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| 1.2 |  | Key Characteristics of Scalable Internetworks |
| 1.2.5 |  | Making the network adaptable |

An adaptable network will handle the addition and coexistence of multiple routed and routing protocols. EIGRP is an exceptionally adaptable protocol because it supports routing information for three routed protocols:

- IP
- IPX
- AppleTalk

The IOS also supports route redistribution, which is described in Module 8. Route redistribution allows routing information to be shared among two or more different routing protocols. For example, RIP routes could be redistributed, or injected, into an OSPF area.

Mixing routable and non-routable protocols
A network delivering both routable and non-routable traffic has some unique problems. Routable protocols, such as IP, can be forwarded from one network to another based on a network layer address. Non-routable protocols, such as SNA, do not contain a network layer address and cannot be forwarded by routers. Most non-routable protocols also lack a mechanism to provide flow control and are sensitive to delays in delivery. Any delays in delivery causing packets to arrive out of order can result in the session being dropped. An adaptable network must accommodate both routable and non-routable protocols.

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