On Thu, 7 Apr 2005, Dave Shield wrote:
On Wed, 2005-04-06 at 08:33, Soori wrote:In every SNMP document it is stated that SNMP uses UDP as transport. Can any body tell me is there any specific reason to use SNMP over UDP and not TCP ?
TCP uses 3 way handshake before the real transmission starts, while UDP dosent need any such handshakes.
Also when there is congestion and consequently packet losses occurs, TCP retransmits the packets further adding to the congestion.
Sundeep.
As well as the question of behaviour in a failing network, that baskeböler mentions, there's another issue to consider.
When SNMP was first being developed, one of the aims was to make it as lightweight as possible, so that it could safely be included within embedded systems where processing resources might be at a premium. UDP is a significantly simpler protocol than TCP, so it was felt this could result in a smaller implementation footprint.
With the explosion in processing power, such concerns are now much less important.
Currently, the most important reason for running SNMP over UDP, is that this is the accepted standard arrangement. The whole point of network management is to be able to talk to a wide variety of networked kit. There's not much point in choosing a different transport, if half your boxes don't support it!
I think Net-SNMP supports both TCP and UDP.
Correct.
As far as the basic SNMP protocol is concerned, it doesn't actually care *what* transport is used. The transport is there to get a message from A to B. As long as the request gets there (and the response gets back again), you could run SNMP over Secret-Decoder-Ring if you really wanted to :-)
Net-SNMP implements a modular transport mechanism, so can support a variety of different transports (take a bow, John). These include UDP and TCP over both IPv4 and IPv6, IPX, AAL5, and local callbacks. None of this affects the basic operation of the agent or client tools.
But if you want to manage other kit, you must use transport mechanisms that they support.
Dave
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-- Sundeep.
