[dnsdist] anycast and TCP

[Jahanzeb Arshad]

We are running dnsdist with anycast routing for over two years now with 
a customer base of over 200K corporate and residential broadband 
subscribers. We are using this for 6 different data center locations. We 
are using dnsdist as load balancer with FRR (https://frrouting.org/) to 
run BGP with our IP gateways.

Anycast is layer 3 routing. It is transparent of upper layers (UDP/TCP). 
Anycast gives you IP reachability to the nearest node.

Regards
*Jahanzeb Arshad*

On 2/4/23 12:15, Lucas Rolff via dnsdist wrote:
> That's not correct, if that was the case, TCP applications in general 
> would not work in anycast setups, which obviously isn't the case.
>
> It's correct that if you'd end up getting rerouted all of a sudden, it 
> would trigger a reset, but the application would (likely) still 
> succeed after establishing the TCP connection again.
>
> Running DNS (and accepting TCP queries) in an anycasted setup is 
> rather common :) I run a few of such setups.
>
>
>> On 2 Apr 2023, at 14:08, Marco Mangione <marco.mangione at gmail.com> wrote:
>>
>> becouse of split path routing, there are 2 or more anycast node and 
>> network load balancing causes packet transmitted to the anycast 
>> address to alternate between those nodes
>>
>> Il giorno dom 2 apr 2023 alle ore 08:59 Lucas Rolff 
>> <lucas at lucasrolff.com> ha scritto:
>>
>>     > Because if traffic is forced on TCP, for example with a TC=1,
>>     not everything could work correctly.
>>
>>     Why not?
>>
>>     > On 2 Apr 2023, at 13:55, Marco Mangione via dnsdist
>>     <dnsdist at mailman.powerdns.com> wrote:
>>     >
>>     > Hi everyone,
>>     > I would like to open a conversation about a dnsdist+pdns setup
>>     in anycast mode, therefore multiple locations with multiple
>>     instances inside.
>>     > All OK if we talk about UDP, but what about TCP? Has anyone had
>>     any experience?
>>     >
>>     > Because if traffic is forced on TCP, for example with a TC=1,
>>     not everything could work correctly.
>>     >
>>     > M1
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>
>
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