Also worth mentioning that a lot of OSPF documentation available on the
Internet, makes assumptions that were valid in 2002 or so...  When a
typical router had a lot less DRAM and CPU. Such as a Cisco 3725/3745 or
even something smaller like a 2621.

Probably still true if you're trying to do OSPF on very small Mikrotiks but
not as much of a concern in the modern era. The main bottleneck in routing
platforms is FIB size and RAM for BGP tables, not so much OSPF.



On Thu, Jun 7, 2018 at 1:15 PM, Dennis Burgess <dmburg...@linktechs.net>
wrote:

> This is a “unanswerable” question.  In honesty, you can have 20k routes in
> OSPF and it be responsive so the routing platform does not have a limit.
> The number of routers, is another issue, if you have 500 routers all fiber
> connected and they don’t go up/down much, then no big deal, however, if
> they do go up down quite a bit or you don’t know how to manage them, then
> yes this can be a factor. The last thing is convergence time, if you have
> lots of fiber, and/or well connected routers, then that is not a major
> issue, break part of your network and see how long it takes for a reroute,
> if that is acceptable, then again no worries.
>
>
>
> Now OSPF books, state that you should have no more than 75-100 routers,
> but I have read things that state no more than 50 and I have other networks
> that have more than 500. So..  Again, it’s not a good answerable question.
>
>
>
> However, my suggestion is to look at your network as a whole and see if
> there is some kind of logic, to splitting up your OSPF domains.  You can
> use OSPF areas, or you can use BGP between them.  But there needs to be a
> good, constant method to splitting your network like that.  Keep in mind
> that using defaults will cause traffic to shift, etc, so you need to plan
> plan plan…
>
>
>
> Just my two cents.
>
>
>
>
>
>
>
> *Dennis Burgess, Mikrotik Certified Trainer *
>
> Author of "Learn RouterOS- Second Edition”
>
> *Link Technologies, Inc* -- Mikrotik & WISP Support Services
>
> *Office*: 314-735-0270  Website: http://www.linktechs.net
>
> Create Wireless Coverage’s with www.towercoverage.com
>
>
>
> *From:* Af <af-boun...@afmug.com> *On Behalf Of *Brough Turner
> *Sent:* Thursday, June 7, 2018 1:41 PM
> *To:* af@afmug.com
> *Subject:* [AFMUG] OSPF - How large can a flat network grow?
>
>
>
> We're an urban WISP with a dense mesh of wireless links and a router per
> building. I am concerned that, without paying attention, we have grown to
> 600+ routers and ~2550 routes in one OSPF domain. This network has a
> diverse mix of routers from CCR1036s down to RB750UPs. We're not having any
> OSPF problems at this time and I have plenty of other things to worry
> about, but I'd hate to hit some limit and have the whole thing blow up.
>
> Does anyone have experience (positive or negative) with large flat OSPF
> networks?
> And, if you have had problems, what were the problems?
>
> Thanks,
> Brough
>
> Brough Turner
> netBlazr Inc. – Free your Broadband!
> Mobile:  617-285-0433   Skype:  brough
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>
>
>

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