is much easier using EIGRP.
possible. This is only a recommended solution that meets the requirements placed on the
network architect.
to the remote sites without spending more money on interfaces, CSUs/DSUs, and so on can be
met by using the Multilink PPP protocol. This protocol binds the ISDN 64 k link to the Frame
Relay 64 k link and creates a virtual link of 128 k. You can do this starting with 11.2 Cisco IOS
using the virtual template interface. This is another reason to use IP unnumbered because if the
ISDN link has an IP address as well as a Frame Relay interface, that would not work.
interfaces are actually used to handle traffic. All of the virtual access interfaces are made from
the same virtual template via copying. Therefore, if you specify an IP address on the virtual
template, your router might have problems because multiple interfaces will have the same IP
address when your router has multiple virtual access interfaces. That is why you should use ip
unnumbered on your virtual template.