Figure 8: Sample Arp Process 1 Through 3; Figure 9: Sample Arp Process 4 And 5 - Juniper IGP - CONFIGURATION GUIDE V11.1.X Configuration Manual

Figure 8: Sample ARP Process 1 through 3

4.
5.

Figure 9: Sample ARP Process 4 and 5

ARP forces all receiving hosts to compare their IP addresses with the IP address of
the ARP request. So if host 1 sends another IP packet to host 2, host 1 searches its
ARP table for the router 1 MAC address.
If the default router/gateway becomes unavailable, then all the routing/packet
forwarding to remote destinations ceases. Usually, manual intervention is required
to restore connectivity, even though alternative paths may be available. Alternatively,
Virtual Router Redundancy Protocol (VRRP) may be used to prevent loss of
connectivity. See JUNOSe IP Services Configuration Guide.
arp
Host 1 transmits the IP packet to layer 3 DA (host 2) using router 1's MAC address.
Router 1 forwards IP packet to host 2. Router 1 might send an ARP request to
identify the MAC of host 2. (See Figure 9 on page 19.)
Chapter 1: Configuring IP
Address Resolution Protocol
19