Information About BFD
BFD is a detection protocol designed to provide fast forwarding-path failure detection times for media types, encapsulations, topologies, and routing protocols. You can use BFD to detect forwarding path failures at a uniform rate, rather than the variable rates for different protocol hello mechanisms. BFD makes network profiling and planning easier and reconvergence time consistent and predictable.
BFD provides subsecond failure detection between two adjacent devices.
This section includes the following topics:
Asynchronous Mode
Cisco NX-OS supports the BFD asynchronous mode, which sends BFD control packets between two adjacent devices to activate and maintain BFD neighbor sessions between the devices. You configure BFD on both devices (or BFD neighbors). Once BFD has been enabled on the appropriate protocols, Cisco NX-OS creates a BFD session, negotiates BFD session parameters, and begins to send BFD control packets to each BFD neighbor at the negotiated interval. The BFD session parameters include the following:
-
Desired minimum transmit interval—The interval at which this device wants to send BFD hello messages.
-
Required minimum receive interval—The minimum interval at which this device can accept BFD hello messages from another BFD device.
-
Detect multiplier—The number of missing BFD hello messages from another BFD device before this local device detects a fault in the forwarding path.
BFD Detection of Failures
Once a BFD session has been established and timer negotiations are complete, BFD neighbors send BFD control packets that act in the same manner as an IGP hello protocol to detect liveliness, except at a more accelerated rate. BFD detects a failure, but the protocol must take action to bypass a failed peer.
BFD sends a failure detection notice to the BFD-enabled protocols when it detects a failure in the forwarding path. The local device can then initiate the protocol recalculation process and reduce the overall network convergence time.
When a failure occurs in the network, the following occurs:
1. The BFD neighbor session with the BFD neighbor router is torn down.
2. BFD notifies the local BFD process that the BFD neighbor is no longer reachable.
3. The local BFD process tears down the BFD neighbor relationship.
4. If an alternative path is available, the routers immediately start converging on it.
Note The BFD failure detection occurs in less than a second.
BFD Echo Function
The BFD echo function sends echo packets from the forwarding engine to the remote BFD neighbor. The BFD neighbor forwards the echo packet back along the same path in order to perform detection; the BFD neighbor does not participate in the actual forwarding of the echo packets. The echo function and the forwarding engine are responsible for the detection process. BFD can use the slow timer to slow down the asynchronous session when the echo function is enabled and reduce the number of BFD control packets that are sent between two BFD neighbors. Also, the forwarding engine tests the forwarding path on the remote (neighbor) system without involving the remote system, so there is less interpacket delay variability and faster failure detection times.
The echo function is asymmetrical when both BFD neighbors are running echo function.
Security
Cisco NX-OS uses the packet Time to Live (TTL) value to verify that the BFD packets came from an adjacent BFD peer. For all asynchronous and echo request packets, the BFD neighbor sets the TTL value to 255 and the local BFD process verifies the TTL value as 255 before processing the incoming packet. For the echo response packet, BFD sets the TTL value to 254.
Virtualization Support
BFD supports virtual routing and forwarding instances (VRFs).
Guidelines and Limitations
BFD has the following configuration guidelines and limitations:
-
BFD supports BFD version 1.
-
BFD supports IPv4, IPv6, OSPFv2, BGPv4 and static routes.
-
BFD supports single-hop BFD.
-
BFD for BGP supports single-hop eBGP and iBGP with an update source.
-
BFD supports the following Layer 3 interfaces—physical interfaces, port channels, subinterfaces, and VLAN interfaces (SVI).
-
BFD does not support authentication for BFD or per-link BFD sessions on a port channel.
-
BFD depends on a Layer 3 adjacency information to discover topology changes, including Layer 2 topology changes. A BFD session on a VLAN interface (SVI) may not be up after the convergence of the Layer 2 topology if there is no Layer 3 adjacency information available.
-
Port channel configuration limitations:
– For Layer 3 port channels used by BFD, you must enable the Link Aggregation Control Protocol (LACP) on the port channel.
– For Layer 2 port channels used by SVI sessions, you must enable LACP on the port channel.
– When you change the topology (for example, add or delete a link into a VLAN, delete a member from a Layer 2 port channel, and so on), the SVI session could be affected. It may go down first and then come up after the topology discovery is finished.
