BFD flapping Cisco

Multiple BFD flapping on our Cisco ASR9000 TenGig

  1. s downtime. Below are the sample logs
  2. The BFD Dampening feature introduces a configurable exponential delay mechanism to suppress the excessive effect of remote node reachability events flapping with BFD. The BFD Dampening feature allows the network operator to automatically dampen a given BFD session to prevent excessive notification to the BFD clients, thus preventing unnecessary.
  3. Symptom: During Negative test phase on VxLAN Border Leaf N9236C, when do clear ip route vrf all * , will cause BFD session flap . Both clients BGP and ISIS will be impact. After adjust interval to 300ms , will no flap anymore . Conditions: Do cli command clear ip route vrf all Corner case observed: 1:When config BGP over logical port-channel to SPINE1 ,bfd keep flapping ( Only happened.
  4. Symptom: BFD session keep flapping continuously with error: interface Bundle-Ether1001.2 has gone down. Reason: Control timer expired Bidirectional Forwarding Detection (BFD) continuously flaps over Bundle VLANs (BVLAN). Selection of active member link to run the BFD session is distributed to each participating bfd_agent process. When things go wrong", multiple bfd_agents can accidently.
  5. None Symptom: Bidirectional Forwarding Detection (BFD) continuously flaps over Bundle VLANs (BVLAN). Conditions: One linecard hosting component links of the BVLAN is out of sync with the other linecards and is incorrectly trying to bring up the BFD session along with another linecard causing a Control Timer Expiry and constant flapping

Bidirectional Forwarding Detection Prerequisites for Bidirectional Forwarding Detection. Cisco Express Forwarding and IP routing must be enabled on all participating routers. 750 milliseconds 1000 milliseconds results in constant flapping of BFD and from 1000 milliseconds •The Cisco 10720 Internet router does not support the following BFD features: - Demand mode - Echo packets - BFD over IP Version 6 • On the Cisco 12000 series router, asymmetrical routing between peer devices may cause a BFD control packet to be received on a line card other than the line card that initiated the session. In this special case, the BFD session between the routing peers.

IP Routing: BFD Configuration Guide, Cisco IOS XE Release

  1. Cisco Bug: CSCvc91689 - BFD flapping during SSO. Last Modified . Nov 25, 2019. Products (1) Cisco Catalyst 6000 Series Switches ; Known Affected Releases . 15.3(1)S. Description (partial
  2. configuration: hw-module bfd-hw-offload enable If BFD timer on ASR9k is lesser than the timer value set on neighbor. Typical configuration that can lead to issue: ASR9k: router isis mpls_net interface TenGigE_X bfd
  3. For more details about BFD, see the Cisco IOS IP Routing: BFD Configuration Guide. How to Decrease BGP Convergence Time Using BFD. Prerequisites. Cisco Express Forwarding (CEF) and IP routing must be enabled on all participating routers. BGP must be configured on the routers before BFD is deployed
  4. Bidirectional Forwarding Detection (BFD) BFD (Bidirectional Forwarding Detection) is a super fast protocol that is able to detect link failures within milliseconds or even microseconds.. All (routing) protocols have some sort of mechanism to detect link failures. OSPF uses hello packets and a dead interval, EIGRP uses hello packets and a.
  5. Enables BFD between the local networking devices and the neighbor whose IP address you configured to be a BGP peer in Step 3. In the example in Step 3, the IP address was set up as the BGP peer. In this example, BFD is enabled between the local networking devices and the neighbor Step 6
  6. imize the impact of a flapping interface on.
  7. Very aggressive BFD timers could cause a link to be declared down even when there is only a slight variance in the link quality, which could cause flapping and other disastrous behavior to ensue. The best current practice with regards to BFD timers is to set a transmit and receive interval of 300ms and a multiplier of 3, which equates to 900ms.

