Network Protocol Code

 

A ROUTING PROTOCOL CODE IS A ONE- OR TWO-CHARACTER CODE THAT IS USED TO IDENTIFY THE ROUTING PROTOCOL THAT WAS USED TO LEARN A ROUTE. THE ROUTING PROTOCOL CODE IS DISPLAYED IN THE ROUTING TABLE OF A ROUTER.

THE FOLLOWING IS A LIST OF COMMON ROUTING PROTOCOL CODES:

C: CONNECTED ROUTE. THIS ROUTE IS FOR A NETWORK THAT IS DIRECTLY CONNECTED TO THE ROUTER.

S: STATIC ROUTE. THIS ROUTE IS MANUALLY CONFIGURED ON THE ROUTER.

I: IGRP ROUTE. THIS ROUTE IS LEARNED USING THE INTERIOR GATEWAY ROUTING PROTOCOL (IGRP).

R: RIP ROUTE. THIS ROUTE IS LEARNED USING THE ROUTING INFORMATION PROTOCOL (RIP).

B: BGP ROUTE. THIS ROUTE IS LEARNED USING THE BORDER GATEWAY PROTOCOL (BGP).

D: EIGRP-INTERNAL ROUTE. THIS ROUTE IS LEARNED USING THE ENHANCED INTERIOR GATEWAY ROUTING PROTOCOL (EIGRP) AND IS FOR A NETWORK THAT IS WITHIN THE SAME AUTONOMOUS SYSTEM (AS).

EX: EIGRP-EXTERNAL ROUTE. THIS ROUTE IS LEARNED USING EIGRP AND IS FOR A NETWORK THAT IS IN A DIFFERENT AS.

O: OSPF ROUTE. THIS ROUTE IS LEARNED USING THE OPEN SHORTEST PATH FIRST (OSPF) ROUTING PROTOCOL.

THE ROUTING PROTOCOL CODE IS A VALUABLE TOOL FOR TROUBLESHOOTING ROUTING PROBLEMS. BY KNOWING THE ROUTING PROTOCOL CODE, YOU CAN QUICKLY DETERMINE HOW A ROUTE WAS LEARNED AND WHICH ROUTING PROTOCOL IS RESPONSIBLE FOR ROUTING TRAFFIC TO THAT NETWORK.

HERE IS AN EXAMPLE OF A ROUTING TABLE WITH ROUTING PROTOCOL CODES:

Destination | Next Hop | Prefix | Metric | Type
------- | -------- | ----- | ------- | ----
192.168.1.0 | 192.168.1.1 | 255.255.255.0 | 0 | C
10.0.0.0 | 192.168.1.1 | 255.0.0.0 | 10 | S
172.16.0.0 | 192.168.1.1 | 255.255.0.0 | 15 | I

IN THIS EXAMPLE, THE ROUTE TO 192.168.1.0 IS A CONNECTED ROUTE (C), THE ROUTE TO 10.0.0.0 IS A STATIC ROUTE (S), AND THE ROUTE TO 172.16.0.0 IS AN IGRP ROUTE (I).

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