Administrator Guide

Origin............................................................................................................................................................................. 165
AS Path......................................................................................................................................................................... 166
Next Hop.......................................................................................................................................................................166
Multiprotocol BGP............................................................................................................................................................. 166
Implement BGP ................................................................................................................................................................. 167
Advertise IGP Cost as MED for Redistributed Routes............................................................................................167
Ignore Router-ID for Some Best-Path Calculations.................................................................................................167
Four-Byte AS Numbers............................................................................................................................................... 167
AS4 Number Representation......................................................................................................................................168
AS Number Migration..................................................................................................................................................169
BGP4 Management Information Base (MIB)........................................................................................................... 170
Important Points to Remember...................................................................................................................................171
Configuration Information..................................................................................................................................................171
BGP Configuration............................................................................................................................................................. 172
Enabling BGP................................................................................................................................................................ 172
Configuring AS4 Number Representations...............................................................................................................175
Configuring Peer Groups.............................................................................................................................................176
Configuring BGP Fast Fail-Over.................................................................................................................................178
Configuring Passive Peering.......................................................................................................................................180
Maintaining Existing AS Numbers During an AS Migration.................................................................................... 180
Allowing an AS Number to Appear in its Own AS Path........................................................................................... 181
Filtering on an AS-Path Attribute...............................................................................................................................182
Regular Expressions as Filters.................................................................................................................................... 183
Redistributing Routes.................................................................................................................................................. 184
Enabling Additional Paths............................................................................................................................................184
Configuring IP Community Lists.................................................................................................................................185
Configuring an IP Extended Community List............................................................................................................186
Filtering Routes with Community Lists..................................................................................................................... 186
Manipulating the COMMUNITY Attribute.................................................................................................................187
Changing MED Attributes...........................................................................................................................................188
Changing the LOCAL_PREFERENCE Attribute......................................................................................................188
Configuring the local System or a Different System to be the Next Hop for BGP-Learned Routes................189
Changing the WEIGHT Attribute............................................................................................................................... 189
Enabling Multipath....................................................................................................................................................... 190
Filtering BGP Routes................................................................................................................................................... 190
Filtering BGP Routes Using Route Maps...................................................................................................................191
Filtering BGP Routes Using AS-PATH Information................................................................................................. 192
Configuring BGP Route Reflectors............................................................................................................................192
Aggregating Routes..................................................................................................................................................... 193
Configuring BGP Confederations...............................................................................................................................193
Enabling Route Flap Dampening.................................................................................................................................193
Changing BGP Timers................................................................................................................................................. 195
Setting the extended timer.........................................................................................................................................196
Enabling BGP Neighbor Soft-Reconfiguration.........................................................................................................196
Enabling or disabling BGP neighbors......................................................................................................................... 197
Route Map Continue....................................................................................................................................................198
Enabling MBGP Configurations........................................................................................................................................199
Configure IPv6 NH Automatically for IPv6 Prefix Advertised over IPv4 Neighbor.............................................199
BGP Regular Expression Optimization........................................................................................................................... 200
Debugging BGP.................................................................................................................................................................200
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