Users Guide

9 Border Gateway Protocol IPv4 (BGPv4)....................................................................................................163
Autonomous Systems (AS)...........................................................................................................................................163
Sessions and Peers........................................................................................................................................................ 165
Establish a Session...................................................................................................................................................165
Route Reflectors............................................................................................................................................................ 166
BGP Attributes................................................................................................................................................................167
Best Path Selection Criteria....................................................................................................................................168
Weight....................................................................................................................................................................... 169
Local Preference...................................................................................................................................................... 169
Multi-Exit Discriminators (MEDs).......................................................................................................................... 170
Origin...........................................................................................................................................................................171
AS Path......................................................................................................................................................................172
Next Hop................................................................................................................................................................... 172
Multiprotocol BGP..........................................................................................................................................................172
Implement BGP with Dell Networking OS...................................................................................................................173
Additional Path (Add-Path) Support..................................................................................................................... 173
Advertise IGP Cost as MED for Redistributed Routes........................................................................................ 173
Ignore Router-ID in Best-Path Calculation............................................................................................................174
Four-Byte AS Numbers........................................................................................................................................... 174
AS4 Number Representation.................................................................................................................................. 174
AS Number Migration.............................................................................................................................................. 176
BGP4 Management Information Base (MIB)........................................................................................................177
Important Points to Remember.............................................................................................................................. 177
Configuration Information............................................................................................................................................. 178
BGP Configuration......................................................................................................................................................... 178
Enabling BGP............................................................................................................................................................ 179
Configuring AS4 Number Representations...........................................................................................................182
Configuring Peer Groups.........................................................................................................................................184
Configuring BGP Fast Fall-Over.............................................................................................................................186
Configuring Passive Peering................................................................................................................................... 188
Maintaining Existing AS Numbers During an AS Migration.................................................................................188
Allowing an AS Number to Appear in its Own AS Path.......................................................................................189
Enabling Graceful Restart....................................................................................................................................... 190
Enabling Neighbor Graceful Restart.......................................................................................................................191
Filtering on an AS-Path Attribute........................................................................................................................... 191
Regular Expressions as Filters................................................................................................................................ 193
Redistributing Routes.............................................................................................................................................. 194
Enabling Additional Paths........................................................................................................................................195
Configuring IP Community Lists.............................................................................................................................195
Configuring an IP Extended Community List........................................................................................................196
Filtering Routes with Community Lists..................................................................................................................197
Manipulating the COMMUNITY Attribute.............................................................................................................198
Changing MED Attributes.......................................................................................................................................199
Changing the LOCAL_PREFERENCE Attribute..................................................................................................199
Configuring the local System or a Different System to be the Next Hop for BGP-Learned Routes...........200
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