark, have you been able to get this working?

The discussion might have continued from here.