R2 is sited in a shared data center; make the serial link back into R1 as secure as possible at Layer 2.
Ensure traffic from VLAN4, including any attached router interfaces to VLAN4, is hidden behind R5 lo0 address when directed toward all external router networks.
A router is to be installed onto VLAN4 in the future. This router will have a default configuration, so allow R6 to assist dynamically to aid the configuration process. The router will require an IP address of 10.50.50.6 and should load a configuration file called R9-config from a fictitious TFTP server on 172.16.0.59.
