Static Routing

Downsides of Directly Connected Networks

When a router only has its interfaces configured, and the routing table contains the directly connected networks but no other routes, only devices on those directly connected networks are reachable. (Hosts aren’t able to ping each other)

What network commonly uses a static route?

Stub network

Define: Stub network

A network accessed by a single route

Command to add static route (Cisco)

ip route [network] [subnet mask] [next-hop address]

Ex: ip route 172.16.1.0 255.255.255.0 172.16.2.2

Define: Summary Route

A single route that can be used to represent multiple routes.

Benefits of a route summarization/aggregation

Has the same exit interface or next-hop IP address = Smaller routing tables

More efficient routing table lookup process

Define: Default Route

A static route that is used when there are no routes that have a specific match to the destination network

When are default routes used?

They are used by stub routers

Default route command

ip route 0.0.0.0 0.0.0.0 [ip address:interface]

What are 4 things that Ethernet interfaces do since they participate in a LAN?

Have Layer 2 MAC address.

Are recorded in a device’s ARP Cache.

Issue ARP Requests when needed.

Issue ARP Replies when required.

Conditions for a serial interface to be in the up state

Only after the other end of the serial link has also been properly configured and activated

• Must be on the same network/subnet

• Clock rate

Pros and Cons of: debug all command

Pros:

• Useful when configuring or troubleshooting a network.

Cons

• Can disrupt router operations.

• Intensive use of CPU and memory resources.

• Run as few debug processes as necessary.

• Disable them immediately when they are no longer needed.