If the BFD session is tracking only the BGP session between SWR 1 and 2 and if the BDF is flapping only this session must be impacted. In production I saw one or twice such a case, both of them was related to some software issues. If you are sure that the BFD is monitoring only the BGP session there is a big probability to be a software issue I don't know if you're configuring BFD with OSPF or BGP but sample config here is for BFD on interface, I believe this is the same as BFD for static routing on Cisco. Arista1 et10/1—-L3—-et10/1 Arista2 . Arista1(config-if-Et10/1)#sh active interface Ethernet10/1 no switchport ip address bfd static neighbor bfd ech Emne: [c-nsp] ME3600 BFD flapping Hi, We have a huge problems with BFD flapping on ME3600.It`s random event on two 3600 connected to the same end system. a.) First we thought that interface output drops causing BFD flapping.Than we configure a a output queue policy to eliminate interface output drops. BFD flapping still there : The Bidirectional Forwarding Detection (BFD) protocol is a simple hello mechanism that detects failures in a network. BFD works with a wide variety of network environments and topologies. A pair of routing devices exchange BFD packets. Hello packets are sent at a specified, regular interval. A neighbor failure is detected when the routing device stops receiving a reply after a specified interval This module describes the configuration of bidirectional forwarding detection (BFD) on the Cisco ASR 9000 Series Router. Bidirectional forwarding detection (BFD) provides low-ove

See the Restrictions for Bidirectional Forwarding Detection section for more information on BFD routing protocol support in Cisco IOS software. 750 milliseconds 1000 milliseconds results in constant flapping of BFD and from 1000 milliseconds. The Cisco implementation of BFD for Cisco IOS Release 12.2(18)SXE also supports only Layer 3. I also found some occasions in the router logs where the BGP session was flapping due to BFD packets being lost between our router and AT&T's router, again because QoS and traffic shaping hadn't been setup properly on the Cisco router and the traffic was bursting well past the 100Mbps allocated from AT&T and that traffic was being dropped. Figure 1: Topology for the EBGP Case. Figure 2 shows the topology for the RR case. Router R1 is the RR, and Router R3 is the client. Router R1 has IBGP sessions with Routers R2 and R3. All sessions have the family inet-vpn unicast statement configured. If the R1-R3 session flaps, the R1-R2 and R1-R4 sessions flap also Configure BFD. After you read the BFD Overview, which includes firewall models and interfaces supported, perform the following before configuring BFD: Configure one or more Virtual Routers. Configure one or more Static Routes if you are applying BFD to static routes. Configure a routing protocol ( BGP, OSPF, OSPFv3, or RIP ) if you are applying. • BFD is unaware of underlying L2 link bundle members. • A 4x10GigE L2 bundle (802.3ad) would appear as a single L3 adjacency. BFD packets would be transmitted on a single member link, rather than out all 4 links. • A failure of the link with BFD on it would result in the entire L3 adjacency failing

In addition, many Cisco devices have reserved Vlan ranges that are hard to modify (i.e., you have to reboot the switches for changes to take effect). Vlan 3967 is a Vlan which is not reserved on any Cisco switching platform and ideal for ACI. Node ID Settings - Spines should be numbered between 101-199; Leafs should be numbered 200 and above EX Series,QFabric System,QFX Series. The Bidirectional Forwarding Detection (BFD) protocol is a simple mechanism that detects failures in a network and works in a wide variety of network environments and topologies. In BFD operation, switches exchanges BFD hello packets at a specified interval and detect a neighbor failure if they do not receive a reply after a specified interval Cc: rtg-bfd@ietf.org, jhaas@nexthop.com, dward@cisco.com, d.katz@juniper.com Subject: Re: a draft about how BFD notifying the state change to applications X-BeenThere: rtg-bfd@ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: RTG Area: Bidirectional Forwarding Detection DT <rtg-bfd.ietf.org> Understanding BFD for BGP. The Bidirectional Forwarding Detection (BFD) protocol is a simple hello mechanism that detects failures in a network. Hello packets are sent at a specified, regular interval. A neighbor failure is detected when the routing device stops receiving a reply after a specified interval BFD session is not coming up or it went down; BFD flapping; The status of BFD on the local router using 'show bfd session' command should show a status of UP (constantly): user@Router> show bfd session Detect Transmit Address State Interface Time Interval Multiplier Up t3-0/3/1.0 3.000 1.000 3 Up t3-0/3/0.0 3.000 1.000 3 Up 6.000 1.000 3 3 sessions, 5 client

