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12c Database : Network enhancements – DEFAULT_SDU_SIZE to 2M

How many you know this structure at first glance, I am sure the old DBA junkies will say what this called immediately, but for those who does not know this diagram is called Network OSI diagram for Oracle and layers between client and database servers and how oracle connects.

Oracle uses different methods to connect to database server and when used Oracle Net it uses the above network model to communicate with Oracle database. Oracle client has to be installed in the other end and it can communicate using Net layer and database layer uses same Net 8 foundation layer to listen the requests.

OSI Model depicts the following,

 

Layer#

Name

Description

7

Application

Standard communication services and applications that everyone can use

6

Presentation

Layer that takes data from application and presents it  in a format that is recognized by other layers; Functions like character set conversion is done by this layer

5

Session

Establishes, maintain & end connections

4

Transport

Delivers data without errors in sequence and no data loss or duplications. Large messages can be delivered but is constrained by message size limits imposed by the network layer.

3

Network

Controls the way data will be sent to recipient ; Factors like the physical path the data should take based  etc are performed by this layer. This layer translates logical addresses, or names, into physical addresses, performs routing

2

Data Link

Handles the transfer of data across the network ; It  establishes and terminates the logical link between two nodes.

1

Physical

The lowest layer of the OSI  is generally concerned with the transfer of data medium like optical or electrical medium etc.

 

Okay back to post now, the bold part above.

Session Data Unit(SDU) is the session layer responsible for  sending/receiving data from transport layer.  See table below for OSI diagram. Generally increasing the value of SDU can result in improved performance, efficient network utilization when transmitting large amounts of data. 

However until Oracle 11g  the SDU size was limited  to 64K. Starting with Oracle12c, support for  SDU  is increased to 2M thereby allowing efficient use of  high bandwidth network.

Very useful in dataguard environments where you have network bandwidth issues.

SDU can be set at  database level by configuring DEFAULT_SDU_SIZE parameter in sqlnet.ora or SDU listener.ora parameter. On the client size SDU can set be by configuring DEFAULT_SDU_SIZE parameter in client sqlnet.ora or SDU tnsnames.ora parameter.

January 29th, 2014 | Tags: , , , , | Category: 12c Database

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