measuring scale

implementation/topologies/4r4h_topo.py

@@ -323,9 +323,9 @@ class FourRoutersFourHosts(CustomTopo):
                     "use_pre_defined_function": True,
                     "separate_definitions": True,
                     "command_pre": ("measure_packet_flow", (
-                        'h1', 'h4', '10.4.0.101', ["r1", "r2", "r3", "r4"], 30, 1, "before_failure", [0, 2000], "Packet flow on all routers before failure", "tcp", 100)),
+                        'h1', 'h4', '10.4.0.101', ["r1", "r2", "r3", "r4"], 30, 1, "before_failure", [0, 3000], "Packet flow on all routers before failure", "tcp", 100)),
                     "command_post": ("measure_packet_flow", (
-                        'h1', 'h4', '10.4.0.101', ["r1", "r2", "r3", "r4"], 30, 1, "after_failure", [0, 2000], "Packet flow on all routers after failure", "tcp", 100)),
+                        'h1', 'h4', '10.4.0.101', ["r1", "r2", "r3", "r4"], 30, 1, "after_failure", [0, 3000], "Packet flow on all routers after failure", "tcp", 100)),
 
                 },
                 "failures": [

thesis/content/basics/resilient_routing.tex

@@ -72,7 +72,8 @@ Operations on the control plane are very thorough as decisions are made based on
 This is the reason why most modern networks will use a combination of mechanisms on the data \emph{and} control plane, e.g. FRR and a global convergence protocol, allowing sub-optimal paths to restore availability while the global convergence protocol provides an optimised routing after some time.
 
 
-\subsection{Fast Recovery Methods} \label{FRM}
+\subsection{Fast Recovery Methods} 
+\label{FRM}
 Fast Recovery Methods are operations that take place on the data plane. A combination of operations on the data \emph{and} control plane inevitably create a delay; while the alternative route was already established in a matter of milliseconds through e.g. FRR, the operation on the control plane, e.g. a controller calculating optimal routings, will take any time in the order of seconds. In this time gap the network uses a sub optimal route for its traffic. 
 
 Loops created by e.g. FRR will affect the network in this time frame and will not only potentially delay traffic but also reserve scarce link capacity on looped routes.

thesis/content/introduction.tex

@@ -13,21 +13,16 @@ Failures in networks will always occur, be it through the failure of hardware, f
 
 Network administrators use a multitude of ways to increase performance, reduce the impact of failures on the network and achieve the highest possible availability and reliability. Two of these methods include the usage of global convergence protocols like Open Shortest Path First (OSPF) (\cite{Moy.041998}) or similar methods, either on the routers themselves or on a controller in a software defined network (SDN), and the usage of Fast Re-Routing (FRR) and Fast Recovery Methods (FRM), which are operations limited to the data contained on a device.
 
-As global convergence protocols are very slow with sometimes taking time on the second scale (\cite{Liu.2013}) to converge, they leave the routing during the time of route calculation to In-network methods like FRR, which will reroute traffic according to pre-defined alternative routes on the network. In some cases however methods like FRR cause routing paths to be longer than necessary, which produces additional traffic on the network and adds delay to transmissions.
+As global convergence protocols are very slow with sometimes taking time on the second scale (\cite{Liu.2013}) to converge, they leave the routing during the time of route calculation to In-network methods like FRR which will reroute traffic according to pre-defined alternative routes on the network. In some cases however methods like FRR cause routing paths to be longer than necessary which produces additional traffic on the network and adds delay to transmissions. 
 
+FRMs like ShortCut (\cite{Shukla.2021}) try to alleviate this issue by removing longer paths from the routings only using data available on the device, bridging the gap between FRR and the global convergence protocol.
 
-- failures in networks will occur undeniably, so they need to be adressed
-- networks in high availability contexts need to recover fast from failures
-- most commonly, a combination of re routing rules on the devices themselves (local fast re-routing) and a global convergence protocol would be used to react to failures
-- local fast re-routing can produce loops and other types of delays and/or additional load on the network, which will continue to 
-burden the network until a global convergence protocol will rewrite rules
-
-- methods like ShortCut will alleviate this burden by removing unnecessary loops fast
+As technologies like ShortCut are relatively current contributions there is not much data evaluating their performance on a network.
 
 
 \section{State of the art}
 
-- there are only a few other methods like ShortCut, coming with their own limitations on applicable network types and compatible fast re-routing mechanisms
+In modern networks many network administrators make use of a combination of FRR and global convergence protocols. Due to this there have been several proposals for optimizations using FRMs like ShortCut, resilient routing layers (
 
 \section{Contribution}