Cisco Bug: CSCvb03793 - BFD flapping issu

BFD have been such that convergence happens as soon as BFD signals its client (the IGP, in this case) of an issue on the link. If BFD is fast but the IGP is still waiting around to run its SPF process, the benefits of BFD become marginalized. Then again, with (r)LFA, perhaps the case for BFD is slowly going away BFD is performing rapid link down detection. When that happens the link will go straight down. When the link comes back up, the carrier-delay will hold it back from being signal as UP to the routing protocol for 5 seconds. Dampening is also enabled such that if this link continues to flap and violates the damping threshold it will be supressed. ISSU/Reboot/Optional SMU, Bfd session flapping after rsp switchover in 712 06I when hosted across LS Login and Service Contract Required asr9k-sysadmin-6.6.3.CSCvt12408.tar Advisorie Bidirectional Forwarding Detection Protocol. Bidirectional Forwarding Detection Protocol is a relatively new tool that allows to significantly lower dynamic routing protocol convergence times. Previously faster convergence in the LAN was often achieved by tuning protocol hello/keepalive timers. A good example is Fast Hello setting for OSPF Bidirectional Forwarding Detection (BFD) is a network protocol that is used to detect faults between two routers or switches connected by a link.It provides low-overhead detection of faults even on physical media that doesn't support failure detection of any kind, such as Ethernet, virtual circuits, tunnels and MPLS Label Switched Paths.. BFD establishes a session between two endpoints over a.

Cisco Bug: CSCsx80072 - BFD keep flapping after with msg

RFC 7726 Clarifications to RFC 5884 January 2016 allowing a new BFD session to be created is outside the scope of this document. Such policies or procedures could consider availability of system resources before allowing a session to be created. When the egress LSR disallows the creation of a BFD session due to policy, it MUST drop the MPLS Echo request message The open and resolved bugs for this release are accessible through the Cisco Bug Search Tool.This web-based tool provides you with access to the Cisco bug tracking system, which maintains information about bugs and vulnerabilities in this product and other Cisco hardware and software products BFD sends Hello packets every second, by default. You can increase this interval to a maximum of 5 minutes (300000 milliseconds) by including the bfd color hello-interval configuration command. (Note that you specify the OMP Update packet interval in seconds and the BFD Hello packet interval in milliseconds.

Route flapping. In computer networking and telecommunications, route flapping occurs when a router alternately advertises a destination network via one route then another (or as unavailable, and then available again) in quick sequence. Route flapping is caused by pathological conditions (hardware errors, software errors, configuration errors. When five packets are missed (so after 250 ms) the neighbor is considered dead. BFD then must be applied to each individual BGP session as desired: ! router bgp 65065. neighbor fall-over bfd. ! BFD must be enabled on both routers in order to be used for the BGP session between them

Cisco Bug: CSCsl12615 - bfd session flapping continuously

YANG modules from standards organizations such as the IETF, The IEEE, The Metro Ethernet Forum, open source such as Open Daylight or vendor specific modules - YangModels/yan If the topology change is caused by a flapping link then the router would run SPF over and over again, increasing its load. 3.3l: BFD (Bidirectional Forwarding Detection) BFD (Bidirectional Forwarding Detection) 3.3m: Loop Prevention Mechanisms. Prefix-List; The Best Dollar You've Ever Spent on Your Cisco Career! Full Access to our. To create a custom template for BFD, select the Factory_Default_BFD_Template and click Create Template. The BFD template form is displayed. The top of the form contains fields for naming the template, and the bottom contains fields for defining BFD parameters. You may need to click a tab or the plus sign (+) to display additional fields Internet Engineering Task Force (IETF) V. Govindan Request for Comments: 7726 K. Rajaraman Updates: 5884 Cisco Systems Category: Standards Track G. Mirsky ISSN: 2070-1721 Ericsson N. Akiya Big Switch Networks S. Aldrin Google January 2016 Clarifying Procedures for Establishing BFD Sessions for MPLS Label Switched Paths (LSPs) Abstract This document clarifies the procedures for establishing.

