status, even if nothing is plugged into the interface. Line protocol "up"
means that the interface is able to send itself a frame and receive it back.
you'll find the line settings for the interface. An MTU, bandwidth, delay,
reliability, and load are listed. These values are used to calculate a distance-
vector protocol route metric.
when troubleshooting Ethernet problems. If the encapsulation type is not compat-
ible with other machines on the network, you will have communication problems.
Let's look at an example.
the machines on the network do not understand ARPA, they do not respond
to the broadcast. On the other hand, if a machine broadcast uses a SNAP
frame (#2), the router is designed to understand any incoming frame encapsu-
lation and can respond to the broadcast. Another bit of useful information
that the router adds to the ARP table is the encapsulation type of that machine.
Then, the next time that the router wants to speak with the given machine, it
uses the documented frame type instead of the type configured on the inter-
face. Here's a look at the ARP table (notice that the Type field is SNAP):