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 > netBlazr Inc. <http://www.netblazr.com/> | Google+ > <https://plus.google.com/102447512447094746687/posts?hl=en> | Twitter > <https://twitter.com/#%21/brough> | LinkedIn > <http://www.linkedin.com/in/broughturner> | Facebook > <http://www.facebook.com/brough.turner> | Blog > <http://blogs.broughturner.com/> | Personal website > <http://broughturner.com/> > > >
