Users Guide

BGP Attributes...................................................................................................................................................................153
Best Path Selection Criteria........................................................................................................................................153
Weight........................................................................................................................................................................... 155
Local Preference..........................................................................................................................................................155
Multi-Exit Discriminators (MEDs).............................................................................................................................. 156
Origin..............................................................................................................................................................................157
AS Path..........................................................................................................................................................................157
Next Hop.......................................................................................................................................................................158
Multiprotocol BGP............................................................................................................................................................. 158
Implement BGP with Dell Networking OS...................................................................................................................... 158
Advertise IGP Cost as MED for Redistributed Routes............................................................................................159
Ignore Router-ID in Best-Path Calculation............................................................................................................... 159
Four-Byte AS Numbers...............................................................................................................................................159
AS4 Number Representation......................................................................................................................................160
AS Number Migration...................................................................................................................................................161
BGP4 Management Information Base (MIB)........................................................................................................... 162
Important Points to Remember..................................................................................................................................163
Configuration Information.................................................................................................................................................163
BGP Configuration.............................................................................................................................................................164
Enabling BGP................................................................................................................................................................164
Configuring AS4 Number Representations...............................................................................................................167
Configuring Peer Groups.............................................................................................................................................168
Configuring BGP Fast Fall-Over..................................................................................................................................171
Configuring Passive Peering....................................................................................................................................... 172
Maintaining Existing AS Numbers During an AS Migration.....................................................................................173
Allowing an AS Number to Appear in its Own AS Path...........................................................................................173
Enabling Graceful Restart........................................................................................................................................... 174
Enabling Neighbor Graceful Restart.......................................................................................................................... 175
Filtering on an AS-Path Attribute...............................................................................................................................175
Regular Expressions as Filters.................................................................................................................................... 176
Redistributing Routes.................................................................................................................................................. 178
Enabling Additional Paths............................................................................................................................................ 178
Configuring IP Community Lists.................................................................................................................................178
Configuring an IP Extended Community List............................................................................................................179
Filtering Routes with Community Lists..................................................................................................................... 180
Manipulating the COMMUNITY Attribute................................................................................................................. 181
Changing MED Attributes...........................................................................................................................................182
Changing the LOCAL_PREFERENCE Attribute......................................................................................................182
Changing the NEXT_HOP Attribute......................................................................................................................... 183
Changing the WEIGHT Attribute............................................................................................................................... 183
Enabling Multipath....................................................................................................................................................... 183
Filtering BGP Routes................................................................................................................................................... 184
Filtering BGP Routes Using Route Maps..................................................................................................................185
Filtering BGP Routes Using AS-PATH Information................................................................................................. 185
Configuring BGP Route Reflectors............................................................................................................................186
Aggregating Routes..................................................................................................................................................... 186
Configuring BGP Confederations...............................................................................................................................187
Enabling Route Flap Dampening.................................................................................................................................187
Changing BGP Timers................................................................................................................................................. 189
Enabling BGP Neighbor Soft-Reconfiguration.........................................................................................................190
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