C
HAPTER
21
| Unicast Routing
Configuring the Open Shortest Path First Protocol (Version 2)
– 550 –
ES-4500G Series
■
You can further optimize the exchange of OSPF traffic by specifying
an area range that covers a large number of subnetwork addresses.
This is an important technique for limiting the amount of traffic
exchanged between Area Border Routers (ABRs).
■
And finally, you must specify a virtual link to any OSPF area that is
not physically attached to the OSPF backbone. Virtual links can also
be used to provide a redundant link between contiguous areas to
prevent areas from being partitioned, or to merge backbone areas.
(Note that virtual links are not supported for stubs or NSSAs.)
D
EFINING
N
ETWORK
A
REAS
B
ASED
ON
A
DDRESSES
OSPF protocol broadcast messages (i.e., Link State Advertisements or
LSAs) are restricted by area to limit their impact on network performance.
A large network should be split up into separate OSPF areas to increase
network stability, and to reduce protocol traffic by summarizing routing
information into more compact messages. Each router in an area shares
the same view of the network topology, including area links, route
summaries for directly connected areas, and external links to other areas.
Use the Routing Protocol > OSPF > Network Area (Add) page to define an
OSPF area and the interfaces that operate within this area. An autonomous
system must be configured with a backbone area, designated by the area
identifier 0.0.0.0. By default, all other areas are created as normal transit
areas.
Routers in a normal area may import or export routing information about
individual nodes. To reduce the amount of routing traffic flooded onto the
network, an area can be configured to export a single summarized route
that covers a broad range of network addresses within the area
(
). To further reduce the amount of routes passed between areas,
an area can be configured as a stub (
) or a not-so-
stubby area (
).
Normal Area
– A large OSPF domain should be broken up into several areas
to increase network stability and reduce the amount of routing traffic
required through the use of route summaries that aggregate a range of
addresses into a single route. The backbone or any normal area can pass
traffic between other areas, and are therefore known as transit areas. Each
router in an area has identical routing tables. These tables may include
area links, summarized links, or external links that depict the topology of
the autonomous system.
Figure 353: OSPF Areas
backbone
area
ABR
area
ABR
Содержание iPECS ES-4526G
Страница 1: ...USER GUIDE User Manual ES 4550G ES 4526G Managed Layer 3 Stackable GE Switch ...
Страница 38: ...CONTENTS 38 ES 4500G Series ...
Страница 58: ...SECTION I Getting Started 58 ES 4500G Series ...
Страница 70: ...CHAPTER 1 Introduction System Defaults 70 ES 4500G Series ...
Страница 84: ...CHAPTER 2 Initial Switch Configuration Managing System Files 84 ES 4500G Series Success Console ...
Страница 86: ...SECTION I Web Configuration 86 ES 4500G Series Multicast Filtering on page 413 ...
Страница 196: ...CHAPTER 6 VLAN Configuration Configuring MAC based VLANs 196 ES 4500G Series ...
Страница 204: ...CHAPTER 7 Address Table Settings Clearing the Dynamic Address Table 204 ES 4500G Series ...
Страница 228: ...CHAPTER 8 Spanning Tree Algorithm Configuring Interface Settings for MSTP 228 ES 4500G Series ...
Страница 230: ...CHAPTER 9 Rate Limit Configuration 230 ES 4500G Series Figure 106 Configuring Rate Limits ...
Страница 260: ...CHAPTER 12 Quality of Service Attaching a Policy Map to a Port 260 ES 4500G Series ...
Страница 478: ...CHAPTER 17 IP Configuration Setting the Switch s IP Address IP Version 6 478 ES 4500G Series ...
Страница 528: ...CHAPTER 20 IP Services Forwarding UDP Service Requests 528 ES 4500G Series ...
Страница 584: ...CHAPTER 21 Unicast Routing Configuring the Open Shortest Path First Protocol Version 2 584 ES 4500G Series ...
Страница 614: ...CHAPTER 22 Multicast Routing Configuring PIMv6 for IPv6 614 ES 4500G Series ...
Страница 628: ...CHAPTER 23 Using the Command Line Interface CLI Command Groups 628 ES 4500G Series ...
Страница 702: ...CHAPTER 26 SNMP Commands 702 ES 4500G Series ...
Страница 710: ...CHAPTER 27 Remote Monitoring Commands 710 ES 4500G Series ...
Страница 868: ...CHAPTER 34 Port Mirroring Commands Local Port Mirroring Commands 868 ES 4500G Series ...
Страница 890: ...CHAPTER 37 Address Table Commands 890 ES 4500G Series ...
Страница 1066: ...CHAPTER 43 LLDP Commands 1066 ES 4500G Series ...
Страница 1076: ...CHAPTER 44 Domain Name Service Commands 1076 ES 4500G Series ...
Страница 1286: ...CHAPTER 49 Multicast Routing Commands PIM Multicast Routing 1286 ES 4500G Series ...
Страница 1288: ...SECTION I Appendices 1288 ES 4500G Series ...
Страница 1293: ...APPENDIX A Software Specifications Management Information Bases 1293 ES 4500G Series UDP MIB RFC 2013 ...
Страница 1294: ...APPENDIX A Software Specifications Management Information Bases 1294 ES 4500G Series ...
Страница 1327: ...ES 4526G ES 4550G E042011 ST R01 150200000149A ...
Страница 1328: ...APRIL 2011 ISSUE 1 0 ...