Users Guide

Troubleshooting BFD............................................................................................................................................... 162
9 Border Gateway Protocol IPv4 (BGPv4)....................................................................................................164
Autonomous Systems (AS)...........................................................................................................................................164
Sessions and Peers........................................................................................................................................................ 166
Establish a Session...................................................................................................................................................166
Route Reflectors.............................................................................................................................................................167
BGP Attributes............................................................................................................................................................... 168
Best Path Selection Criteria....................................................................................................................................169
Weight........................................................................................................................................................................170
Local Preference...................................................................................................................................................... 170
Multi-Exit Discriminators (MEDs)........................................................................................................................... 171
Origin..........................................................................................................................................................................172
AS Path......................................................................................................................................................................173
Next Hop................................................................................................................................................................... 173
Multiprotocol BGP..........................................................................................................................................................173
Implement BGP with Dell Networking OS...................................................................................................................174
Additional Path (Add-Path) Support..................................................................................................................... 174
Advertise IGP Cost as MED for Redistributed Routes........................................................................................ 174
Ignore Router-ID in Best-Path Calculation............................................................................................................175
Four-Byte AS Numbers........................................................................................................................................... 175
AS4 Number Representation..................................................................................................................................175
AS Number Migration...............................................................................................................................................177
BGP4 Management Information Base (MIB)........................................................................................................178
Important Points to Remember..............................................................................................................................178
Configuration Information............................................................................................................................................. 179
BGP Configuration......................................................................................................................................................... 179
Enabling BGP............................................................................................................................................................ 180
Configuring AS4 Number Representations...........................................................................................................183
Configuring Peer Groups.........................................................................................................................................185
Configuring BGP Fast Fall-Over.............................................................................................................................187
Configuring Passive Peering................................................................................................................................... 189
Maintaining Existing AS Numbers During an AS Migration.................................................................................189
Allowing an AS Number to Appear in its Own AS Path.......................................................................................190
Enabling Graceful Restart........................................................................................................................................ 191
Enabling Neighbor Graceful Restart...................................................................................................................... 192
Filtering on an AS-Path Attribute...........................................................................................................................192
Regular Expressions as Filters................................................................................................................................ 194
Redistributing Routes.............................................................................................................................................. 195
Enabling Additional Paths........................................................................................................................................196
Configuring IP Community Lists.............................................................................................................................196
Configuring an IP Extended Community List........................................................................................................197
Filtering Routes with Community Lists..................................................................................................................198
Manipulating the COMMUNITY Attribute.............................................................................................................199
Changing MED Attributes...................................................................................................................................... 200
Changing the LOCAL_PREFERENCE Attribute................................................................................................. 200
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