On Thu, Apr 16, 2015 at 2:03 PM, Bob Harold <rharo...@umich.edu> wrote:
> We use ExaBGP to query the DNS process locally and advertise/withdraw > routes. > > We use BFD between the server and the router to detect link failure (or > server crash): > The BFD (Bidirectional Forwarding Detection) protocol is designed to > provide > rapid detection of communication failures between two devices. Routing > protocols can use BFD state to rapidly (< 1 second) withdraw routes in the > event of a failure, without having to wait for a routing protocol timeout > (3 minutes by default for BGP). > > Seems to work well. > > -- > Bob Harold > But that only protects from the system going down, not the DNS server failing in some manner. We used a monitor that actually made test queries to the server and then used bgpd to pull the anycast address down after N consecutive failures or more than M of the last K queries. I no longer have access to the trivial script since I retired. It's really harder than it looks to do right and I don't think my code was adequately rigorous, but was capable of responding to most issues. I'm sure more heuristics really needed to be added. -- Kevin Oberman, Network Engineer, Retired E-mail: rkober...@gmail.com
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