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I'm a beginner in networking stuff and just wondered if Static Routing has any use in large networks ? How about small ones ?

In which cases we prefer to use static over dynamic routing ? I searched for this one and the most reason i saw people mentioned was resource usage problem with dynamic routing .

Thanks

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    Define "large network"? You'll find static routes in configurations everywhere. The entire network, however, will most likely not be strung together out of statics -- because it would be an manageable mess. – Ricky Beam Mar 23 at 20:28
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There are corner cases where static routing may be used in large networks, but static routing doesn't scale, so large networks will be run with dynamic routing. It would be a difficult to impossible task to maintain a large network using static routing, and the odds are a simple misconfiguration could cause big problems. Most modern business routers have no resource problems with dynamic routing protocols.

Small networks are fine to use static routing. A network with a single router doesn't even need to configure any static routes because a router will inherently know about the directly connected networks.

  • So can we say static routing almost has no use in these days networks ? – Stick Mar 23 at 0:21
  • I wouldn't say no use, but it is pretty rare in medium or large networks. It is a lot of work to build and properly maintain it on a large scale. Dynamic routing is generally pretty easy to configure, and it it can automatically adapt to changes. – Ron Maupin Mar 23 at 0:25
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    As an example, I still sometimes see "floating static routes" for usage cost backup links (pay per time used or amount of traffic) at remote sites. Often this is a static default route that is given a high cost that will only be used if the dynamic routes are lost for some reason (i.e. the main link or links fail). – YLearn Mar 23 at 1:06
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I work at a large ISP and before at a different large ISP and both networks extensively use static routing. Mostly on the firewalls as they don’t want to run an IGP or BGP on the firewalls, but you can also find static routes on routers and even on end hosts.

  • The implementation of OSPF on firewalls often was very buggy (and perhaps often still is) which is why companies tend to prefer static routing on firewalls. These inplementations are often also quite basic, lacking many of the features you find on the routers.
  • An end host with multiple interfaces (e.g. production and management) might need static routes to steer outbound traffic over the correct interface. I’ve also seen RIP being used for this, running between the end hosts and their first-hop routers.
  • For static routes on routers, an example can be pointing towards the firewalls, as they can’t receive any routes from them. There are also corner cases but I can’t come up with any right now.

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