Users Guide

Conguring ACL Logging.......................................................................................................................................... 137
Flow-Based Monitoring Support for ACLs.......................................................................................................................138
Behavior of Flow-Based Monitoring..........................................................................................................................138
Enabling Flow-Based Monitoring...............................................................................................................................139
9 Bidirectional Forwarding Detection (BFD).................................................................... 141
How BFD Works.............................................................................................................................................................. 141
BFD Packet Format.................................................................................................................................................. 142
BFD Sessions............................................................................................................................................................143
BFD Three-Way Handshake...................................................................................................................................... 144
Session State Changes............................................................................................................................................. 146
Important Points to Remember.......................................................................................................................................146
Congure BFD................................................................................................................................................................ 146
Congure BFD for Physical Ports..............................................................................................................................147
Congure BFD for Static Routes.............................................................................................................................. 150
Congure BFD for OSPF........................................................................................................................................... 151
Congure BFD for OSPFv3.......................................................................................................................................153
Congure BFD for IS-IS............................................................................................................................................ 155
Congure BFD for BGP.............................................................................................................................................157
Congure BFD for VRRP.......................................................................................................................................... 163
Conguring Protocol Liveness.................................................................................................................................. 166
Troubleshooting BFD.................................................................................................................................................166
10 Border Gateway Protocol IPv4 (BGPv4).................................................................... 168
Autonomous Systems (AS).............................................................................................................................................168
Sessions and Peers......................................................................................................................................................... 170
Establish a Session....................................................................................................................................................170
Route Reectors..............................................................................................................................................................171
BGP Attributes................................................................................................................................................................172
Best Path Selection Criteria...................................................................................................................................... 172
Weight.......................................................................................................................................................................174
Local Preference....................................................................................................................................................... 174
Multi-Exit Discriminators (MEDs)..............................................................................................................................175
Origin........................................................................................................................................................................ 176
AS Path.....................................................................................................................................................................176
Next Hop...................................................................................................................................................................177
Multiprotocol BGP...........................................................................................................................................................177
Implement BGP with Dell Networking OS....................................................................................................................... 178
Additional Path (Add-Path) Support..........................................................................................................................178
Advertise IGP Cost as MED for Redistributed Routes...............................................................................................178
Ignore Router-ID for Some Best-Path Calculations................................................................................................... 179
Four-Byte AS Numbers.............................................................................................................................................179
AS4 Number Representation.....................................................................................................................................179
AS Number Migration................................................................................................................................................ 181
BGP4 Management Information Base (MIB).............................................................................................................182
Important Points to Remember.................................................................................................................................182
7