Dell S4820T Configuration Manual page 183

The bold line shows that IS-IS BFD sessions are enabled.
R2(conf-router_isis)#bfd all-neighbors
R2(conf-router_isis)#do show bfd neighbors
* - Active session role
Ad Dn - Admin Down
C - CLI
I - ISIS
O - OSPF
R - Static Route (RTM)
LocalAddr RemoteAddr Interface State Rx-int Tx-int Mult Clients
* 2.2.2.2 2.2.2.1
Changing IS-IS Session Parameters
BFD sessions are configured with default intervals and a default role.
The parameters that you can configure are: Desired TX Interval, Required Min RX Interval, Detection
Multiplier, and system role. These parameters are configured for all IS-IS sessions or all IS-IS sessions out
of an interface. If you change a parameter globally, the change affects all IS-IS neighbors sessions. If you
change a parameter at the interface level, the change affects all IS-IS sessions on that interface.
To change parameters for all IS-IS sessions or for IS-IS sessions on a single interface, use the following
commands.
To view session parameters, use the show bfd neighbors detail command, as shown in Verifying
BFD Sessions with BGP Neighbors Using the show bfd neighbors Command in
BGP Information.
• Change parameters for all IS-IS sessions.
ROUTER-ISIS mode
bfd all-neighbors interval milliseconds min_rx milliseconds multiplier value
role [active | passive]
• Change parameters for IS-IS sessions on a single interface.
INTERFACE mode
isis bfd all-neighbors interval milliseconds min_rx milliseconds multiplier
value role [active | passive]
Disabling BFD for IS-IS
If you disable BFD globally, all sessions are torn down and sessions on the remote system are placed in a
Down state.
If you disable BFD on an interface, sessions on the interface are torn down and sessions on the remote
system are placed in a Down state. Disabling BFD does not trigger a change in BFD clients; a final Admin
Down packet is sent before the session is terminated.
To disable BFD sessions, use the following commands.
• Disable BFD sessions with all IS-IS neighbors.
ROUTER-ISIS mode
no bfd all-neighbors
• Disable BFD sessions with IS-IS neighbors on a single interface.
Bidirectional Forwarding Detection (BFD)
Te 2/1 Up 100 100 3 I
Displaying BFD for
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