Tip If you do not want the SVI sessions to flap and you need to change the topology, you can disable the BFD feature before making the changes and reenable BFD after the changes have been made. You can also configure the BFD timer to be a large value (for example, 5 seconds), and change it back to a fast timer after the above events complete.
-
Cisco NX-OS does not distribute the BFD operation to compatible modules to offload the CPU for BFD packet processing.
-
BFD does not support stateless restarts and in-service software upgrades (ISSUs).
-
If you want to enable BFD for a peer reachable through a port channel, you must configure LACP on the port channel.
-
BFD echo mode and Unicast Reverse Path Forwarding (URPF) are mutually exclusive and cannot both be enabled on a BFD interface. If you want to configure an interface for BFD, you must disable either BFD echo mode or URPF.
-
HSRP for IPv6, VRRPv3 for IPv6 are not supported with BFD.
-
Static IPv6 routes are supported with BFD.
-
The BFD echo function is supported only when using global IPv6 addresses and not when using IPv6 link-local addresses.
Configuring BFD
This section includes the following topics:
Configuration Hierarchy
You can configure BFD at the global level, VRF level, at the interface or port channel level, or at the subinterface level (for physical interfaces and port channels). The VRF configuration overrides global configuration. The interface or port channel configuration overrides VRF or global configuration. On supported interfaces, the subinterface-level configuration overrides the interface or port channel configuration. See the “Configuring BFD on BGP” section for more information.
For physical ports that are members of a port channel, the member port inherits the master port channel BFD configuration. The member port subinterfaces can override the master port channel BFD configuration.
Enabling the BFD Feature
You must enable the BFD feature before you can configure BFD on an interface and protocol.
SUMMARY STEPS
1.
configure terminal
2.
feature bfd
3.
(Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
feature bfd
Example:
switch(config)# feature bfd
|
Enables the BFD feature.
|
Step 3
|
copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring Global BFD Parameters
You can configure the BFD session parameters for all BFD sessions on the device. The BFD session parameters are negotiated between the BFD peers in a three-way handshake.
See the “Configuring BFD on an Interface” section to override these global session parameters on an interface.
SUMMARY STEPS
1.
configure terminal
2.
bfd interval
mintx
min_rx
msec
multiplier
value
3.
bfd slow-timer
[
interval
]
4.
(Optional) show running-config bfd
5.
(Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
bfd interval
mintx
min_rx
msec
multiplier
value
Example:
switch(config)# bfd interval 250 min_rx 250 multiplier 3
|
Configures the BFD session parameters for all BFD sessions on the device. You can override these values by configuring the BFD session parameters on an interface. The
mintx
and
msec
range is from 250 to 999 milliseconds and the default is 250. The multiplier range is from 3 to 50. The multiplier default is 3.
To return to the default settings, use the no bfd interval command.
|
Step 3
|
bfd slow-timer
[
interval
]
Example:
switch(config)# bfd slow-timer 2000
|
Configures the slow timer. This value determines how fast BFD starts up a new session and is used to slow down the asynchrounous sessions when the BFD echo function is enabled. The range is from 1000 to 30000 milliseconds. The default is 2000.
To return to the default settings, use the no bfd slow-timer command.
|
Step 4
|
exit
Example:
switch(config)# exit
switch#
|
Returns to EXEC mode.
|
Step 5
|
show running-config bfd
Example:
switch# show running-config bfd
|
(Optional) Displays the BFD running configuration.
|
Step 6
|
copy running-config startup-config
Example:
switch# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD on an Interface
You can configure the BFD session parameters for all BFD sessions on an interface. The BFD session parameters are negotiated between the BFD peers in a three-way handshake.
This configuration overrides the global session parameters for the configured interface.
SUMMARY STEPS
1.
configure terminal
2.
interface
int-if
3.
bfd interval
mintx
min_rx
msec
multiplier
value
4.
(Optional) show running-config bfd
5.
(Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
interface
int-if
Example:
switch(config)# interface ethernet 1/2
switch(config-if)#
|
Enters interface configuration mode. Use the
?
keyword to display the supported interfaces.
|
Step 3
|
bfd interval
mintx
min_rx
msec
multiplier
value
Example:
switch(config-if)# bfd interval 250 min_rx 250 multiplier 3
|
Configures the BFD session parameters for all BFD sessions on the interface. This command overrides the global BFD session parameters. The
mintx
and
msec
range is from 250 to 999 milliseconds and the default is 250. The multiplier range is from 3 to 50. The multiplier default is 3.
