[robocup-small] SSL Vision and Referee Network Configuration

[Andre R.]

In our lab we have different networks to separate traffic and to allow 
an easy plug-and-play for our developers and also to provide them with 
internet access. A major reason for the separation is our wireless 
communication to our robots, which is based on ethernet, but has a very 
limited bandwidth. So we are using multicast routing to send only the 
packets to the wireless base station which are needed there.
We then tried to separate our internal traffic from the official vision 
and referee traffic to keep the delay low. Also no problem with 
multicast routing.

There is only one point that makes multicast routing sometimes 
problematic: The default TTL of a multicast packet is 1. So a usual 
multicast packet arriving at our router will get the TTL decremented to 
0 and will be removed. The only way to increase the TTL is to do it in 
the application layer, in our case the vision software.

As this is not an option for Istanbul, I think we will use a much 
simpler solution with two network interfaces on our main computer. So we 
are prepared for any configuration.

Anyway, I think it would be a good idea for the following competitions 
to announce the settings in advance. The multicast TTL patch for the 
vision can be implemented without any negative sideeffects, so this is 
also an option for the next competitions.

Regards,
Andre


Am 18.06.2011 16:24, schrieb Angelo Gurzoni Jr:
> Andre, the official connection is wired, with an isolated switch (thus an isolated network) for each field.
> For the rest of the configuration (ie, ip range, dhcp mode) we ask the teams to be prepared for any configuration. Of course, the TC and OC will not be using complex configurations in such a simple environment, but be ready to use fixed/dhcp and any range setup on the equipment.
>
> Changes to SSL-Vision source close to the competition are disallowed, so the TTL has to remain the same as in the latest code from SVN. However, you're more than welcome to send the details of the issue you faced so the TC and OC can analyze. What we can say is that this code was used last year without issues.
>
>
>
> Regards
> Angelo
> Sent from BlackBerry
>
> -----Original Message-----
> From: "Andre R."<andre at global-mainframe.com>
> Sender: robocup-small-bounces at cc.gatech.edu
> Date: Sat, 18 Jun 2011 16:12:58
> To:<small-size-tc at informatik.uni-bremen.de>
> Cc:<robocup-small at cc.gatech.edu>
> Subject: [robocup-small] SSL Vision and Referee Network Configuration
>
> Dear TC members,
>
> we are currently setting up our network for the use in Istanbul.
> Unfortunately I could not find any information about the configuration
> of the "official" network (Vision + Referee).
> To minimize setup time I recommend a uniform setting for all official
> networks. The settings should include IP Address Range, Subnet Mask,
> DHCP on/off, default gateways etc.
> By the way, do we have a wired internet connection in Istanbul?
>
> To reduce interferences with the other teams' network (the wired one,
> not wireless) in the official segment we are currently using multicast
> routing in our lab. For that to work, we had to modify the vision code
> to increase the TTL of multicast packets to a value above 1 (we took 32).
>
> Any furher information about the topic would be helpful.
>
> Regards,
> Andre Ryll
> Tigers Mannheim
> Vice Project Leader
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