Cisco Administrative Distance

In: CCNP|Routing

19 Aug 2012

In Cisco IOS, Administrative Distance (AD) is used to determine the reliability of a routing protocol.

AD is a value between 0 and 255 and a lower value is preferred. The value 255 is considered as untrusted and a route with this value will not be placed into the routing table.

Route Source Default Distance Values
Connected interface 0
Static route 1
EIGRP summary 5
External BGP 20
Internal EIGRP 90
IGRP 100
OSPF 110
IS-IS 115
RIP 120
Exterior Gateway Protocol (EGP) 140
On-Demand routing (ODR) 160
External EIGRP 170
Internal BGP 200
Unknown 255

R1#show ip route
Codes: L - local, 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, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is 192.168.128.1 to network 0.0.0.0

S*    0.0.0.0/0 [1/0] via 192.168.128.1
      10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        10.1.0.0/16 is directly connected, Vlan5
L        10.1.0.250/32 is directly connected, Vlan5
O     192.168.4.0/23 [110/2] via 192.168.128.252, 1w3d, Vlan128

Static route, AD = 1 :

R1#show ip route 0.0.0.0
Routing entry for 0.0.0.0/0, supernet
  Known via "static", distance 1, metric 0, candidate default path
  Routing Descriptor Blocks:
  * 192.168.128.1
      Route metric is 0, traffic share count is 1

Connected interface, AD = 0 :

R1#show ip route 10.1.0.0
Routing entry for 10.1.0.0/16
  Known via "connected", distance 0, metric 0 (connected, via interface)
  Routing Descriptor Blocks:
  * directly connected, via Vlan5
      Route metric is 0, traffic share count is 1

OSPF route, AD = 110 :

R1#show ip route 192.168.4.0
Routing entry for 192.168.4.0/23, supernet
  Known via "ospf 1", distance 110, metric 2, type intra area
  Last update from 192.168.128.252 on Vlan128, 1w3d ago
  Routing Descriptor Blocks:
  * 192.168.128.252, from 192.168.128.252, 1w3d ago, via Vlan128
      Route metric is 2, traffic share count is 1

Comment Form

About this blog

Study notes of a swiss network engineer currently in the CCNP certification track

Categories

Calendar

August 2012
M T W T F S S
    Sep »
 12345
6789101112
13141516171819
20212223242526
2728293031  

Archives

If you like travel pictures