To return to the default settings, use the no bfd interval command.
|
Step 4
|
exit
Example:
switch(config-if)# exit
switch (config)#
|
Exits interface configuration mode.
|
Step 5
|
exit
Example:
switch (config)# exit
switch#
|
Exits configuration mode and returns to EXEC mode.
|
Step 6
|
show running-config bfd
Example:
switch# show running-config bfd
|
(Optional) Displays the BFD running configuration.
|
Step 7
|
copy running-config startup-config
Example:
switch# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD on a Port Channel
You can configure the BFD session parameters for all BFD sessions on a port channel. For example, if the BFD session for one link on a port channel is up, BFD informs client protocols, such as BGP, that the port channel is up. The BFD session parameters are negotiated between the BFD peers in a three-way handshake.
This configuration overrides the global session parameters for the configured port channel. The member ports of the port channel inherit the port channel BFD session parameters, unless you configure subinterface-level BFD parameters on a member port. See the “Configuring BFD on BGP” section for more information.
SUMMARY STEPS
1.
configure terminal
2.
interface port-channel
number
3.
(Optional)
bfd interval
mintx
min_rx
msec
multiplier
value
4.
(Optional) show running-config bfd
5.
(Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
interface port-channel
number
Example:
switch(config)# interface port-channel 2
switch(config-if)#
|
Enters port channel configuration mode. Use the
?
keyword to display the supported number range.
|
Step 3
|
bfd interval
mintx
min_rx
msec
multiplier
value
Example:
switch(config-if)# bfd interval 250 min_rx 250 multiplier 3
|
(Optional) Configures the BFD session parameters for all BFD sessions on the port channel. This command overrides the global BFD session parameters. The
mintx
and
msec
range is from 250 to 999 milliseconds and the default is 250. The multiplier range is from 3 to 50. The multiplier default is 3.
To return to the default settings, use the no bfd interval command.
|
Step 4
|
exit
Example:
switch(config-if)# exit
switch (config)#
|
Exits interface configuration mode.
|
Step 5
|
exit
Example:
switch (config)# exit
switch#
|
Exits configuration mode, returns to EXEC mode.
|
Step 6
|
show running-config bfd
Example:
switch# show running-config bfd
|
(Optional) Displays the BFD running configuration.
|
Step 7
|
copy running-config startup-config
Example:
switch# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring the BFD Echo Function
You can configure the BFD echo function on one or both ends of a BFD-monitored link. The echo function slows down the required minimum receive interval, based on the configured slow timer. The RequiredMinEchoRx BFD session parameter is set to zero if the echo function is disabled. The slow timer becomes the required minimum receive interval if the echo function is enabled.
SUMMARY STEPS
1.
configure terminal
2.
bfd slow-timer
echo-interval
3.
interface
int-if
4.
bfd echo
5.
(Optional) show running-config bfd
6.
(Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
bfd slow-timer
echo-interval
Example:
switch(config)# bfd slow-timer 2000
|
Configures the slow timer used in the echo function. This value determines how fast BFD starts up a new session and is used to slow down the asynchrounous sessions when the BFD echo function is enabled. This value overwrites the required minimum receive interval when the echo function is enabled. The range is from 1000 to 30000 milliseconds. The default is 2000.
To return to the default settings, use the no bfd slow-timer command.
|
Step 3
|
interface
int-if
Example:
switch(config)# interface ethernet 1/2
switch(config-if)#
|
Enters interface configuration mode. Use the
?
keyword to display the supported interfaces.
|
Step 4
|
bfd echo
Example:
switch(config-if)# bfd echo
|
Enables the echo function. The default is enabled.
To disable the echo function, use the no bfd echo command.
|
Step 5
|
exit
Example:
switch(config-if)# exit
switch (config)#
|
Exits interface configuration mode.
|
Step 6
|
exit
Example:
switch (config)# exit
switch#
|
Exits configuration mode and returns to EXEC mode.
|
Step 7
|
show running-config bfd
Example:
switch# show running-config bfd
|
(Optional) Displays the BFD running configuration.
|
Step 8
|
copy running-config startup-config
Example:
switch# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD on BGP
You can configure BFD for the Border Gateway Protocol (BGP).
