show ip route displays a Cisco IOS router’s routing table—the database of known destinations and forwarding instructions. An unconfigured router cannot forward packets because its table is empty. section 9.2.1 section 9.4
Read the output by recognizing these common entries:
- C marks a connected route to a network attached to an up/up interface. section 9.4
- L marks a local host route to the interface’s exact IP address, using a /32 prefix. section 9.4
- Gateway of last resort is not set means the router has no default route. section 9.2.1
- The router selects the most specific matching route, meaning the route with the longest prefix length. section 9.4
Two interfaces create four routes
After configuring and enabling G0/0 as 192.168.1.1/24 and G0/1 as 192.168.2.1/24, show ip route displays connected routes for 192.168.1.0/24 and 192.168.2.0/24, plus local /32 routes for both interface addresses. section 9.2.1
R1# show ip route #1
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP #2
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area #2
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 #2
E1 - OSPF external type 1, E2 - OSPF external type 2 #2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 #2
ia - IS-IS inter area, * - candidate default, U - per-user static route #2
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP #2
a - application route #2
+ - replicated route, % - next hop override, p - overrides from PfR #2
Gateway of last resort is not set #3
#1 Views R1’s routing table
#2 Various codes identifying different route types
#3 R1 doesn’t have a default route.
Browse representative output showing route-code definitions and the gateway-of-last-resort status. section 9.2.1
