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IPv4 address and a port block to the IPv6 address of the B4 element. The DS-Lite host or hosts
behind the B4 router use the mapped public IPv4 address and port block to access the public IPv4
network.
DS-Lite NAT444 supports user tracing for DS-Lite hosts based on the port block.
Figure 62 DS-Lite NAT444
NAT entries
NAT session entry
NAT creates a NAT session entry for a session and creates an address mapping for the first packet in
the session.
A NAT session entry contains extended NAT information, such as interface and translation method.
Subsequent packets of the session are translated by using this entry.
The session management module maintains the updating and aging of NAT session entries. For
information about session management, see Security Configuration Guide.
EIM entry
An EIM entry maps a private address/port to a public address/port. The same EIM entry applies to
subsequent connections originating from the same source IP and port.
An EIM entry ages out after all related NAT session entries age out.
NO-PAT entry
A NO-PAT entry maps a private address to a public address. The same mapping applies to
subsequent connections originating from the same source IP.
A NO-PAT entry can also be created during the ALG process for NAT. For information about NAT with
ALG, see "NAT with ALG."
A
NO-PAT entry ages out after all related NAT session entries age out.
NAT444 entry
A NAT444 entry maps a private IP address to a public IP address and a port block.
NAT444 entries include static and dynamic NAT444 mappings. For information about these
mappings, see "Static NAT444" and "Dynamic NAT444."
IPv4 network
Host
NAT gateway
Log server
Application
server
B4 AFTR
IPv6 network
DS-Lite tunnel
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