SUMMARY STEPS
1.
configure terminal
2.
router bgp
as-number
3.
neighbor
{
ip-address | ipv6-address
}
remote-as
as-number
4.
bfd
5.
(Optional) show running-config bgp
6.
(Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
router bgp
as-number
Example:
switch(config)# router bgp 64496
switch(config-router)#
|
Enables BGP and assigns the AS number to the local BGP speaker. The AS number can be a 16-bit integer or a 32-bit integer in the form of a higher 16-bit decimal number and a lower 16-bit decimal number in xx.xx format.
|
Step 3
|
neighbor
{
ip-address
|
ipv6-address
}
remote-as
as-number
Example:
switch(config-router)# neighbor
209.165.201.1
remote-as 64497
switch(config-router-neighbor)#
|
Configures the IPv4 or IPv6 address and AS number for a remote BGP peer. The
ip-address
format is x.x.x.x. The
ipv6-address
format is A:B::C:D.
|
Step 4
|
bfd
Example:
switch(config-router-neighbor)# bfd
|
Enables BFD for this BGP peer.
|
Step 5
|
show running-config bgp
Example:
switch(config-router-neighbor)# show running-config bgp
|
(Optional) Displays the BGP running configuration.
|
Step 6
|
copy running-config startup-config
Example:
switch(config-router-neighbor)# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD on PIM
You can configure BFD for the Protocol Independent Multicast (PIM) protocol.
BEFORE YOU BEGIN
Enable the BFD feature. See the “Enabling the BFD Feature” section.
Enable the PIM feature. See the Cisco Nexus 3000 Series NX-OS Multicast Routing Configuration Guide for more information.
SUMMARY STEPS
1. configure terminal
2. ip pim bfd
3. interface type slot/port
4. (Optional) ip pim bfd-instance [ disable ]
5. (Optional) show running-config pim
6. (Optional) copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
ip pim bfd
Example:
switch(config)# ip pim bfd
|
Enables BFD for PIM.
|
Step 3
|
interface type slot/port
Example:
switch(config)# interface ethernet 2/1
switch(config-if)#
|
Enters interface configuration mode. Use the ? keyword to display the supported interfaces.
|
Step 4
|
ip pim bfd-instance [ disable ]
Example:
switch(config-if)# ip pim bfd-instance
|
(Optional) Enables or disables BFD on a PIM interface. The default is disabled.
|
Step 5
|
show running-config pim
Example:
switch(config)# show running-config pim
|
(Optional) Displays the PIM running configuration.
|
Step 6
|
copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD on OSPFv2
You can configure BFD for the Open Shortest Path First Protocol (OSPFv2).
SUMMARY STEPS
1.
configure terminal
2.
router ospf
process-id
3.
bfd
4. (Optional)
show running-config ospf
5. (Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
router ospf
process-id
Example:
switch(config)# router ospf 64496
switch(config-router)#
|
Creates a new OSPFv2 process with a configured id.
|
Step 3
|
bfd
Example:
switch(config-router)# bfd
|
Enables BFD for this OSPFv2 peer. The default value is disabled
.
|
Step 4
|
interface int-if
Example:
switch(config-router)# interface ethernet 1/2
switch (config-if)#
|
Enters interface configuration mode. Use the
?
keyword to display the supported interfaces.
|
Step 5
|
[no] ip ospf bfd disable
Example:
switch(config-if)# ip ospf bfd disable
|
(Optional) Disables BFD on a OSPFv2 interface. The default value is enabled.
|
Step 6
|
show running-config ospf
Example:
switch(config)# show running-config ospf
|
(Optional) Displays the OSPFv2 running configuration.
|
Step 7
|
copy running-config startup-config
Example:
switch(config)# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD for Static Routes
You can configure BFD for static routes on an interface. You can optionally configure BFD on a static route within a virtual routing and forwarding (VRF) instance.
SUMMARY STEPS
1.
configure terminal
2. (Optional)
vrf
context
vrf-name
3.
ip route
route
interface
if
{
nh-address
|
nh-prefix
}
4.
ip route static bfd
interface
{
nh-address
|
nh-prefix
}
5.
(Optional) show ip route static
[
vrf
vrf-name
]
6.
(Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
vrf context
vrf-name
Example:
switch(config)# vrf context Red
switch(config-vrf)#
|
(Optional) Enters VRF configuration mode.
|
Step 3
|
ip
route
route
interface
{
nh-address
|
nh-prefix
}
Example
:
switch(config-vrf)# ip route 192.0.2.1 ethernet 1/2 192.0.2.4
|
Creates a static route Use the
?
keyword to display the supported interfaces.
|
Step 4
|
ip
route static bfd
interface
{
nh-address
|
nh-prefix
}
Example
:
switch(config-vrf)# ip route static bfd ethernet 1/2 192.0.2.4
|
Enables BFD for all static routes on an interface. Use the
?
keyword to display the supported interfaces.
|
Step 5
|
show ip route static
[
vrf
vrf-name
]
Example:
switch(config-vrf)# show ip route static vrf Red
|
(Optional) Displays the static routes.
|
Step 6
|
copy running-config startup-config
Example:
switch(config-vrf)# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD for IPv6
Configuring Global BFD Parameters for IPv6
BEFORE YOU BEGIN
You can specify either the IPv4 or the IPv6 address family when you configure BFD parameters.
SUMMARY STEPS
1. configure terminal
2. bfd [ipv4 | ipv6] interval [interval min_rx milliseconds multiplier interval-multiplier]
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
bfd [ipv4 | ipv6] interval [interval min_rx milliseconds multiplier interval-multiplier]
Example:
switch(config)# bfd ipv6 interval 50 min_rx 50 multiplier 3
|
Configures the BFD session parameters for all BFD sessions in the specified address family on the device.
The Tx and Rx intervals range between 50 and 999 milliseconds.
The multiplier ranges between 3 and 50.
|
Configuring Per Interface BFD Parameters for IPv6
BEFORE YOU BEGIN
BFD must be enabled on the device.
SUMMARY STEPS
1. configure terminal
2. interface type slot/port
3. bfd [ipv4 | ipv6] interval [interval min_rx milliseconds multiplier interval-multiplier]
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
interface type slot/port
Example:
switch(config)# interface ethernet 1/2
switch(config-if)#
|
Enters interface configuration mode.
Use the ? keyword to display the supported interfaces
|
Step 3
|
bfd [ipv4 | ipv6] interval [interval min_rx milliseconds multiplier interval-multiplier
Example:
switch(config-if)# bfd ipv6 interval 50 min_rx 50 multiplier 3
|
Configures the BFD session parameters for all BFD sessions in the specified address family on the device.
The Tx and Rx intervals range between 50 and 999 milliseconds.
The multiplier ranges between 3 and 50.
|
Configuring BFD for IPv6 on OSPFv3
You can configure BFD for IPv6 on the Open Shortest Path First Protocol (OSPFv3).
SUMMARY STEPS
1.
configure terminal
2.
router ospfv3
process-id
3.
bfd
4. (Optional)
show running-config ospf
5. (Optional)
copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
router ospfv3
process-id
Example:
switch(config)# router ospfv3 201
switch(config-router)#
|
Creates a new OSPFv2 process with a configured id.
|
Step 3
|
bfd
Example:
switch(config-router)# bfd
|
Enables BFD for this OSPFv3 peer. The default value is disabled
.
|
Step 4
|
show running-config ospfv3
Example:
switch(config-router)# show running-config ospfv3
|
(Optional) Displays the OSPFv3 running configuration.
|
Step 5
|
copy running-config startup-config
Example:
switch(config-router)# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD on IPv6 Static Routes
You can configure BFD for all IPv6 static routes on an interface.
PREREQUISITES
-
Ensure that BFD is enabled on the devices at each end of the static route.
-
Ensure that the BFD session parameters are configured.
SUMMARY STEPS
1. configure terminal
2. vrf context vrf-name
3. ipv6 route route interface {nh-address | nh-prefix}
4. ipv6 route static bfd network-interface {nh-address | nh-prefix}
5. (Optional) show bfd neighbors
6. (Optional) show ipv6 route static
7. (Optional) copy running-config startup-config
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
vrf context
vrf-name
Example:
switch(config)# vrf context Red
switch(config-vrf)#
|
(Optional) Enters VRF configuration mode to configure BFD on an IPv6 static route.
Specifies the VRF for the route to be tracked.
|
Step 3
|
ipv6
route
route
interface
{
nh-address
|
nh-prefix
}
Example
:
switch(config-vrf)# ipv6 route 1::5/64 ethernet 1/3 2::2
|
Creates an IPv6 static route.
