After you read the BFD Overview, which includes firewall models and interfaces supported, perform the following before configuring BFD:
The effectiveness of your BFD implementation depends on a variety of factors, such as traffic loads, network conditions, how aggressive your BFD settings are, and how busy the dataplane is.
- Create a BFD profile.If you change a setting in a BFD profile that an existing BFD session is using and you commit the change, before the firewall deletes that BFD session and recreates it with the new setting, the firewall sends a BFD packet with the local state set toadmin down. The peer device may or may not flap the routing protocol or static route, depending on the peer’s implementation of RFC 5882, Section 3.2.
- SelectandNetworkNetwork ProfilesBFD ProfileAddaNamefor the BFD profile. The name is case-sensitive and must be unique on the firewall. Use only letters, numbers, spaces, hyphens, and underscores.
- Select theModein which BFD operates:
- Active—BFD initiates sending control packets to peer (default). At least one of the BFD peers must be Active; both can be Active.
- Passive—BFD waits for peer to send control packets and responds as required.
- Configure BFD intervals.
- Enter theDesired Minimum Tx Interval (ms). This is the minimum interval, in milliseconds, at which you want the BFD protocol (referred to as BFD) to send BFD control packets; you are thus negotiating the transmit interval with the peer. Minimum on PA-7000, PA-5200 Series, and PA-5000 Series firewalls is 50; minimum on VM-Series firewall is 200. Maximum is 2,000; default is 1,000.The recommendation is to set theDesired Minimum Tx Intervalon a PA-7000 or PA-5000 Series firewall to 100 or greater; a value less than 100 is at risk of causing BFD flaps.If you have multiple routing protocols that use different BFD profiles on the same interface, configure the BFD profiles with the sameDesired Minimum Tx Interval.
- Enter theRequired Minimum Rx Interval (ms). This is the minimum interval, in milliseconds, at which BFD can receive BFD control packets. Minimum on PA-7000, PA-5200 Series, and PA-5000 Series firewalls is 50; minimum on VM-Series firewall is 200. Maximum is 2,000; default is 1,000.The recommendation is to set theRequired Minimum Rx Intervalon a PA-7000 or PA-5000 Series firewall to 100 or greater; a value less than 100 is at risk of causing BFD flaps.
- Configure the BFD Detection Time Multiplier.Enter theDetection Time Multiplier. The local system calculates the detection time as theDetection Time Multiplierreceived from the remote system multiplied by the agreed transmit interval of the remote system (the greater of theRequired Minimum Rx Intervaland the last receivedDesired Minimum Tx Interval). If BFD does not receive a BFD control packet from its peer before the detection time expires, a failure has occurred. Range is 2 to 50; default is 3.For example, a transmit interval of 300 ms x 3 (Detection Time Multiplier) = 900 ms detection time.When configuring a BFD profile, take into consideration that the firewall is a session-based device typically at the edge of a network or data center and may have slower links than a dedicated router. Therefore, the firewall likely needs a longer interval and a higher multiplier than the fastest settings allowed. A detection time that is too short can cause false failure detections when the issue is really just traffic congestion.
- Configure the BFD hold time.Enter theHold Time (ms). This is the delay, in milliseconds, after a link comes up before BFD transmits BFD control packets.Hold Timeapplies to BFD Active mode only. If BFD receives BFD control packets during theHold Time, it ignores them. Range is 0-120000. The default is 0, which means no transmitHold Timeis used; BFD sends and receives BFD control packets immediately after the link is established.
- (Optional—For a BGP IPv4 implementation only) Configure hop-related settings for the BFD profile.
- SelectMultihopto enable BFD over BGP multihop.
- Enter theMinimum Rx TTL.This is the minimum Time-to-Live value (number of hops) BFD will accept (receive) in a BFD control packet when BGP supports multihop BFD. (Range is 1-254; there is no default).The firewall drops the packet if it receives a smaller TTL than its configuredMinimum Rx TTL. For example, if the peer is 5 hops away, and the peer transmits a BFD packet with a TTL of 100 to the firewall, and if theMinimum Rx TTLfor the firewall is set to 96 or higher, the firewall drops the packet.
- Save the BFD profile.ClickOK.
- (Optional) Enable BFD for a static route.Both the firewall and the peer at the opposite end of the static route must support BFD sessions.
A BFD column on theIPv4orIPv6tab indicates the BFD profile configured for the static route.
- Selectand select the virtual router where the static route is configured.NetworkVirtual Routers
- Select theStatic Routestab.
- Select theIPv4orIPv6tab.
- Select the static route where you want to apply BFD.
- Select anInterface(even if you are using a DHCP address). TheInterfacesetting cannot beNone.
