Rockwell ArmorStratix 5700 series, Instructions Manual

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332 Rockwell Automation Publication 1783-UM007F-EN-P - September 2016
Chapter 7 Configure Switch Features
Enhanced Interior Gateway
Routing Protocol (EIGRP) EIGRP is available on Stratix 8300switches and Stratix 5400 and 5410
switches with Layer 3 firmware.
EIGRP is a Cisco proprietary, distance-vector-routing protocol. Key
capabilities that distinguish EIGRP from other routing protocols include fast
convergence, support for variable-length subnet mask, support for partial
updates, and support for multiple network layer protocols.
A router that runs EIGRP stores all neighbor routing tables so that it can
quickly adapt to alternate routes. If no appropriate route exists, EIGRP queries
its neighbors to discover an alternate route. These queries propagate until an
alternate route is found. Its support for variable-length subnet masks permits
routes to be automatically summarized on a network number boundary. In
addition, EIGRP can be configured to summarize on any bit boundary at any
interface. EIGRP does not make periodic updates. Instead, it sends partial
updates only when the metric for a route changes. Propagation of partial
updates is automatically bounded so that only those routers that need the
information are updated.
Neighbor discovery is the process that the EIGRP router uses to learn
dynamically of other routers on directly attached networks. EIGRP routers
send out multicast hello packets to announce their presence on the network.
You can also define static neighbors, which receive unicast packets. When the
router receives a hello packet from a new neighbor, it sends its topology table
to the neighbor with an initialization bit set. When the neighbor receives the
topology update with the initialization bit set, the neighbor sends its topology
table back to the EIGRP router. Once this neighbor relationship is established,
routing updates are not exchanged unless there is a change in the network
topology.
EIGRP uses the Diffusing Update Algorithm (DUAL), which provides
loop-free operation at every instance throughout a route computation. DUAL
allows all devices that are involved in a topology change to synchronize
simultaneously. Routers that are not affected by topology changes are not
involved in recomputations.
To configure EIGRP, create an EIGRP instance and associate networks.
EIGRP sends updates to the interfaces in the specified networks. If you do not
specify an interface network, it is not advertised in any EIGRP update.