The Level 3 Router needs to be able to associate IP addresses to MAC addresses, this is done with an ARP table

The Router ARP Table

Layer 3

E8-08-88-CB-3F-B4

44-AB-5F-DF-C1-FB

00-1B-63-B4-45-C6

0F-99-3E-A6-2F-01

170.170.10.10

170.170.10.11

170.170.10.12

170.170.10.13

EF-0E-82-C2-34-44

4E-AC-5A-D2-C1-2B

0D-1D-6D-B2-42-46

0C-9A-AE-36-5F-A1

170.170.11.10

170.170.11.11

170.170.11.12

170.170.11.13