[++doc] background and co.

doc/Background.tex

@@ -103,22 +103,70 @@ the two protocols for this thesis are:
   \label{fig:ipv4header}
 \end{figure}
 % ----------------------------------------------------------------------
-\section{\label{background:arpndp}ARP and NDP, ICMP ICMP6- FIXME}
-Required for finding host.
-ARP \cite{rfc826} who has
-NDP similar -- add traces here
-
-being able to answer to error messages
-MTU / pmtu
-
-Also add: IPv6 is closed / no arp
-ICMP6 \cite{rfc4443}
-%\LaTeX{}
+\section{\label{background:arpndp}ARP and NDP, ICMP and ICMP6}
+While IPv6 and IPv4 are primarily used as a ``shell'' to support
+addressing for protocols that have no or limited addressing support
+(like TCP or UDP), protocols like ARP \cite{rfc826} and NDP
+\cite{rfc4861} provide support for resolving IPv6 and IPv4
+addresses to hardware (MAC) addresses. While both ARP and NDP are only
+used prior to establishing a connection on and their results are
+cached, their availability is crucial for operating a switch.
+Figure \ref{fig:arpndp} illustrates a typical address resolution process.
+\begin{figure}[h]
+  \includegraphics[scale=0.3]{arp-ndp}
+  \centering
+  \caption{ARP and NDP}
+  \label{fig:arpndp}
+\end{figure}
+The major difference between ARP and NDP in relation to P4 are
+\begin{itemize}
+\item ARP is a separate protocol on the same layer as IPv6 and IPv4,
+\item NDP operates below ICMP6 which operates below IPv6,
+\item NDP contains checksums over payload,
+\item and NDP in ICMP6 contains optional, non referenced option fields
+  (specifically: ICMP6 link layer address option).
+\end{itemize}
+ARP is required to be a separate protocol, because IPv4 hosts don't
+know how to communicate with each other yet, because they don't have a
+way to communicate to the target IPv4 address (``The chicken and the
+egg problem'').
+NDP on the other hand already works within IPv6, as every IPv6 host is
+required to have a self-assigned link local IPv6 address from the
+range \texttt{fe80::/10} (compare RFC4291\cite{rfc4291}). NDP also
+does not require broadcast communication, because hosts automatically
+join multicast groups that embed parts of their
+IPv6 addresses (\cite{rfc2710}, \cite{wikipedia:_solic}). This way the
+collision domain is significantly reduced in IPv6, compared to IPv4.
 
-DNS64 \cite{rfc6174}
+As seen later in this document (compare
+\ref{results:netpfga:checksum}), the requirement to generate checksums
+over payload poses difficult problems for some hardware targets. Even
+more difficult is the use of options within ICMP6. Figure shows a
+typical layout of a neighbor advertisement messages.
+\begin{figure}[h]
+  \includegraphics[scale=0.3]{icmp6ndp}
+  \centering
+  \caption{ICMP6 option fields}
+  \label{fig:icmp6ndp}
+\end{figure}
+The problem arises from the layout of the options, as seen in the
+following quote:
+\begin{quote}
+Neighbor Discovery messages include zero or more options, some of
+which may appear multiple times in the same message.  Options should
+be padded when necessary to ensure that they end on their natural
+64-bit boundaries.\footnote{From RFC4861.}
+\end{quote}
 
