Enhanced Interior Gateway Protocol (EIGRP) is a Cisco
proprietary distance vector routing protocol.   It is based on
the Diffusing Update Algorithm (DUAL), which is a method of
finding loop-free paths through a network.   Directly
connected routers running EIGRP form neighbor adjacencies in
order to propagate best-path and alternate-path routing
information for configured and learned routes.

The tables defined within the MIB are closely aligned with how
the router command-line interface for EIGRP displays
information on EIGRP configurations, i.e., the topology table
contains objects associated with the EIGRP topology commands,
and the peer table contains objects associated withe EIGRP
neighbor commands, etc.

There are five main tables within this mib:

   EIGRP VPN table
      Contains information regarding which virtual private
      networks (VPN) are configured with EIGRP.

   EIGRP traffic statistics table
      Contains counter & statistcs regarding specific types of
      EIGRP packets sent and related collective information
      per VPN and per autonomous system (AS).

   EIGRP topology table
      Contains information regarding EIGRP routes received in
      updates and originated locally.   EIGRP sends and
      receives routing updates from adjacent routers running
      EIGRP with which it formed a peer relationship.

   EIGRP peer (neighbor) table
      Contains information about neighbor EIGRP routers with
      which peer adjacencies have been established.   EIGRP
      uses a Hello protocol to form neighbor relationships
      with directly connected routers also running EIGRP.

   EIGRP interfaces table
      Contains information and statistics on each of the 
      configured to run.

RIB-scale 
========== 
The Wide-Metrics feature calculates all metrics in 64-bit 
under named mode EIGRP. Since the RIB can only hold 32-bit, 
we divide the wide metrics by RIB-scale (range 1-255, 
default value 128) to convert it to a 32-bit value 
before assiging it to RIB metrics.