Hi everybody
Please consider the static routes below:
R1#show ip route
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is 200.200.200.3 to network 0.0.0.0
C 200.200.200.0/24 is directly connected, FastEthernet0/0
C 199.199.199.0/24 is directly connected, Vlan1
S* 0.0.0.0/0 [1/0] via 200.200.200.3
is directly connected, FastEthernet0/0
R1#show version
Cisco IOS Software, 2600 Software (C2691-ADVIPSERVICESK9-M), Version 12.4(15)T6, RELEASE SOFTWARE (fc2)
Technical Support:
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According to following link( I quoted below), in ios version 12.2 or later, static route configured with next hop has AD of 1 while static route configured with exit int has AD of 1°. AD of 1° is preferred to 1 . AD 1° lies between 0 to 1.
Since R1 has ios 12.4 therefore R1 should prefer static route configured using exit int over static route configured using next hop. But if you look at the routing table above, R1 has installed both routes i.e static route configured with next hop and static route configured with exit int.
Based on the following link, R1 should have installed static route configured with exit int only because its Ad of 1° is better than AD of 1 of static route configured with next hop.
I will appreciate your input.
thanks.
http://en.wikipedia.org/wiki/Administrative_distance
The following table gives the default administrative distances used by Cisco routers.
| Protocol | Administrative distance |
|---|
| Directly connected route | 0 |
| Static route out an interface | 1° |
| Static route to next-hop address | 1 |
| EIGRP summary route | 5 |
| External BGP | 20 |
| Internal EIGRP | 90 |
| IGRP | 100 |
| OSPF | 110 |
| IS-IS | 115 |
| RIP | 120 |
| EGP | 140 |
| ODR | 160 |
| External EIGRP | 170 |
| Internal BGP | 200 |
| DHCP-learned | 254 |
| Unknown | 255 |
Notes:
- An administrative distance of 255 will cause the router to disbelieve the route entirely and not use it.
- Since IOS 12.2, the administrative distance of a static route with an exit interface is 1. Prior to the release of 12.2 it was in fact 0.
° Actual administrative distance is recognized somewhere between 0 and 1. This AD is more trustworthy than 1 but less trustworthy than 0.
