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89 lines
4.4 KiB
TeX
89 lines
4.4 KiB
TeX
\chapter{Evaluation}\label{ch:evaluation}
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To show that Birdvisu is a usable project, we have tried to use it in several
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network systems, both synthetic and already deployed. Here we summarise our
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experience with using it.
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Because our project is mainly an interactive program, we do not present any
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performance or other measurements. Therefore, we rather focus on the subjective
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feeling of the project and evaluate the design decision from chapter~\ref{ch:design}.
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\section{Gennet}
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Naturally, Gennet, as described in section~\ref{s:gennet} is supported quite
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well. Since we had complete control of the whole network, we could test e.g.
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multi-area OSPF deployment, which is not common in real network systems, as far
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as we are aware.
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However, only small networks can be simulated in Gennet, because each router
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requires disk and memory, which may be quite scarce.
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\section{Our home network}
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At home, the author relies on a dynamic routing to switch between falling
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uplinks and to provide a simple way to address virtual machines across the
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network system. This was one of the reasons we decided to look for
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visualisations of OSPF topology state.
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Since it only spans a single room, this system is even smaller than Gennet,
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containing only three routers and less than 10 networks (the exact number
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depends on which devices are up at the time). We believe that major issues do
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not show up at this scale.
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Naturally, Gennet can be connected to the home network. At that point, our
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approach to laying out vertices starts feeling suboptimal, because edges cross
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unnecessarily often. The connections are clear, however, and this can be
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alleviated by using a fixed layout in a file. In the future, this could be
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addressed by using a force-based approach for the automatic layout.
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\section{Department of Applied Mathematics}
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The department which advised this thesis also uses OSPF in its infrastructure.
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Again, the main purpose is to address containers and virtual machines in the
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system. The topology consists of 5 routers and about 27 networks, most of which
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are stub.
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As in the previous case, the main issue is the automatic vertex layout. Also, since most of the
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networks are stub (and often only contain a single host), the graph could
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position these networks near each other, or even collapse them into one vertex.
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Birdvisu does not unfortunately support this at the moment.
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\section{Czela.net}
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Czela.net~\cite{czelanet} is a network system run by a community of network
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enthusiasts in Čelákovice and the surrounding area. There are about 1600 people
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connected to Czela.net. This is the typical OSPF
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deployment, whose main task is to dynamically provide fallbacks in case of
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outages. It is also an example of a larger network, with 45 routers, 32 transit
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networks and 178 external routes\footnote{Most of these would be stub routes in
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other deployments, but there is little difference from the topology perspective.}.
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Unfortunately, their infrastructure does not use BIRD anywhere and we were not
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able to connect our instance to any of their transit networks. Therefore we
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only tested displaying the topology based on a dump from one of their MikroTik
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routers, which we manually converted to mimic BIRD's format. We believe this
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should not affect the performance much, because the retrieval of data from BIRD
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is only occasional and once BIRD dumps the topology, the procedure is the same
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as with loading the topology from file.
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This turned out to be helpful for both us and Czela.net. We discovered that our
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method of highlighting of costs does not work well with too big range of the
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costs, and on the other hand, we found several misconfigurations in their
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network (some routers had external routes to transit networks, a few networks
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with routing-unaware clients were used as transit), even without any other
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knowledge of their system.
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We did not notice any performance issues when dealing with the topology.
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\bigskip
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Unfortunately, we did not have the opportunity to test in a large network (the
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Czela.net's one is the largest we tested), so we do not really know the limits
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of Birdvisu. Those are even hard to guess, because while we are trying to
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use rather fast algorithms, they are implemented in Python, which can sometimes
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be quite slow, and more importantly, does not support threads well. The heavy
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use of hash tables and indirection can also impair performance.
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Overall, the testing did not discover any important problems with the design of
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Birdvisu, we are only aware of issues related to small parts of the project.
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