PlAwAnSaI
Administrator
Scalability in Large Networks
Operating one large, flat EIGRP network is not a scalable solution for to the following reasons:
[li]Large routing tables[/li]
[li]High memory requirements[/li]
[li]Large amount of routing traffic[/li][/list]
Factors that Influence EIGRP Scalability
[li]Amount of routing information exchanged between peers[/li]
[li]Number of routers[/li]
[li]Depth of topology - the number of hops that information must travel to reach all routers[/li]
[li]Number of alternate paths through the network[/li][/list]
Factors That Influence EIGRP Scalability
[li]Quantity of routing information exchanged between peers: without proper route summarization, this can be excessive.[/li]
[li]Number of routers that must be involved when a topology change occurs.[/li]
[li]Depth of topology: the number of hops that information must travel to reach all routers.[/li]
[li]Number of alternate paths through the network.[/li][/list]
EIGRP Stub
[li]The EIGRP Stub Routing feature
[/list]
[li]Improves network stability[/li]
[li]Reduces resource utilization and[/li]
[li]Simplifies remote router (spoke) configuration[/li][/list]
[/li]
[li]Stub routing is commonly used in hub-and-spoke topology[/li]
[li]Stub router sends a special peer information packet to all neighboring routers to report its status as a stub router[/li]
[li]Any neighbor that receives a packet informing it of the stub status does not query the stub router for any routes[/li]
Router ที่ Configure ว่าเป็น Stub นั้น มันจะบอก Neighbor ของมันว่า ไม่ต้องส่ง Query มาถามแล้ว ตอนต้นบอกไปแค่ไหนมีแค่นั้น ไม่ต้องมารอ ดังนั้น Router ที่เป็น Neighbor จะไม่ส่ง Query Package ที่ไม่จำเป็นออกไป
Stub Review
[li]If Router B loses its connection to 10.1.8.0/24, it must build and transmit four queries: one query to each remote, and one query to Router A[/li]
[li]Each of the remote sites will also build a query towards Router A[/li]
[li]Router A receives four queries which it must process and answer[/li][/list]
It is typically undesirable for traffic from a distribution router to use a remote router as a transit path. A typical connection from a distribution router to a remote router would have much less bandwidth than a connection at the network core. Attempting to use a remote router with a limited bandwidth connection as a transit path would generally produce excessive congestion to the remote router. The EIGRP Stub Routing feature can prevent this problem by preventing the remote router from advertising core routes back to distribution routers. Routes learned by the remote router from distribution router 1 will not be advertised to distribution router 2. Since the remote router will not advertise core routes to distribution router 2, the distribution router will not use the remote router as a transit for traffic destined for the network core.
Credit: Cisco
Code:
http://www.thaiadmin.org/board/index.php?topic=71191
What Does the EIGRP DUAL-3-SIA Error Message Mean?
Introduction
Enhanced Interior Gateway Routing Protocol (EIGRP) is an enhanced distance-vector protocol based on the diffusing update algorithm (DUAL). It is capable of (conservatively) finding all loop-free paths to any given destination based on route advertisements from neighbors. The neighbor (or neighbors) with the best path to a destination is called the successor. The remaining neighbors with loop-free paths to the destination are called feasible successors. To reduce traffic load on the network, EIGRP maintains neighbor relationships and exchanges routing information only as needed, using a query process to find alternate paths when all loop-free paths to a destination have failed.
Code:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008010f016.shtml
Operating one large, flat EIGRP network is not a scalable solution for to the following reasons:
[li]Large routing tables[/li]
[li]High memory requirements[/li]
[li]Large amount of routing traffic[/li][/list]
Factors that Influence EIGRP Scalability
[li]Amount of routing information exchanged between peers[/li]
[li]Number of routers[/li]
[li]Depth of topology - the number of hops that information must travel to reach all routers[/li]
[li]Number of alternate paths through the network[/li][/list]
Factors That Influence EIGRP Scalability
[li]Quantity of routing information exchanged between peers: without proper route summarization, this can be excessive.[/li]
[li]Number of routers that must be involved when a topology change occurs.[/li]
[li]Depth of topology: the number of hops that information must travel to reach all routers.[/li]
[li]Number of alternate paths through the network.[/li][/list]
EIGRP Stub
[li]The EIGRP Stub Routing feature
[/list]
[li]Improves network stability[/li]
[li]Reduces resource utilization and[/li]
[li]Simplifies remote router (spoke) configuration[/li][/list]
[/li]
[li]Stub routing is commonly used in hub-and-spoke topology[/li]
[li]Stub router sends a special peer information packet to all neighboring routers to report its status as a stub router[/li]
[li]Any neighbor that receives a packet informing it of the stub status does not query the stub router for any routes[/li]
Router ที่ Configure ว่าเป็น Stub นั้น มันจะบอก Neighbor ของมันว่า ไม่ต้องส่ง Query มาถามแล้ว ตอนต้นบอกไปแค่ไหนมีแค่นั้น ไม่ต้องมารอ ดังนั้น Router ที่เป็น Neighbor จะไม่ส่ง Query Package ที่ไม่จำเป็นออกไป
Stub Review
[li]If Router B loses its connection to 10.1.8.0/24, it must build and transmit four queries: one query to each remote, and one query to Router A[/li]
[li]Each of the remote sites will also build a query towards Router A[/li]
[li]Router A receives four queries which it must process and answer[/li][/list]
It is typically undesirable for traffic from a distribution router to use a remote router as a transit path. A typical connection from a distribution router to a remote router would have much less bandwidth than a connection at the network core. Attempting to use a remote router with a limited bandwidth connection as a transit path would generally produce excessive congestion to the remote router. The EIGRP Stub Routing feature can prevent this problem by preventing the remote router from advertising core routes back to distribution routers. Routes learned by the remote router from distribution router 1 will not be advertised to distribution router 2. Since the remote router will not advertise core routes to distribution router 2, the distribution router will not use the remote router as a transit for traffic destined for the network core.
Credit: Cisco
Code:
http://www.thaiadmin.org/board/index.php?topic=71191
What Does the EIGRP DUAL-3-SIA Error Message Mean?
Introduction
Enhanced Interior Gateway Routing Protocol (EIGRP) is an enhanced distance-vector protocol based on the diffusing update algorithm (DUAL). It is capable of (conservatively) finding all loop-free paths to any given destination based on route advertisements from neighbors. The neighbor (or neighbors) with the best path to a destination is called the successor. The remaining neighbors with loop-free paths to the destination are called feasible successors. To reduce traffic load on the network, EIGRP maintains neighbor relationships and exchanges routing information only as needed, using a query process to find alternate paths when all loop-free paths to a destination have failed.
Code:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008010f016.shtml