Skip to Content.
Sympa Menu

freetds - Re: [freetds] connect(2) for UDP

freetds AT lists.ibiblio.org

Subject: FreeTDS Development Group

List archive

Chronological Thread  
  • From: Peter Deacon <peterd AT iea-software.com>
  • To: FreeTDS Development Group <freetds AT lists.ibiblio.org>
  • Subject: Re: [freetds] connect(2) for UDP
  • Date: Wed, 17 Dec 2008 22:19:58 -0800 (Pacific Standard Time)

On Wed, 17 Dec 2008, James K. Lowden wrote:

Good point -- we had a server with three IPs on one network, so it could
have 3 web server instances each listening on port 80. The source
address of the SNMP UDP packets would end up being round-robined.

Is this a theory, or observed behavior?

If I send a message to a port at an address, I more or less expect an
answer back from the same place. Even if each machine in the cluster
listens to 1434, the internal cluster logic has to be simpler if each
machine answers its own queries....

UDP has no concept of connection. Each message stands alone.

If the server binds to all interfaces and there are multiple interfaces capable of reaching the client the source address of messages from the server should be concidered random/determined by the routing system.

Servers that need to make sure the IPs match up in both directions for security checking..etc will typically separatly bind to each local interface individually to ensure the source address from the client perspective are deterministic. A quick netstat should show how MSSQL is binding and what behavior to expect.

regards,
Peter




Archive powered by MHonArc 2.6.24.

Top of Page