Bidirectional Forwarding Detection 712. Asynchronous Mode 713. Asynchronous Mode with Echo Function 715. Configuration and Verification 715. Troubleshooting BFD Issues 724. BFD Session Not Coming Up 724. BFD Session Flapping 725. BGP Fast-External-Fallover 726. BGP Add-Path 726. BGP best-external 738. BGP FRR and Prefix-Independent Convergence. Hi all ! I have a flapping OSPF adjacency between FULL to EXCHANGE which I'm not able to solve. This adjacency is between a Juniper M320 (JunOS 9.3S5.1) and a Cisco uBR7225VXR (CMTS). Both of the adjacency are in the global routing table (no VRF). Hello, interval, dead time are ok => adjacency passed the TWO-WAY state BFD. Bidirectional Forwarding Detection (BFD) is a lightweight protocol designed to detect liveliness over links/bundles. BFD is: Designed for sub second failure detection Any interested client (OSPF, HSRP, BGP) registers with BFD and is notified when BFD detects loss All registered clients benefit from uniform failure detectio FHRP. Part 1. HSRP v1 and v2. The Hot Standby Router Protocol (HSRP) is one of the First Hop Redundancy Protocols (FHRP) designed to allow for transparent fail-over of the gateway. IEFT version of this protocol is Virtual Router Redundancy Protocol (VRRP). Cisco implements a proprietary version of FHRP - Gateway Load Balancing Protocol Designing Scalable OSPF Design. The ability to scale an OSPF internetwork depends on the overall network structure and addressing scheme. As outlined in the preceding sections about network topology and route summarization, adopting a hierarchical addressing environment and a structured address assignment are the most important factors in determining the scalability of your internetwork

Bidirectional Forwarding Detection - Cisc

Cisco Bug: CSCvc91689 - BFD flapping during SS

  1. Active Oldest Votes. 1. If the link flaps OSPF will run the SPF algorithm afresh to re-calculate the shortest path to all available destinations. you can change the throttle numbers to make the network more stable. The default timers are below. Initial SPF schedule delay 5000 msecs. Minimum hold time between two consecutive SPFs 10000 msecs
  2. 1.77 MB. Reboot/Recommended SMU, Cisco IOS XR Software for Cisco ASR 9000 Routers Slow Path Forwarding Vulnerability. Login and Service Contract Required. asr9k-px-6.2.3.CSCvv09115.tar. Advisories. 17-Nov-2020. 97.71 MB. Reboot/Recommended SMU, l2fib_mgr crash in SIP-700 when router configured with evpn and multicast
  3. Specifies a maximum flapping suppression time for a BFD session. The value is an integer ranging from 1 to 3600000, in milliseconds. The default value is 15000
  4. Basically the IGP is used for transport through your core network. BGP is used to learn external prefixes (such as routes out to the internet, or as Daniel says, routes to DMVPN or a WAN of some sort). If you do look at using iBGP heavily in your internal network you need to start thinking about full mesh requirements
  5. Internet-Draft OSPF Strict-Mode for BFD December 2020 successful or flapping of the BFD session. In this case, traffic that gets forwarded over such a link may experience packet drops while the failure of BFD session establishment would not enable fast routing convergence if the link were to go down or flap
  6. imizes the impact of the flapping on services. The larger value of the two.

Cisco Bug: CSCvf97057 - BFD sessions in XR DUT flaps if

When two EBGP routers that are directly connected do not form a working BGP neighbor adjacency there could be a number of things that are wrong: Layer 2 down preventing us from reaching the other side. Layer 3 issue: wrong IP address on one of the routers. Access-list blocking TCP port 179 (BGP) We have 3 Cisco NCS 6000 Series manuals available for free PDF download: Configuration Manual, Manual Cisco NCS 6000 Series Configuration Manual (498 pages) IOS XR Release 6.4. The difference now in milliseconds. The hard part is to convince your ISP to configure BFD on their side. At this moment Cisco supports BFD on Ethernet interfaces only and only for directly connected BGP peers, i.e. no multi-hop BGP. BFD requires UDP ports 3784 and 3785 to be open in case you have ACL applied to your uplink interface Method for ensuring bidirectional forwarding detection reliability and label switching path equipment US9094344B2 (en) * 2011-09-16: 2015-07-28: Cisco Technology, Inc. Establishing a bidirectional forwarding detection (BFD) asynchronous mode session without knowing a Prior layer-2 or layer-3 informatio

IP Routing: BGP Configuration Guide - BGP Support for BFD

  1. _rx 20 multiplier 3 Note: --> 30 is the hello timer which specifies the frequency of BFD packets sent by the router
  2. For more information, please visit: https://supportforums.cisco.com/community/netpro/network-infrastructure/switching?referring_site=YouTube&channel=videoThi..
  3. Refer to Route Selection in Cisco Routers for more information. Note: When EBGP peers are configured to reach each other with default routes, the BGP neighborship does not appear. This is done in order to avoid route flapping and routing loops. A ping to confirms the solution. RTR-A#ping Type escape sequence to abort
  4. Asynchronous is the normal BFD mode that you're used to when you think Cisco BFD: continuous, high-speed detection of neighbor failure. Demand mode is more of a steady-state operation, where it's assumed the neighbor and link are generally stable, but you'd periodically want to check to see if it's up

