var q Bfd6108653036 745 Union Blvd. Bethlehem. At BFD, everything is made in house and with lots of love. We use only the freshest ingredients and locally bought products. Win Tickets To Both Nights Of Live 105s NSSN And Backstage Passes The Baninbridge Fire Company invites you to celebrate 2017 Fire Prevention with us at the Bainbridge Fire House at 34 South 2. Read more. At clubhouse bfd our mission is to be a neighborhood gathering place serving quality bfd beerfooddrink without the pretense. quite simply we love exceptional. Stations made easy. Route planning around the station including maps and platforms. Show BFD route. Business and Finance Division Commissary and Trust Fund Department Commissary Products. Commissary products are readily available at unit commissaries. Bfdi MouthJeff Kronlages CCIE Study Blog Everything BFD. I sat down to start working on BFD three weeks ago thinking Id be done in a couple of days. Three weeks later Im finally starting blogging on it. To be fair, I missed a week to drinking heavily in California, but it still took a really look time to dive down every rabbit hole theres a lot of BFD features, and the documentation stinks, particularly when it comes to why would I want to use this. So what is BFD Bidirectional Forwarding Detection BFD is a high speed are you up protocol that other routing protocols subscribe to. It can detect link failures in milliseconds, with the potential for microseconds on the right platform. All routing protocols have some way of detecting failure, usually timer related. Tuning the timers can theoretically get you sub second failure detection in some protocols, but this produces unnecessary high overhead as the average IGP wasnt designed with that in mind. BFD was specifically built for fastlow CPU detection, and in the case of single hop, can offload a great deal of the checks to CEF by using echo mode more later, even on a typical router. Some high end platforms can even offload the entire BFD process to the linecard. The CEF or hardware offload makes BFD a major improvement over the other obvious choice, IP SLA. Scope of this document To give a granular understanding of BFD, but focused on the CCIE v. R S. On that note, I have covered every BFD function I can find, excluding ISIS and MPLS TE, as these are both out of scope for the v. R S lab. We will cover BFDs use with single hop BGP, OSPF, EIGRP, RIP, PIM, HSRP, static routes, hierarchical static routes and multi hop BGP and multi hop static routes. We will cover with and without Echo, and with and without authentication. We will discuss IPv. Well also cover BFD dampening. Some key items to know BFD has no neighbor detection. When the routing protocol needs to monitor a neighbor, it informs BFD, and BFD establishes the neighbor relationship at that point. Various routing protocols can piggyback a single BFD session. If you have BGP and EIGRP running between the same two subnets on the same two routers, theres no need to have two BFD sessions for checking the same exact topology. There are two versions, 0 and 1. While there are some deep programmatic differences between the two, those are out of scope for this document. The major difference for us is that v. Cisco equipment. The documentation says Cisco equipment can be backwards compatible with v. Cisco device, you can safely assume for the lab exam that were always talking about v. There are two modes, asynchronous and demand. Asynchronous is the normal BFD mode that youre used to when you think Cisco BFD continuous, high speed detection of neighbor failure. Demand mode is more of a steady state operation, where its assumed the neighbor and link are generally stable, but youd periodically want to check to see if its up. Cisco has output for the demand bit in show commands, and they also talk about it vaguely in the documentation in places, but best I can tell theres just no command to enable it at least not on my device CSR1. I read elsewhere that enabling echo mode more on echo mode later put the control packets in demand mode, but the demand bit is not set in these cases, so that appears incorrect. Perhaps it would work if the other neighbor initiatedRegardless, assume out of scope for the v. BFD is always unicast. BFD control packets are always UDP, sourced from 4. BFD echo packets are also UDP, and are sourced from 3. Lets start with basic, single hop configuration. This will be our topology As with many of my other blogs, I use GNS3 as an easy diagramming tool. In this case, I am not using GNS for the actual lab, because I have never been able to get BFD to work in GNS3. The second the BFD relationship tries to establish, dynamips hard locks. Instead, I am using CSR1. VMWare. Each routers gigabit interfaces are assigned 1. AB. X2. 