![]() ![]() For more information, see If you want to use MapToIPv4 to convert an IPv4 address from IPv6 format to IPv4 format, you must first ensure that you've got an IPv4 address. The IPv4-mapped IPv6 address format is specified in RFC 4291. The IPv4 address is encoded into the low-order 32 bits of the IPv6 address, and the high-order 96 bits hold the fixed prefix 0:0:0:0:0:FFFF. The IPv4-mapped IPv6 address format allows the IPv4 address of an IPv4 node to be represented as an IPv6 address. Any IPv4 addresses must be represented in the IPv4-mapped IPv6 address format which enables an IPv6 only application to communicate with an IPv4 node. The ability to interact with an IPv4 address requires the use of the IPv4-mapped IPv6 address format. So there you would have to use another prefix (meaning the subinterfaces would be in different subnets, which would be the case most of the time) or you would have to statically assign one of them.Dual-stack sockets always require IPv6 addresses. %GigabitEthernet0/1.20: Error: 2001:192:168:12:5054:FF:FE1B:42A8/64 is in use on GigabitEthernet0/1.10īecause the same MAC is used, it would result in the exact same IPv6 address. If you try to do this, you will get the following result: R3#conf tĮnter configuration commands, one per line. So you cannot configure two subinterfaces to use EUI-64 with the same prefix. The only thing to keep in mind is that if you are using subinterfaces, all subinterfaces of the same physical interface will adopt the same MAC address. ![]() But even if you don’t calculate it yourself, you can always see what address has been assigned simply using show commands. Wouldn’t we know what the interface-id was going to be based on the port’s mac address anyways which for all my subinterfaces of gi0/2 they would have the same mac address because it’s technically coming off of the gi0/2 so it would be impossible to use eui-64 right? By using the unique local addresses with a translation mechanism such as NPTv6, you can assign addresses internally as you like while creating the appropriate translation to get on the Internet without fear of conflicting addresses. You can still use them if you use a translation mechanism so the actual address doesn’t appear on the Internet itself, but what if your destination on the Internet just happens to be the same as the IPv6 address you gave to a host on your network (highly unlikely, but possible nonetheless). If you start using global unicast addresses on your devices and you allow them to connect directly to the Internet, (without any kind of translation mechanisms) the local ISP will not necessarily route those addresses because they are not registered to you. Just curious to know how we can make use of unique local unicast addresses?Įssentially, the use of these addresses is that you are free to use them on any internal network without the need to for centralised registration. Cisco IP Addressing: NAT Configuration Guide - NPTv6 Support [Cisco ASR 1000 Series. To find out more about NPTv6 take a look at the following Cisco link. This is a huge improvement to traditional NAT because it avoids many of the problems that NAT traditionally introduced into networking. This readuces the load on network devices and also does not interfere with the encryption of the full IP payload. IPv6-to-IPv6 Network Prefix Translation or NPTv6 isa feature that allows for the translation of IPv6 addresses from one subnet to another without the requirement to rewrite the transport layer headers. However, a better alternative to NAT66 is NPTv6. Now although this is possible, it is not very desirable as you stated as well, because we have the appropriate address space to assign each and every internal device with a global unicast address. ![]() This functions exactly the same way as NAT for IPv4, by translating the IPv6 address as well as manipulating the transport layer ports in order to allow PAT. In order to do so we would employ NAT66, that is Network Address Translation IPv6 to IPv6. Thanks for your kind words! I do my best to be as clear and understandable as possible.Ĭoncerning your question, yes it is possible to apply NAT to unique local IPv6 addresses and translate them to global unicast addresses. ![]()
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