Administrator Guide

Creating a Route Map..............................................................................................................................................128
Congure Route Map Filters...................................................................................................................................130
Conguring Match Routes......................................................................................................................................130
Conguring Set Conditions..................................................................................................................................... 132
Congure a Route Map for Route Redistribution.................................................................................................133
Congure a Route Map for Route Tagging............................................................................................................133
Continue Clause........................................................................................................................................................134
8 Bidirectional Forwarding Detection (BFD).................................................................................................. 135
How BFD Works............................................................................................................................................................. 135
BFD Packet Format........................................................................................................................................................136
BFD Sessions...................................................................................................................................................................137
BFD Three-Way Handshake.......................................................................................................................................... 138
Session State Changes..................................................................................................................................................140
Important Points to Remember.............................................................................................................................. 140
Congure BFD................................................................................................................................................................ 140
Congure BFD for Physical Ports........................................................................................................................... 141
Congure BFD for Static Routes............................................................................................................................142
Congure BFD for OSPF.........................................................................................................................................145
Congure BFD for OSPFv3.....................................................................................................................................149
Congure BFD for IS-IS...........................................................................................................................................152
Congure BFD for BGP...........................................................................................................................................155
Conguring Protocol Liveness.................................................................................................................................161
Troubleshooting BFD.......................................................................................................................................................161
9 Border Gateway Protocol IPv4 (BGPv4).................................................................................................... 163
Autonomous Systems (AS)........................................................................................................................................... 164
Sessions and Peers........................................................................................................................................................ 166
Establish a Session...................................................................................................................................................166
Route Reectors.............................................................................................................................................................167
Communities................................................................................................................................................................... 168
BGP Attributes................................................................................................................................................................168
Best Path Selection Criteria....................................................................................................................................168
Weight..............................................................................................................................................................................170
Local Preference.............................................................................................................................................................170
Multi-Exit Discriminators (MEDs)............................................................................................................................171
Origin................................................................................................................................................................................172
AS Path............................................................................................................................................................................ 172
Next Hop......................................................................................................................................................................... 173
Multiprotocol BGP.......................................................................................................................................................... 173
Implement BGP with Dell Networking OS...................................................................................................................173
Additional Path (Add-Path) Support...................................................................................................................... 173
Advertise IGP Cost as MED for Redistributed Routes.........................................................................................174
Ignore Router-ID for Some Best-Path Calculations..............................................................................................174
Four-Byte AS Numbers............................................................................................................................................174
AS4 Number Representation.................................................................................................................................. 175
Contents
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