4, where AB is the router numbers on the link, and X is the router number i. R2s Gig. 1 is 1. Gig. 2 is 1. 92. 1. Each router has a Loopback. X. X. X. X, where X is the router number i. R1s Loopback. 0 is 1. In addition, each routers gigabit interfaces are assigned AB X6. AB is the router numbers on the link, and X is the router number i. R2s Gig. 1 is 1. Each router has a Loopback. X X1. 28, where X is the router number i. R1s Loopback. 0 is 1 11. IPv. 6 unicast routing is enabled on all devices. For this section, well mostly be working with R1 and R2. R1conf t. R1configinterface Gigabit. Ethernet. 1. R1config ifbfd interval 3. R2configinterface Gigabit. Ethernet. 1. R2config ifbfd interval 3. Now with a routing protocol, youd probably expect some sort of output now. R1show bfd neighbor. R1. As I mentioned above, no auto discovery process. The routing protocol has to tell BFD its needed first, and where to establish its neighbor relationship. Its also very noteworthy from a debugging perspective that if you get the blank output I showed above, youre missing something locally. Having half a BFD session configured or having your authentication messed up will produce output with a status of Admin. Down. Lets get this working R1config ifip ospf 1 area 0. R1config ifip ospf bfd. R2config ifip ospf 1 area 0. R2config ifip ospf bfd. Now we should see some output. R1show bfd neighbor. IPv. 4 Sessions. Neigh. Addr LDRD RHRS State Int. Up Up Gi. R2 has a similar output referencing R1. Now that we have a base config up, lets test the detection. R2config ifshut. Jun 2. 1 0. 2 1. OSPF 5 ADJCHG Process 1, Nbr 2. Gigabit. Ethernet. FULL to DOWN, Neighbor Down BFD node down. Its hard to demonstrate speed in a blog, but it happens very fast. We see from the output that BFD told the routing protocol that its neighbor had been lost BFD node down. Lets bring the link back up. R2config ifno shut. The command usage is not as simple as it seems the variable names are terrible, in my opinion. Lets build a more confusing example R1config ifbfd interval 2. R2config ifbfd interval 2. The first value is the mintx and the second value is the minrx. I dont care for the names at all. R1 will be compared to mintx from R2, and a per direction transmission value will be calculated. In our scenario above, R1s mintx 2. R2s minrx 4. 00. The slower larger value wins. Clearly, 4. 00ms is longer than 2. R1 towards R2. Vice versa, R2s mintx is 2. R1s minrx is 5. R2 to R1. For output clarity I am going to disable echo mode for the moment not shown here and show the simplified output of show bfd neighbor detail Heres the relevant output Rx Count 4. Rx Interval ms minmaxavg 15. Tx Count 5. 8, Tx Interval ms minmaxavg 13. We see that our maximum Rx is 5. R2 to R1, and maximum Tx is 3. R1 to R2. It can sendreceive a touch faster than this, the idea being that if the BFD control packet doesnt arrive in under the maximum time, itll be considered lost. The multiplier is reasonably obvious, if you miss that many BFD control packets, consider the link failed. Since Ive got this output up, also noteworthy are. Registered Protocols What protocols are subscribed to this BFD sessionWe see OSPF and CEF here. Session state is UP and not using echo function. I mentioned I disabled echo. NY auto parts by owner1. Dec 8. Ladder racks for cargo vans1. Wolcott. pic. maphide this postingrestorerestore this postingfavorite this post. Dec 8. 19. 72 CAMARO REAR SEAT8. Akronmaphide this postingrestorerestore this posting1. Dec 8. 5 1. 6 8 lug chevy wheels1. BATAVIA. pic. maphide this postingrestorerestore this posting5. Dec 8. Weathertech floor liners 2. Infiniti G3. 7x5. 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