There are different metric structures and algorithms that protocol use to find the best path to send a packet or an information but that are not compatible with the other protocols. Multiple routing protocol exists on a single router to share an information about best route. This is very hard to find the best route using multiple protocols.
Administrative distance help to find the best path when there is two or more routing paths available using multiple protocols. Administrative distance is that feature that router use to select the best path. It maintains the reliability of the routing protocols.
Default Distance Value Table
Routing protocol /Route source
|
Default Distance Values
|
| Connected interface | 0 |
| Static route | 1 |
| Enhanced Interior Gateway Routing Protocol (EIGRP) summary route |
5 |
| External Border Gateway Protocol (eBGP) | 20 |
| Internal EIGRP | 90 |
| IGRP | 100 |
| OSPF | 110 |
| Intermediate System-to-Intermediate System (IS-IS) | 115 |
| Routing Information Protocol (RIP) | 120 |
| Exterior Gateway Protocol (EGP) | 140 |
| On Demand Routing (ODR) | 160 |
| External EIGRP | 170 |
| Internal BGP | 200 |
| Unknown | 255 |
Note :- If the Administrative Distance is 255 or above it then the router will not add any route in the routing table.
If you have configured redistribution on your router then you have to change your administrative distance on a router, redistribution is a procedure or a way which helps to communicate routers running on different protocols.
Suppose if you have configured RIP with 120 administrative distance and and IGRP configured with 100 administrative distance router. Now, if you want to give priority to RIP or if you want to send your route information via RIP then you need to change in your Administrative Distance value from the IGRP as by default it will take IGRP to find the best path because its administrative distance is less from RIP.
During configuration of routing protocols such as RIP, IGRP, EIGRP etc. we have to give administrative distance value.
Suppose if you have configured RIP with 120 administrative distance and and IGRP configured with 100 administrative distance router. Now, if you want to give priority to RIP or if you want to send your route information via RIP then you need to change in your Administrative Distance value from the IGRP as by default it will take IGRP to find the best path because its administrative distance is less from RIP.
During configuration of routing protocols such as RIP, IGRP, EIGRP etc. we have to give administrative distance value.
No comments:
Post a Comment