From 3051695878c6ca8655516ba4573dff3d9dff450c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophile=20Bastian?= <contact@tobast.fr>
Date: Tue, 21 Jul 2020 15:12:40 +0200
Subject: [PATCH] Tentative "Babel protocol extension" section

---
 slides.tex | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/slides.tex b/slides.tex
index 00d1533..d0be3fe 100644
--- a/slides.tex
+++ b/slides.tex
@@ -100,9 +100,72 @@ draft-bastian-babel-v4ov6}}
         \item IPv6 has \alert{link-local} and \alert{automatic addresses}
             (SLAAC)
             \begin{itemize}
-                \item no need for DHCP or IP configuration \emph{at all}!
+                \item no need for DHCP or IP addresses configuration \emph{at all}!
             \end{itemize}
     \end{itemize}
 \end{frame}
 
+\begin{frame}[fragile]{Supported in Linux since 5.2}
+    \begin{block}{d1566268 -- 2019-04-05 -- ipv4: Allow ipv6 gateway with ipv4 routes}
+        \quad{}Add support for \lstbash{RTA_VIA} and allow an IPv6 nexthop for v4
+        routes.
+    \end{block}
+
+    \vspace{1em}
+
+    \begin{itemize}
+        \item{} Usually, add a v4 route with
+            \begin{lstlisting}[language=iproute, numbers=none]
+# ip route add 10.42.0.0/16 via 10.40.0.42 dev eno1
+            \end{lstlisting}
+
+        \item{} v4-over-v6 (recent kernel):
+            \begin{lstlisting}[language=iproute, numbers=none]
+# ip route add 10.42.0.0/16 via inet6 fe80::a0de:baf:b39b dev eno1
+            \end{lstlisting}
+    \end{itemize}
+
+\end{frame}
+
+\section{Babel protocol extension}
+
+\begin{frame}{Advertising v4-over-v6 routes}
+    \textbf{An IPv4 interface} never announces v4-over-v6 routes
+
+    \vspace{1em}
+
+    \textbf{A v6-only interface}
+    \begin{itemize}
+        \item{} \alert{Installs a v4 route} nevertheless when receiving it
+        \item{} \alert{Announces a v4-over-v6 route} for each v4 route
+    \end{itemize}
+\end{frame}
+
+\begin{frame}{Introducing a new AE}
+    In Babel, \alert{Address Encodings} (AEs) define the type of address/prefix
+    contained in a TLV.
+    \begin{itemize}
+        \item IPv4 address
+        \item IPv6 address
+        \item link-local IPv6 address
+        \item[$\bigstar$] \alert{v4-over-v6 address}
+    \end{itemize}
+\end{frame}
+
+\begin{frame}{Backwards compatibility}
+    \textbf{With older implementations}
+    \begin{itemize}
+        \item Ignore v4-over-v6 routes
+        \item No state updates missed
+    \end{itemize}
+
+    \vspace{2em}
+
+    \textbf{With older kernels}
+    \begin{itemize}
+        \item Won't advertise a route that cannot be locally set
+        \item In babeld, detect kernel version
+    \end{itemize}
+\end{frame}
+
 \end{document}