GRE Tunnels in a Hub-Spoke Topology w/ EIGRP (Lab) #1

Our company DasBoot Corp. has opened a few offices in Turkey.
The corporate offices are in sunny Izmir and there is one branch in Istanbul, and two in Ankara.

They all have basic Internet connectivity to our trusted ISP: DynamiteBBS. Which by the way is running IS-IS in its backbone with MPLS on top.

As the Network engineer of DasBoot, we decide to create tunnels in a hub-spoke fashion, connecting our branches to the corporate network. We use private addressing in our network (eg. 172.16.0.0). Here's a demonstration of running EIGRP to facilitate full connectivity between our networks. I know not too complicated but good practice and extensible lab anyways. Enjoy..
(Download GNS3 Project files)

EIGRP Study Notes

Features:
Advanced Distance Vector routing protocol.
DUAL Algorithm
Neighbor relations
Sends only incremantal updates
Unequal-Cost Load Sharing

Packet Types:
Hello
Update
Query
Reply
Ack

Neighborship Requirements:
Receive Hello from neighbor
AS Number must match
K values must match

Simplified Metric

            10^7            total delay
256 * ( ------------   +      in tens     ) 
        Min.BW(Kbit)      of microseconds

3 Tables
Neighbor
Topology
Routing

Feasibility condition :
For a route to be considered feasible successor, the FD > AD.

Commands
ip hello-interval eigrp as-number seconds
ip hold-time eigrp autonomous-system-number seconds
bandwidth
ip bandwidth-percent eigrp as-number percent
variance
eigrp stub { receive-only | connected | summary | static }
ip summary-address as-number address mask

EIGRP Stub Router

Stub routers in EIGRP will only send limited information to their ONLY neighbor, a core (EIGRP) router.
This way the router will minimize memory and processor utilization.
Also helps speeding up convergence because a stub router answers to queries as inaccessible, thus limiting the query range and preventing SIA situations.

Syntax:
eigrp stub [receive-only | connected | redistributed | static | summary]