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In this video we're going to discuss static routes.

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I've been asked a number of times about static routes.

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Are you able for example to have multiple static routes configured on a router? Are you able to have multiple

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default routes configured on a router?

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Can you mix default routes and static routes? What's the effect of all of the above?

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In this example, we're gonna configure static routes on router 1 and test connectivity to the loopback

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of router 5. We have router 2, router 3, and router 4 in the typology and they configured with

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different subnets. Router 2 is configured with IP address 10.1.1.2 on the interface, router 3 is configured

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with 10.1.2.2 on this interface and router 4 is configured as 10.1.3.2 on this interface or link.

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So here's router 1,

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What we're gonna test

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Is connectivity to the loopback of router 5.

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So from router 1, is it able to ping the loopback of router five?

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So at the moment when I ping the loopback out of router 5 we get timeouts.

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The router is not able to ping the loopback of router 5. Show IP route shows us the routing table.

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What you'll notice is that it only contains connected and local routes, there's no route to 5.5.5.5

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de-bug IP packet

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as an example will show us what happens when the router tries to ping that address. So I'm going to ping

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5.5.

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5.5.

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and repeat it once and let's see what the output looks like.

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Notice unroutable the router doesn't know where to route the packets.

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And again that's because there's no route to the destination.

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There's also no gateway of last resort set on the router

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So it has no way to get to this IP address.

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We could configure a route as follows.

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So an exact match on the route and point it to 10.1.1.2 which is router 2. Show IP

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route now shows us that route in the routing table.

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So can this router ping the loopback of router 5?

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And the answer is yes it can.

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I'm going to disable IP domain look-up here to speed up traceroute.

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So let's trace to the loopback of router 5.

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Notice it's going via 10.1.1.2 which is router 2 and then it gets to router 5.

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What happens if I configure a static route like this and pointed it to router 3? Which way will

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the traffic go?

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So let's have a look at the routing table.

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Show IP route shows us two entries in the routing table.

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There are two ways to get to the loopback of router 5.

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So if I trace to that loopback notice it's still going via router 2.

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In other words it's going to 10.1.1.1

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and the reason for that is because this entry is more specific than this entry. Routers when deciding

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where to route traffic

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look at the longest match of a route. This route is a 32-bit match

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this is a 24-bit match.

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So the traffic's gonna go via 10.1.1.2

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and we can prove that by doing a traceroute if we remove this route from the routing table

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and then do a trace again notice the traceroute is going via 10.1.1.2 but that's because we only have

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this route in the routing table.

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If we created another static route like this

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via router 4

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which way will the traffic go? So show IP route shows us the two entries we've got a /16

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/24.

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So when we trace to router 5 notice it's going via router 3 because this is a longer match.

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That is a longer match than this.

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So router 3 is preferred rather than router 4.

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But again if we removed

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that route from the routing table so I'm gonna remove this entry.

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So remove the static route

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now when we look at the routing table we only have this entry so traffic will go via 10.1.3.2.

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In other words it's going to go via router 4.

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If I add a more specific product of let's say /24

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going via router 3 agian

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notice the traffic goes via router 3

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And if I use a more specific route such as this

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going via router 2 rather

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notice the traffic goes via router 2. Show IP route shows us those routes /28 route is

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more specific than a /24 route which is more specific than a /16 route.

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So remember with static routes and this applies to other routing protocols as well more specific matches

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win.

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So what happens if we add a route like this?

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Same mask as router 2 configure it to go to router 3.

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So show IP route,

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notice the difference in the routing table now we've got two entries for the same route.

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So when we trace to the loopback now notice its doing load balancing traffic is load balancing across

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both parts and that's because we've got two equal entries in the routing table.

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So show run pipe include route

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these two routes are going to be used for load balancing because they're the most specific and they're 

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the same length.

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These two will be ignored

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but if we copy that and add an entry

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going to 10.1.3.2 for router 4 the routing table shows us three entries

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now. If we trace to the loopback

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now notice its going to load balance across those three routes.

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You need to be careful with this because sometimes depending on the router the load balancing may actually

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not be true but for CCNA level we assume that it load balances as follows.

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So show run pipe include route things to remember more specific entries win if there are multiple

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entries with the same route and same mask such as these three the routable load balance across those

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paths equally.

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So in other words equal-cost load balancing or load sharing. Hope you enjoyed this video if it was of benefit

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to you please like it and please subscribe to my YouTube channel.

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I wish you all the very best.