-
Specify the IPv6 address for the route argument
-
Use the
?
keyword to display the supported interfaces.
-
Specify the next-hop (nh) address or prefix for this static route.
|
Step 4
|
ipv6
route static bfd
network-interface
{
nh-address
|
nh-prefix
}
Example
:
switch(config-vrf)# ipv6 route static bfd ethernet 1/3 2::2
|
Enables BFD for all IPv6 static routes on an interface.
-
Use the
?
keyword to display the supported interfaces.
-
Specify the next-hop (nh) address or prefix for this static route.
|
Step 5
|
show bfd neighbors
Example:
switch(config-vrf)# show bfd neighbors
|
(Optional) Displays information about BFD neighbors.
|
Step 6
|
show ipv6 route static
Example:
switch(config-vrf)# show ipv6 route static vrf Red
|
(Optional) Displays the static routes.
|
Step 7
|
copy running-config startup-config
Example:
switch(config-vrf)# copy running-config startup-config
|
(Optional) Saves this configuration change.
|
Configuring BFD Echo Mode for IPv6
The echo function is enabled by default. You can disable it for IPv4, IPv6, or all address families.
SUMMARY STEPS
1. configure terminal
2. interface type slot/port
3. [no] bfd [ipv4 | ipv6] echo
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
interface type slot/port
Example:
switch(config)# interface ethernet 1/2
switch(config-if)#
|
Enters interface configuration mode.
Use the ? keyword to display the supported interfaces
|
Step 3
|
[no] bfd [ipv4 | ipv6]
echo
Example
:
switch(config-if)# bfd ipv6 echo
|
Enables the echo function. The default is enabled.
To disable the echo function for the specified address family, use the no form of the command.
|
Configuring BFD Session Echo Interval for IPv6
You can configure the echo Rx interval for BFD sessions.
SUMMARY STEPS
1. configure terminal
2. interface type slot/port
3. [no] bfd [ipv4 | ipv6] echo-rx-interval interval
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
interface type slot/port
Example:
switch(config)# interface ethernet 1/2
switch(config-if)#
|
Enters interface configuration mode.
Use the ? keyword to display the supported interfaces
|
Step 3
|
[no] bfd [ipv4 | ipv6]
echo-rx-interval interval
Example
:
switch(config-if)# bfd ipv6 echo-rx-interval 500
|
Configures the echo Rx interval for the BFD session. The interval can range between 50 and 999 milliseconds.
To return the echo interval to the default value of 250 milliseconds, use the no form of the command.
|
Configuring a BFD Echo Interface for IPv6
Perform this task to configure the loopback interface as the source address for all echo frames.
SUMMARY STEPS
1. configure terminal
2. interface loopback number
3. ip address ip-address mask
4. ipv6 address {ipv6-address / prefix-length | prefix-name sub-bits / prefix-length}
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
interface loopback number
Example:
switch(config)# interface loopback 50
switch(config-if)#
|
Creates a loopback interface and enters interface configuration mode.
|
Step 3
|
ip address ip-address mask
Example:
switch(config-if)# ip address 192.108.1.27 255.255.255.0
|
Configures the IP address for the interface.
|
Step 4
|
ipv6 address {ipv6-address/prefix-length | prefix-name sub-bits / prefix-length}
Example:
switch(config-if)# ipv6 address 2001:DB8:c18:1::3/64
|
Configures the IPv6 address as the source address for all echo frames.
|
Configuring BFD Slow Timer for IPv6
Echo mode is enabled by default. You can configure the slow-timer value and disable or enable echo mode for an address family.
SUMMARY STEPS
1. configure terminal
2. interface type slot/port
3. bfd [ipv4 | ipv6] slow-timer [interval]
DETAILED STEPS
|
|
|
Step 1
|
configure terminal
Example:
switch# configure terminal
switch(config)#
|
Enters global configuration mode.
|
Step 2
|
interface type slot/port
Example:
switch(config)# interface ethernet 1/2
switch(config-if)#
|
Enters interface configuration mode.
Use the ? keyword to display the supported interfaces
|
Step 3
|
bfd [ipv4 | ipv6]
slow-timer [interval]
Example
:
switch(config-if)# bfd ipv6 slow-timer 6000
|
Configures the slow timer, in milliseconds, used in the echo function for the specified address family.
|