What is the purpose of the eigrp stub configuration command?
A.
to increase scalability by limiting the EIGRP query range
B.
to reduce the size of the routing table by blocking the D EX (External EIGRP) routes into the
EIGRP stub router
C.
to reduce the convergence time by enabling the EIGRP stub router to propagate the EIGRP
queries from the EIGRP hub router
D.
to reduce the convergence time by enabling the EIGRP stub router to also perform query
requests to the EIGRP hub router
Explanation:
Complex, redundant EIGRP networks can cause scalability problems. The best solution to this is
to provide a means within the context of the EIGRP protocol itself to control traffic flows and limit
query depth. The EIGRP Stub Router functionality in Cisco IOS Software Release 12.0(7)T can
achieve this solution.
The Enhanced Interior Gateway Routing Protocol (EIGRP) Stub Routing feature improves network
stability, reduces resource utilization, and simplifies stub router configuration.
Stub routing is commonly used in a hub and spoke network topology. In a hub and spoke network,
one or more end (stub) networks are connected to a remote router (the spoke) that is connected to
one or more distribution routers (the hub). The remote router is adjacent only to one or moredistribution routers. The only route for IP traffic to follow into the remote router is through a
distribution router. This type of configuration is commonly used in WAN topologies where the
distribution router is directly connected to a WAN. The distribution router can be connected to
many more remote routers. Often, the distribution router will be connected to 100 or more remote
routers. In a hub and spoke topology, the remote router must forward all non local traffic to a
distribution router, so it becomes unnecessary for the remote router to hold a complete routing
table. Generally, the distribution router need not send anything more than a default route to the
remote router.
When using the EIGRP Stub Routing feature, you need to configure the distribution and remote
routers to use EIGRP, and to configure only the remote router as a stub. Only specified routes are
propagated from the remote (stub) router. The router responds to queries for summaries,
connected routes, redistributed static routes, external routes, and internal routes with the message
“inaccessible.” A router that is configured as a stub will send a special peer information packet to
all neighboring routers to report its status as a stub router.
Any neighbor that receives a packet informing it of the stub status will not query the stub router for
any routes, and a router that has a stub peer will not query that peer. The stub router will depend
on the distribution router to send the proper updates to all peers.
Reference:
http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a0080087
026.html