Bidirectional Forwarding Detection (BFD

Cisco Content Hub - Implementing BF

When it comes to fast convergence, first thing that we need to understand what is convergence? Convergence is the time between failure and the recovery. Link, circuits, routers, switches all eventually fails. As a network designers, our job is to understand the topology and whenever there is qrequirement, add backup link or node. Of Four necessary steps in routing fast convergence Read More BFD + OSPF + CCR1036 Issue. Fri Feb 06, 2015 2:46 am. Hi. I have a few CCR1036-8G-2S+, (6.22) I tried turning on BFD with OSPF. My first hurdle was BFD doesn't work by itself ! I then associated it with a OSPF interface, which had 4 nodes on it. Turned it on all 4 nodes.. worked for a while then up / down flapping. Network Programmability Sale. Save 25% on select DevNet and network programmability e-learning courses from the Cisco Learning Network Store. Join us June 14th-16th, 2021. Learn more Thanks Nitin On 4/5/11 10:44 AM, Rajeev Nair <rajeenai@cisco.com> wrote: > Hi Sachiv, > > Cisco NX-OS sprays the BFD frames on all links (not just FOP). So even-if u > flap one link, session will stay up. That may be the reason why your BFD > session is not flapping. > > thanks & regards > Rajeev > > On Apr 1, 2011, at 12:16 AM, sachiv wrote.

/routing ospf interface add interface=all use-bfd=yes BGP. Similar to OSPF, only one option per BGP peer to enable BFD /routing bgp peer add remote-address=x.x.x.x remote-as=xxxxx use-bfd=yes Interoperability. For interoperability with Cisco make sure to disable echo mode (it is enabled on Cisco by default), since it's not supported on MT An SD-WAN router with connectivity to three different transports (and colors) would have three TLOCs. Exchanging these TLOCs allows the arbitrary (or full-mesh) topology of the SD-WAN fabric to be built. Put simply, TLOCs are data plane setup instructions sent by each WAN Edge to the vSmart. The vSmart then distributes the maps to the other WAN.

Clarifying BFD and BFD Echo - NetCraftsme

flapping to validate the stability and robustness of the implementation handling abnormal behavior of internet network. Cisco EIGRP : Configuration Options : RFC 5881 - Bidirectional Forwarding Detection (BFD) for IPv4 and IPv6. Internet Engineering Task Force V. Govindan Internet-Draft K. Rajaraman Updates: 5884 (if approved) Cisco Systems Intended status: Standards Track G. Mirsky Expires: April 16, 2016 Ericsson N. Akiya Big Switch Networks S. Aldrin Google October 14, 2015 Clarifications to RFC 5884 draft-ietf-bfd-rfc5884-clarifications-04 Abstract This document.

In the last article, I explained how to configure the Cisco 6500 in VSS configuration, but how does the VSS reacts during a failure? There are three possible scenarios: Link failure within a multichassis Cisco etherchannel link Active supervisor engine failure VSL failure Scenario #1: Link failure within a multichassis Cisco etherchannel link Availability is not affected for those data [ Notify list changed from Jeffrey Haas <jhaas@pfrc.org>, draft-ietf-bfd-rfc5884-clarifications@ietf.org, bfd-chairs@ietf.org, aretana@cisco.com to (None) timer is used to introduce hysteresis to reduce flapping - but it would nice to say one way or the other The IESG has received a request from the Bidirectional Forwarding Detection WG. BFD is supported by VRRP on Cisco devices and provides a much faster response time than IP SLA. It is always best practice to introduce a delay in the response to an IP SLA detection as a single lost ping may not be an indication of a loss of connectivity, and could result in undesirable flapping To explicitly configure BFD to perform PMTU discovery, use the bfd color pmtu-discovery configuration command. However, you can choose to instead use ICMP to perform PMTU discovery: vEdge(config-vpn)# interface interface-name pmtu. BFD is a data plane protocol and so does not run on vBond, vManage, and vSmart devices

