IRDP Protocol –
ICMP Router Discovery Protocol (IRDP) is First Hop Redundancy Protocol (FHRP) for hosts to discover the presence and location of routers on their IPv4 [p2p type=”slug” value=”what-is-local-area-network”]LAN[/p2p] network. The IRDP is defined by the IETF RFC 1256 standard.
IRDP eliminates the need to manually configure routing information.[p2p type=”slug” value=”internet-control-message-protocol-icmp”]ICMP[/p2p] protocol is leveraged in IRDP.
Below is a scenario where IRDP is configured across 2 Routers and depicts the failover across the IRDP enabled Routers –
Now , R2 will be configured with IRDP configuration on Interface Fa0/0. And given high preference of 100 to behave as default gateway for hosts.
The same way as R2 , R3 is also configured for irdp on interface Fa0/0 however as backup default Router by giving lower preference of 90.
Now that IRDP is complete, we will try to ping R4 Router Loopback IP of 22.214.171.124 and see IRDP normal scenario and failover function.
In Normal scenario traffic from Host R1 destined towards R4 Loopback (126.96.36.199) shall take path through IRDP router with higher prefernce and in this case its R2 (Preference 100)
Now we will shut interafce fa0/0 of R2
When the primary path is shut , traffic from R1 will take backup path via IRDP Router R3 with preference of 90 as shown below –
From this lab scenario, we understood how IRDP performs FHRP functionality and provides redundancy to endpoints.
To know more about IRDP protocol watch this video –