-IPv6 only network experiences \cite{rfc6586}
-Solicited-node multicast address\cite{wikipedia:_solic}.
+ICMP6 and ICMP are primarily used to signal errors in
+communication. Specifically signalling that a packet is too big to
+pass a certain link and needs fragmentation is a common functionality
+of both protocols. For a host (or switch) to be able to emit ICMP6 and
+ICMP messages, the host requires a valid IPv6 / IPv4 address.
+Without ICMP6 / ICMP support path mtu discovery (\cite{rfc1191},
+\cite{rfc8201}) does not work and the sender needs to determine
+different ways of finding out the maximum MTU on the path.
+% ok -- need to separate backgroun and results
 % ----------------------------------------------------------------------
 \section{\label{background:transition}IPv6 Translation Mechanisms}
 While in this thesis the focus was in NAT64 as a translation mechanism,
@@ -185,6 +233,10 @@ information to choose from for translation, complex parsers or even
 cryptographic methods are required for it. That reduces the
 opportunities of protocol dependent translation
 % ----------------------------------------------------------------------
+\subsection{\label{background:transition:dns64}DNS64 - FIXME}
+
+DNS64 \cite{rfc6174}
+% ----------------------------------------------------------------------
 \subsection{\label{background:transition:prefixnat}Prefix based NAT -
   FIXME}
 Explain how it works in general

doc/Conclusion.tex

@@ -18,6 +18,8 @@ Many misleading
 
 \section{\label{conclusion:P4}P4}
 
+NDP parsing problem
+
 checksumming a frequent problem and helper
 
 Many possibilities

doc/Results.tex

@@ -36,7 +36,11 @@ Stateful : no automatic removal
 \section{\label{results:jool}Jool}
 
 
+% ----------------------------------------------------------------------
 \section{\label{Results:NetPFGA}NetFPGA}
+\subsection{\label{results:netpfga:checksum}Checksum computation}
+\subsection{\label{results:netpfga:general}to be named}
+
 
 Trace files
 \begin{verbatim}

doc/appendix.tex

@@ -2370,9 +2370,12 @@ Describe your task.
 %---------------------------------------------------------------------------------------------------------
 \printnomenclature
 
+\abbrev{ARP}{Address resolution protocol}
 \abbrev{ASIC}{Application-specific integrated circuit}
 \abbrev{FGPA}{Field-programmable gate array}
 \abbrev{LPM}{Longes prefix matching}
+\abbrev{MTU}{Maximum transfer unit}
+\abbrev{NDP}{Neighbor Discovery Protocol}
 \abbrev{NAT}{Network Address Translation}
 \abbrev{NAT64}{Network Address Translation from / to IPv6 to / from IPv4}
 \abbrev{RIR}{Regional Internet Registry}

doc/graphviz/arp-ndp.dot

@@ -0,0 +1,25 @@
+digraph G {
+    node [ shape="box"];
+   rankdir="LR";
+
+
+
+    v6host1 [ label="IPv6 only host (fe80::1 and 2001:db8::1)"];
+    v6host2 [ label="IPv6 only host (fe80::2 and 2001:db8::2)"];
+    v4host1 [ label="IPv4 only host (192.0.2.1)"];
+    v4host2 [ label="IPv4 only host (192.0.2.2)"];
+
+    subgraph cluster_v6 {
+
+    v6host1->v6host2 [ label="ICMP6 neighbor solicitation, who has 2001:db8::2? [Multicast]" ];
+    v6host2->v6host1 [ label="ICMP6 Neighbor Advertisement: 2001:db8::2 has 00:00:0a:00:00:42' [Unicast]" ];
+
+    }
+    subgraph cluster_v4 {
+
+    v4host1->v4host2 [ label="ARP who has 192.0.2.2? [Broadcast]" ];
+    v4host2->v4host1 [ label="ARP 192.0.2.2 is at 00:00:0a:00:00:22' [Unicast]" ];
+
+    }
+
+}

doc/graphviz/icmp6ndp.dot

@@ -0,0 +1,13 @@
+digraph G {
+    node [ shape="box"];
+
+
+    ipv6 [ label="IPv6" ]
+    icmp6 [ label="ICMP6" ]
+    icmp6ns [ label="ICMP6 Neigbor Advertisement" ]
+    icmp6nsll [ label="ICMP6 Neigbor Solicitation Link layer option" ]
+    icmp6other [ label="More option fields" ]
+
+    ipv6->icmp6->icmp6ns->icmp6nsll->icmp6other;
+
+}