The Router#show ip route command displays the routing table, containing all known networks and subnetworks, and a code indicating how the route was learned. Some of the codes are:

C Connected, S Static, I IGRP, R RIP, M Mobile, B BGP

D EIGRP, EX EIGRP External, O OSPF, IA OSPF inter area

N1 OSPF NSSA external type 1, N2 OSPF NSSA external type 2

E1 OSPF external type 1, E2 OSPF external type 2, E EGP

i IS-IS, L1 IS-IS level-1, L2 IS-IS level-2, ia IS-IS inter area

* - candidate default, U per-user static route, O ODR

 

 

Additional commands are:

Router#show ip route {connected | network | rip | igrp | static }

 

The routing table maps prefixes to an outbound interface. We know this as the network address, and the subnet mask, enabling an address to match a bit pattern, and be sent out on an interface. Entries in the routing table, from routing protocols, will generally have the next hop router to tell the router where to send the packets.

 

A Show ip route command will output the following:

R <IP addr> [120/1] via <next hop ip addr>, <time>, <interface>

 

Meaning of these are:

R Routing Protocol

<IP addr> is the destination IP Address or Network Address, and will normally have the Subnet number of bits.

[120/1] is the Administrative Distance / and the Metric. Eg RIP Administrative Distance = 120 and this example would mean the destination was one hop away. (RIP metric is hops).

<next hop ip addr> is the interface at the next hop.

<time> is the number of seconds since the last Routing update. This counts up if the Show ip route is entered again.

<interface> is the interface of the router the command is entered on.

 

Administrative Distances are as follows:

Connected 0

Static 1

EIGRP summary route 5

eBGP 20

EIGRP 90

IGRP 100

OSPF 110

RIP 120

EIGRP(external) 170

iBGP (external) 200

Unknown 255