Service Manual

Implementation Information......................................................................................................................................111
Conguration Task List for Prex Lists....................................................................................................................111
ACL Resequencing..........................................................................................................................................................114
Resequencing an ACL or Prex List....................................................................................................................... 115
Route Maps......................................................................................................................................................................116
Implementation Information..................................................................................................................................... 116
Flow-Based Monitoring Support for ACLs...................................................................................................................116
Behavior of Flow-Based Monitoring........................................................................................................................117
Enabling Flow-Based Monitoring.............................................................................................................................118
7 Bidirectional Forwarding Detection (BFD).................................................................................................. 120
How BFD Works............................................................................................................................................................. 120
BFD Packet Format.................................................................................................................................................. 121
BFD Sessions............................................................................................................................................................ 122
BFD Three-Way Handshake.................................................................................................................................... 123
Session State Changes............................................................................................................................................125
Important Points to Remember.................................................................................................................................... 125
Congure BFD................................................................................................................................................................ 125
Congure BFD for Physical Ports...........................................................................................................................126
Congure BFD for Static Routes............................................................................................................................129
Congure BFD for OSPF..........................................................................................................................................131
Congure BFD for OSPFv3.....................................................................................................................................133
Congure BFD for IS-IS...........................................................................................................................................135
Congure BFD for BGP........................................................................................................................................... 137
Congure BFD for VRRP.........................................................................................................................................144
Conguring Protocol Liveness................................................................................................................................ 146
Troubleshooting BFD................................................................................................................................................146
8 Border Gateway Protocol IPv4 (BGPv4).....................................................................................................148
Autonomous Systems (AS)........................................................................................................................................... 148
Sessions and Peers........................................................................................................................................................ 150
Establish a Session...................................................................................................................................................150
Route Reectors..............................................................................................................................................................151
BGP Attributes................................................................................................................................................................152
Best Path Selection Criteria....................................................................................................................................152
Weight........................................................................................................................................................................154
Local Preference.......................................................................................................................................................154
Multi-Exit Discriminators (MEDs).......................................................................................................................... 155
Origin..........................................................................................................................................................................156
AS Path......................................................................................................................................................................156
Next Hop................................................................................................................................................................... 157
Multiprotocol BGP.......................................................................................................................................................... 157
Implement BGP with Dell Networking OS...................................................................................................................158
Additional Path (Add-Path) Support......................................................................................................................158
Advertise IGP Cost as MED for Redistributed Routes........................................................................................ 158
Ignore Router-ID in Best-Path Calculation............................................................................................................ 159
Four-Byte AS Numbers........................................................................................................................................... 159
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