RE: CA for IOCs w/ dual NICs

["Jeff Hill" <johill@lanl.gov>]

> If both interfaces have addresses in the same IP 
> subnet, no server application can control which
> interface will get used for the TCP socket connection.  
> This is a limitation of the TCP/IP networking kernel, 
> not of the EPICS CA server software, so don't wait for 
> Jeff to try and fix it because I don't believe he can.

Strictly speaking, with the portable CA server library we have
the EPICS_CAS_INTF_ADDR_LIST configuration parameter. If Kate
were to set this parameter to the IP address of a network
interface then this server would receive TCP and UDP messages
only from the specified interface. I have not tested this in a
situation where the two network interfaces were on the same IP
subnet, but I believe that it would work. Of course, that
configuration option is currently not supported by the original
CA server still in use in the R3.13 and R3.14 IOC.

Jeff


> -----Original Message-----
> From: Andrew Johnson [mailto:anj@aps.anl.gov]
> Sent: Tuesday, April 19, 2005 2:27 PM
> To: Kate Feng
> Cc: Jeff Hill; tech-talk@aps.anl.gov
> Subject: Re: CA for IOCs w/ dual NICs
> 
> Kate Feng wrote:
> >
> > What I wish for CA server is that NIC2 does not "receive UDP
> search
> > messages and or connect TCP circuits destined for  NIC1 of
> the IOC and
> > other interfaces".   This  seems to match with the
> capabilities you
> > described.
> 
> You can arrange that with the existing software as long as you
> put NIC2
> on a different subnet than NIC1.  If both interfaces have
> addresses in
> the same IP subnet, no server application can control which
> interface
> will get used for the TCP socket connection.  This is a
> limitation of
> the TCP/IP networking kernel, not of the EPICS CA server
> software, so
> don't wait for Jeff to try and fix it because I don't believe
> he can.
> 
> - Andrew
> --
> Podiabombastic: The tendency to shoot oneself in the foot.