MAP-E refers to
Mapping of Address and Port Encapsulation (MAP-E). The MAP-E feature enables
you to configure mapping rules for translation between IPv4 and IPv6 addresses.
Each mapping of address and port using MAP-E domain uses a different mapping
rule. A MAP-E configuration comprises of one basic mapping rule (BMR), one
default mapping rule (DMR), and one or more forwarding mapping rules (FMRs) for
each MAP-E domain.
A BMR configures the MAP IPv6 address or prefix. You can configure only one BMR per IPv6 prefix. The MAP-E CE uses the BMR
to configure itself with an IPv4 address, an IPv4 prefix, or a shared IPv4 address from an IPv6 prefix. A BMR can also be
used for forwarding packets in such scenarios where an IPv4 source address and source port are mapped into an IPv6 address/prefix.
Every MAP-E node (CE device is a MAP-E node) must be provisioned with a BMR. The BMR prefix along with the port parameter
is used as tunnel source address. You can use the port-parameters command to configure port parameters for the MAP-E BMR.
A DMR prefix which matches with the interface address is recognized as hosts and a DMR prefix with a prefix length of 128
is recognized as the tunnel source address. A border relay IPv6 address is used as the tunnel destination address.
When you boot up a Customer Edge (CE) device for the first time, the CE sends an HTTP request to the rule server to acquire
the MAP-E rules. After the CE receives the MAP-E rules, it saves a copy of the rules in a persistent storage, such as bootflash.
When you reboot the router subsequently, the CE then detects the copy of MAP-E rules in the bootflash, so it does not send
the HTTP request immediately. For a fixed IP in IP, the CE sends the request to the rule server only after the Dynamic Domain
Name System (DDNS) reply is successfully received from the address resolution server.
In a fixed IP in IP, the IP in IP tunnel interface is used instead of a NAT64 configuration. Use the nat64 provisioning mode command to enable the tunnel interface.