Company XYZ was not satisfied with the reconvergence time OSPF is taking. BFD was implemented to try to reduce the reconvergence time, but the network is still experiencing delays when having to reconverge. Which technology will improve the design?
also, OSPF has faster convergence times than BGP
https://www.techtarget.com/searchnetworking/tip/BGP-vs-OSPF-When-to-use-each-protocol
https://community.fs.com/blog/ospf-vs-bgp-routing-protocol-choice.html
https://www.linkedin.com/advice/0/how-do-you-integrate-ospf-bgp-other-routing-protocols
It might be ospf fast hellos; subsecond hellos, eg. 200ms hello / 1 sec dead:
https://content.cisco.com/chapter.sjs?uri=/searchable/chapter/content/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/xe-16-5/iro-xe-16-5-book/iro-fast-hello.html.xml#GUID-9C62354B-68B6-432A-BCC6-FE927B1F8ABE
- BFD echo is by default enabled when configuring BFD.
- BGP, even slower
- Change the OSPF hello and dead intervals - should have stated "lower", also less effective than fast hellos.
Could it be C? The OSPF domain is so big that it takes so much computing power to recalculate and reconverge when a change occurs?
Switching to BGP is not the worse idea. Also because BFD and fast hellos are somewhat close when thinking about the impact they have on convergence times. One could argue that they could exacerbate the situation by consuming more CPU cycles.
B, with BFD echo, you can have more tighter timers, if we reducing OSPF timers would have achived the required convergence timer, customer would not have implemented BFD at first place.
By use this, dead interval can be 1 second and hello packet can be sub-second.
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/xe-3s/iro-xe-3s-book/iro-fast-hello.pdf
Direction is correct but not this configuration. Minimum Hello interval is 1 second, and dead interval is minimum 3 times as 3 seconds, the convergency time is still need 3 seconds.
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