Re: [Boost-users] [Boost.Asio] Udp::Socket->send_to

From: Andrew Holden (aholden_at_[hidden])
Date: 2008-05-30 08:49:32

Ryan McConnehey wrote:
> Nikolai N Fetissov wrote: 
>> Hi,
>>
>>Ryan McConnehey wrote:
>>> In using the Boost.Asio library, the Udp::Socket->send_to() function
>>> throws an error if the endpoint is unreachable.  I thought in udp
>>> datagrams its a send and forget mentality.  The send_to function would
>>> send the message even if the endpoint was unreachable.  Is there a
>>> setting I need to use for this to work?
>>
>> This probably means you don't have a route to the target host,
>> so your kernel returns with error from local TCP stack without
>> actually putting packet on the wire.
>   
> I thought udp didn't need a route to the target host.  As long as there is a connection to a hub the socket > would send the data out.  Don't a route to the target host mean tcp?

No, UDP/IP still needs the route.  It doesn't verify the destination is actually available or attempt any form of two-way communication, but it does need to determine which router will get the packet closer to its destination.