Users Guide

9 Border Gateway Protocol IPv4 (BGPv4)..........................................................................................................161
Autonomous Systems (AS)....................................................................................................................................161
Sessions and Peers................................................................................................................................................. 163
Establish a Session............................................................................................................................................164
Route Reflectors.....................................................................................................................................................164
BGP Attributes......................................................................................................................................................... 165
Best Path Selection Criteria............................................................................................................................166
Weight.................................................................................................................................................................168
Local Preference...............................................................................................................................................168
Multi-Exit Discriminators (MEDs)...................................................................................................................168
Origin...................................................................................................................................................................169
AS Path................................................................................................................................................................ 170
Next Hop.............................................................................................................................................................170
Multiprotocol BGP..................................................................................................................................................170
Implement BGP with Dell Networking OS.........................................................................................................171
Additional Path (Add-Path) Support.............................................................................................................. 171
Advertise IGP Cost as MED for Redistributed Routes................................................................................171
Ignore Router-ID in Best-Path Calculation.................................................................................................172
Four-Byte AS Numbers....................................................................................................................................172
AS4 Number Representation..........................................................................................................................172
AS Number Migration.......................................................................................................................................174
BGP4 Management Information Base (MIB)............................................................................................... 176
Important Points to Remember.....................................................................................................................176
Configuration Information....................................................................................................................................177
BGP Configuration..................................................................................................................................................177
Enabling BGP..................................................................................................................................................... 178
Configuring AS4 Number Representations................................................................................................. 181
Configuring Peer Groups................................................................................................................................182
Configuring BGP Fast Fall-Over.................................................................................................................... 185
Configuring Passive Peering...........................................................................................................................186
Maintaining Existing AS Numbers During an AS Migration...................................................................... 187
Allowing an AS Number to Appear in its Own AS Path............................................................................ 188
Enabling Graceful Restart............................................................................................................................... 189
Enabling Neighbor Graceful Restart.............................................................................................................190
Filtering on an AS-Path Attribute.................................................................................................................. 190
Regular Expressions as Filters.........................................................................................................................191
Redistributing Routes.......................................................................................................................................193
Enabling Additional Paths............................................................................................................................... 193
Configuring IP Community Lists................................................................................................................... 194
Configuring an IP Extended Community List............................................................................................. 195
Filtering Routes with Community Lists........................................................................................................ 196
Manipulating the COMMUNITY Attribute....................................................................................................196
Changing MED Attributes............................................................................................................................... 198
Changing the LOCAL_PREFERENCE Attribute...........................................................................................198
Configuring the local System or a Different System to be the Next Hop for BGP-Learned
Routes................................................................................................................................................................. 199
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