- ForNext Hop, selectIP Addressand enter the IP address if not already specified.
- (Optional) Enable BFD for all BGP interfaces or for a single BGP peer.If you enable or disable BFD globally, all interfaces running BGP will be taken down and brought back up with the BFD function. This can disrupt all BGP traffic. When you enable BFD on the interface, the firewall stops the BGP connection to the peer to program BFD on the interface. The peer device sees the BGP connection drop, which can result in a reconvergence. Enable BFD for BGP interfaces during an off-peak time when a reconvergence will not impact production traffic.If you implement both BFD for BGP and HA path monitoring, Palo Alto Networks recommends you not implement BGP Graceful Restart. When the BFD peer’s interface fails and path monitoring fails, BFD can remove the affected routes from the routing table and synchronize this change to the passive HA firewall before Graceful Restart can take effect. If you decide to implement BFD for BGP, Graceful Restart for BGP, and HA path monitoring, you should configure BFD with a larger Desired Minimum Tx Interval and larger Detection Time Multiplier than the default values.
A BFD column on the BGP - Peer Group/Peer list indicates the BFD profile configured for the interface.
- Selectand select the virtual router where BGP is configured.NetworkVirtual Routers
- Select theBGPtab.
- (Optional) To apply BFD to all BGP interfaces on the virtual router, in theBFDdrop-down, select one of the following and clickOK:
- (Optional) To enable BFD for a single BGP peer interface (thereby overriding theBFDsetting for BGP as long as it is not disabled), perform the following tasks:
- Select thePeer Grouptab.
- Select a peer group.
- Select a peer.
- In theBFDdrop-down, select one of the following:default—Uses only default settings.Inherit-vr-global-setting(default)—The BGP peer inherits the BFD profile that you selected globally for BGP for the virtual router.SelectingDisable BFDdisables BFD for the BGP peer.
- (Optional) Enable BFD for OSPF or OSPFv3 globally or for an OSPF interface.
A BFD column on the OSPFInterfacetab indicates the BFD profile configured for the interface.
- Selectand select the virtual router where OSPF or OSPFv3 is configured.NetworkVirtual Routers
- Select theOSPForOSPFv3tab.
- (Optional) In theBFDdrop-down, select one of the following to enable BFD for all OSPF or OSPFv3 interfaces and clickOK:
- (Optional) To enable BFD on a single OSPF peer interface (and thereby override theBFDsetting for OSPF, as long as it is not disabled), perform the following tasks:
- Select theAreastab and select an area.
- On theInterfacetab, select an interface.
- In theBFDdrop-down, select one of the following to configure BFD for the specified OSPF peer:default—Uses only default settings.Inherit-vr-global-setting(default)—OSPF peer inherits theBFDsetting for OSPF or OSPFv3 for the virtual router.SelectingDisable BFDdisables BFD for the OSPF or OSPFv3 interface.
- (Optional) Enable BFD for RIP globally or for a single RIP interface.
The BFD column on theInterfacetab indicates the BFD profile configured for the interface.
- Selectand select the virtual router where RIP is configured.NetworkVirtual Routers
- Select theRIPtab.
- (Optional) In theBFDdrop-down, select one of the following to enable BFD for all RIP interfaces on the virtual router and clickOK:
- (Optional) To enable BFD for a single RIP interface (and thereby override theBFDsetting for RIP, as long as it is not disabled), perform the following tasks:
- Select theInterfacestab and select an interface.
- In theBFDdrop-down, select one of the following:default—Uses only default settings).Inherit-vr-global-setting(default)—RIP interface inherits the BFD profile that you selected for RIP globally for the virtual router.SelectingNone (Disable BFD)disables BFD for the RIP interface.
- Commit the configuration.ClickCommit.
- View BFD summary and details.
- Select, find the virtual router you are interested in, and clickNetworkVirtual RoutersMore Runtime Stats.
- Select theBFD Summary Informationtab to see summary information, such as BFD state and run-time statistics.
- (Optional) Selectdetailsin the row of the interface you are interested in to view Reference: BFD Details.
- Monitor BFD profiles referenced by a routing configuration; monitor BFD statistics, status, and state.Use the following CLI operational commands:
- show routing bfd active-profile [<name>]
- show routing bfd details [interface<name>][local-ip<ip>][multihop][peer-ip<ip>][session-id][virtual-router<name>]
- show routing bfd drop-counters session-id<session-id>
- show counter global | match bfd
- (Optional) Clear BFD transmit, receive, and drop counters.clear routing bfd counters session-id all |<1-1024>
- (Optional) Clear BFD sessions for debugging.clear routing bfd session-state session-id all |<1-1024>
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