What's the BFD with BFD? - ShortestPathFirs

  1. If the FW is deployed between two routers, and the routers detect each other through BFD, you are advised to properly prolong the BFD time (longer than 100 ms is recommended) to prevent BFD flapping resulting from occasional network congestion
  2. Comparison with Bidirectional Forwarding Detection Similarly to UDLD, the Bidirectional Forwarding Detection (BFD) protocol is intended to detect faults in the path between two network nodes. However, BFD is supposed to operate independently of media, data protocols, and routing protocols
  3. Cisco Technology, Inc. BFD rate-limiting and automatic session activation US20070180105A1 (en) 2006-01-30: 2007-08-02: Clarence Filsfils: Technique for distinguishing between link and node failure using bidirectional forwarding detection (BFD) US20070245034A1 (en) * 2006-04-18: 2007-10-18: Retana Alvaro
  4. C H A P T E R Implementing BFD This module describes the configuration of bidirectional forwarding detection (BFD) on the Cisco ASR 9000 Series Router. Bidirectional forwarding detection (BFD) provides low-overhead, short-duration detection of failures in the path between adjacent forwarding engines
  5. This document describes the configuration of BFD, DLDP, VRRP, SmartLink, CFM, EFM, Y.1731 and MAC swap loopback to ensure reliability on the device. About This Document. Introduction to Reliability. Levels of Reliability Requirements. Reliability Specifications
  6. Elsewhere in the thread you have mentioned that you are using Cisco ME3600 devices. If you disable BFD echo mode you will be able to get low timers on these devices. Echo mode is enabled by default on IOS when you enable BFD under an interface, which these devices don't support, so you need to explicitly disable it

If you configured GRE tunneling before you might have encountered the following error: %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing. What happened is that your router has learned the destination IP address for the tunnel interface through the tunnel itself. As a result it removed the previous entry for the tunnel. Pass your Cisco 350-401 certification exam with Marks4sure valid 350-401 practice test questions answers dumps with 100% passing guarantee. Independence Day Flat 55% Discount Offer - Ends in 0d 00h 00m 00s - Coupon code: 63r5995 OSPF towards Cisco, LLS Hi, Anyone have any experience with the LLS (L-bit) that most Cisco will have enabled default. As far as I can see in the logs my Cisco box will send with option 0x52, and the Fortigate will send with option 0x42 (that I figure is the LLS option) I am having issues with ospf flapping massivly between loading/full on the Cisco end - and was wondering if anyone else have. Enable BFD on the join-interfaces: bfd interval 50 min_rx 50 multiplier 5 Configure BFD within the IGP connecting the data centers: router ospf 555 bfd all-interfaces Configure the following EEM script (Note: I had to modify the one Cisco provided in the docmentation as I was not getting the new adjacency alert in the syslog Edition: 1st. Book. ISBN-10: 1-58714-464-6. ISBN-13: 978-1-58714-464-6. The definitive guide to troubleshooting today's complex BGP networks. This is today's best single source for the techniques you need to troubleshoot BGP issues in modern Cisco IOS, IOS XR, and NxOS environments

BFD/BGP causing weird issues - learningnetwork

Arista EOS Central - bfd between arista and cisc

x@loophole> show bfd session Detect Transmit Address State Interface Time Interval Multiplier Down st0.1 0.000 1.000 3 Down st0.2 0.000 1.000 3 2 sessions, 2 clients Cumulative transmit rate 2.0 pps, cumulative receive rate 0.0 pp This document describes IP Unicast Routing configurations supported by the switch, including the principle and configuration procedures of IP Routing Overview, Static Route, RIP, RIPng, OSPF, OSPFv3, IS-IS(IPv4), IS-IS(IPv6), BGP, Routing Policy ,and PBR, and provides configuration examples OSPF Graceful Restart directs OSPF neighbors to continue using routes through a firewall during a short transition when it is out of service. This behavior increases network stability by reducing the frequency of routing table reconfiguration and the related route flapping that can occur during short periodic down times Bidirectional Forwarding Detection. Cisco.com DA: 13 PA: 50 MOZ Rank: 63. Cisco IOS Release 12.4 (9)T supports BFD Version 1 as well as BFD Version 0; All BFD sessions come up as Version 1 by default and will be interoperable with Version 0; The system automatically performs BFD version detection, and BFD sessions between neighbors will run in the highest common BFD version between neighbors