Service Manual

9 Bidirectional Forwarding Detection (BFD)....................................................................136
How BFD Works............................................................................................................................................................. 136
BFD Packet Format...................................................................................................................................................137
BFD Sessions............................................................................................................................................................138
BFD Three-Way Handshake...................................................................................................................................... 139
Session State Changes..............................................................................................................................................141
Important Points to Remember........................................................................................................................................141
Congure BFD................................................................................................................................................................. 141
Congure BFD for Physical Ports..............................................................................................................................142
Congure BFD for Static Routes...............................................................................................................................145
Congure BFD for OSPF.......................................................................................................................................... 146
Congure BFD for OSPFv3.......................................................................................................................................149
Congure BFD for IS-IS............................................................................................................................................ 150
Congure BFD for BGP............................................................................................................................................ 152
Congure BFD for VRRP.......................................................................................................................................... 159
Conguring Protocol Liveness................................................................................................................................... 161
Troubleshooting BFD................................................................................................................................................. 161
10 Border Gateway Protocol IPv4 (BGPv4).....................................................................163
Autonomous Systems (AS).............................................................................................................................................163
Sessions and Peers.........................................................................................................................................................165
Establish a Session................................................................................................................................................... 165
Route Reectors.............................................................................................................................................................166
BGP Attributes................................................................................................................................................................167
Best Path Selection Criteria...................................................................................................................................... 167
Weight...................................................................................................................................................................... 169
Local Preference.......................................................................................................................................................169
Multi-Exit Discriminators (MEDs)..............................................................................................................................170
Origin.........................................................................................................................................................................171
AS Path..................................................................................................................................................................... 171
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 for Some Best-Path Calculations....................................................................................................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
Conguration Information................................................................................................................................................178
BGP Conguration.......................................................................................................................................................... 178
Enabling BGP............................................................................................................................................................179
Conguring AS4 Number Representations................................................................................................................182
7