CST $240$ Routing Technologies

Lab $23$

OSPF $$ Singe Area

After you complete each step, put a $$ or $$x$$ in the completed box

Objectives

We will have $3$ routers so that we will have one path as the shortest path which would be connecting $2$ routers

$1.$ Setup the topology

Note: $2811$ router might be a good option.

$2.$ Now add in the addressing scheme to the topology $($we will configure the devices shortly$)$

$3.$ Configure both PCs

$4.$ Configure the routers $($use any addresses within the specified for the router interfaces & set the clock rates to $64000)$

$5.$ Once you configure address on every router port, your topology will look like the following

Now you should be able to ping the default gateway from say PC$1$

But you should not be able to ping router $1$ as shown below.

This ping failure is expected as we have not yet configured either RIP or OSPF protocol.

$6.$ Now go to R$0$ and we will configure it with the OSPF protocol

Recap on the commands

$$router ospf $1$ gets us into configuration with OSPF with $1$ being the process id

We then added in the networks and the wildcards with an area of zero

For more information on wildcards, go to the last page of the lab

Repeat the same process for R$1$ and R$2$

$7.$ Now let$$s check the configuration by pinging from PC$0$ to R$0,$ then R$1,$ then R$2$ and finally PC$1.$

OSPF protocol was successful!

$8.$ Now let$$s use Auto Play feature to check out the protocol in action.

You will see the packets go to R$0$ from PC$0$ and R$0$ will send the packets to both R$1$ and R$2$

R$0$ will updating its routing table as it doesn$$t know which is the shortest path.

$9.$ Now let$$s uncheck the all the other protocols

$10.$ Clear the simulation and Auto Play again

After the route table has been updated, it is taking the path which is shortest to it i$.$e$.$ from PC$0$ to R$0$ to R$2$ and then to PC$1$

Our OSPF configuration which is shortest path first is successful

Wildcard

$($Here is a little more information on wildcards. Wildcards will also be used in labs $18$ and $19$ Access Control Lists$)$

$$ Different from subnet mask. Subnet mask is used to separate the network portion and host portion in IP address.

$$ Used with network ID to filter the interfaces $($Reverse subnet mask$)$

$$ Used to match corresponding octet in network portion.

Tells OSPF the part of network address that must be matched.

Wildcard mask value of $0$ in an octet tells IOS to compare to see if the numbers match

Wildcard mask value of $255$ tells IOS to ignore that octet when comparing the numbers.

Wildcard $0\mathrm{.}0\mathrm{.}0\mathrm{.}0$: Compare all $4$ octets. In other words, the numbers must exactly match.

Wildcard $0\mathrm{.}0\mathrm{.}0\mathrm{.}255$: Compare the first $3$ octets only. Ignore the last octet when comparing the numbers.

Wildcard $0\mathrm{.}0\mathrm{.}255\mathrm{.}255$: Compare the first $2$ octets only. Ignore the last $2$ octets when comparing the numbers.

Wildcard $0\mathrm{.}255\mathrm{.}255\mathrm{.}255$: Compare the first octet only. Ignore the last $3$ octets when comparing the numbers.

Wildcard $255\mathrm{.}255\mathrm{.}255\mathrm{.}255$: Compare nothing$$this wildcard mask means that all addresses will match the network command.