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Finish Design/stateful NAT64

Nico Schottelius 3 years ago
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  2. BIN


@ -231,17 +231,33 @@ entries for translating from IPv4 to IPv6. Our P4/BMV2 offers the
highest degree of flexibility, as it provides support for invidual
entries based on table entries and LPM table entries.
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\section{\label{design:statefulnat64}Stateful NAT64 - FIXME: write}
- controller selects "outgoing" IPv4 address range => base for sessions
- IPv4 addresses can be "random" (in our test case), but need
to be unique
- switch does not need to know about the "range", only about
- on session create, controller selects "random" ip (ring?)
- on session create, controller selects "random port" (next in range?)
- on session create controller adds choice into 2 tables:
incoming, outgoing
\section{\label{design:statefulnat64}Stateful NAT64}
Similar to stateless NAT64, the design of stateful NAT64 depends on
the features of the invidual implementation. As pointed out in section
\ref{background:transition:statefulnat64}, stateful NAT64 is very
similar to stateless NAT64, with the main difference being an
additional stateful table that helps to create 1:n mappings.
We use different approaches within the implementations
to solve this problem:
\item For P4/BMV2 and P4/NetPFGA a python controller handles packets
that don't have a table entry, sets the table entry in the P4 switch
and inserts the original packet afterwards back into the switch.
\item With tayga we rely on the Linux kernel NAT44 capabilities
\item Jool implements its own stateful mechanism based on a port
All methods though operate in a very similar fashion: A ``controller''
inspects the IPv6 packet and depending on the source address,
destination address, protocol (TCP, UDP,
ICMP, ICMP6, etc.) and the protocol ID (source / destination TCP/UDP
port, ICMP identifier) it selects an outgoing IPv4 address, and source
port or ICMP identifier.
In case of Jool and Tayga this decision is based on a session table
inside the Linux kernel, in case of P4 this decision is based on a
session table inside the python controller. While the Jool and Tayga
both support cleaning up old session entries,
our P4 based solution does not support this feature at the moment.
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Development of the thesis took place on a software emulated switch


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