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I have a small network with 10 VLANs, mostly routed via our core layer 3 switch. RIP is enabled on the core switch, but I'm in the process of adding a second router for a couple of VLANs as our core switch doesn't support policy based routing.

In a previous question, i asked for help configuring a Linux box as a second router, which is now mostly working, but I'm seeing some odd results whereby sometimes it works, and at other times it doesn't. The default gateway coupled with one static route on two servers should be all I need for everything to work on our network, but it appears as though something is interfering, as tcpdump shows that packets aren't always going to the correct gateway that I've configured.

Not understanding routing protocols, i was wondering if they could be what appears to be interfering with what I'm doing?

For info, 3 VLANs are routed exclusively via the Linux router, 6 exclusively by the core switch, and 1 VLAN is routed by both.

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2 Answers 2

up vote 4 down vote accepted

Routing Protocols would be utilized to send/receive routes with other routing devices. If the VLANs are not changing on a regular basis then you will likely not need to use them. You would be better off setting persistent (static) routes on your two routing devices.

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The rule I use is this... if a device (host or router) has more than one path out, and different routers could be the lowest-cost next-hop at any point, then you need a dynamic routing protocol.

In short, if there is ever a link-failure condition that destroys static routing, you need dynamic routing.

Corner cases exist where you can get by with advanced static routing (Cisco href), but if you are asking the question, I will assume advanced static routing is not something you would try to maintain.

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