[sdnog] P2P link

[Nishal Goburdhan]

On 20 Jul 2020, at 6:39, الفاتح محمد حامد wrote:

> greeting
> I want to deliver an internet service to a College that is 4 km away 
> from
> the data center via wireless and I currently have two options, which 
> is
> installation via
>  nanostation m5
> or
>  tp link cpe510
> Note that the college is very large and the number of users can reach 
> 1000
> Do these devices meet the purpose or not?
> And if not, what are the alternative solutions?

hi,

that’s really going to depend on how much capacity you require, and, 
what frequency you plan to use.  my personal bias would be the 
nanostation, but i don’t like tp-link (for a long list of reasons that 
are not relevant to your use-case, but are still enough to make me avoid 
the platform).

but, there are two separate components here;  there’s the
# i need wireless termination points (radios) ie. something for the p2p 
wireless link that is 4km away, and,
# i need a router at the site

you _want_ to separate out the two functions;  that is, have something 
to terminate the link, and and a separate router for the university, and 
*not* try to do this all on one device.  remember that you’ll need 
network separation (staff, users, networking devices) etc, and that will 
need separate security policies, etc.  that’s not the sort of thing 
that either of these devices will do particularly well.

choosing hardware is not difficult;  and the best way to do this, is to 
have a functional specification for:
# what you *need* the device to do today  (ie. bare minimum feature-set)
# what you *want* the device to do   (ie.  the cool things you want to 
do)
# what you will need the device to do for the next three years   (or for 
how long your accountants keep hardware “on the books”)
# and finally, adapting all that to your budget

it might sound like a boring exercise, but it’s a good habit to form.  
if you can do this consistently, your colleagues, and management know 
that you have put thought into the process;  and when you get to larger 
organisations later, you won’t be able to make purchases without 
having this sort of process peer-reviewed.
also, don’t be misguided by one person’s horror/success story.  
everyone has their favourites, and their own set of needs.  makings your 
own lists allows you to focus on what is important to *you* and your 
application.

finally, something else that *will* emerge from this process, is the 
“where is your design?” question.  that’s really key to the entire 
process.  good design won’t need to change over time;  so if you plan 
the network adequately well, and need to swap this to fibre in the 
future, you should really only need to “upgrade” the equipment for 
higher capacity and not redo the entire layout.  so, spend the time now, 
design it carefully (and correctly - and ask here, if you need 
help/ideas/stuck on a concept), and only *then* think about what 
hardware you should be buying.
and, remember the golden rule in design:  design according to best 
principles;  not according to what a hardware vendor says they are 
willing to support ..

so, where’s your design?  :-)

—n.