Document ID: 11245.1
Subject: Oracle MultiProtocol Interchange
Last Modified: 05 Mar 94
Author: RBEARD and MJARVIS
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COMMONLY ASSERTED MYTHS ABOUT THE ORACLE MULTIPROTOCOL INTERCHANGE
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Recent questions have indicated that there are some common misconceptions about
the Oracle MultiProtocol Interchange. In order to clarify precisely what is
and isn't possible with the Oracle MultiProtocol Interchange, Oracle's Network
Products Division hereby presents their first "Commonly Asserted Myths about
the Oracle MultiProtocol Interchange".
This Q&A session is also available from Inventory, part number A16618.
Q. What is the name of the Product?
A. It is called the "Oracle MultiProtocol Interchange". We are currently
seeking this name as a trademark. The product has inevitably been referred
to as the "MPI", but we would prefer you to use the full name.
Q. What is the Oracle MultiProtocol Interchange?
A. It is an Oracle product that allows SQL*Net V2 clients running on a specific
protocol to connect to SQL*Net V2-based servers which are running on other
protocols. The Oracle MultiProtocol Interchange enables connections between
clients and servers over unlike protocols transparently.
Q. Will the Oracle MultiProtocol Interchange work with SQL*Net V1?
A. No. The Oracle MultiProtocol Interchange is designed for use with
SQL*Net V2 only and will not work with SQL*Net V1.
Q. But I heard that the Oracle MultiProtocol Interchange will enable me to
connect SQL*Net V1 clients to SQL*Net V2-only servers and vice-versa.
Is this true?
A. No. The Oracle MultiProtocol Interchange does not work with SQL*Net V1 at
all. You can use both SQL*Net V1 and SQL*Net V2 in your network at the same
time, but only SQL*Net V2-based products will be able to use the Oracle
MultiProtocol Interchange.
Q. My customer already has routers in their network that handle multiple
protocols. Why do they need the Oracle MultiProtocol Interchange?
A. A router can route multiple protocols between two or more networks, but
the endpoints of each connection going through a router must use the same
protocol. A router is therefore different from the Oracle MultiProtocol
Interchange in that the Oracle MultiProtocol Interchange can route data
between endpoints that use different protocols.
Q. My customer already has a protocol gateway in their network. Doesn't this
do the same job as an Oracle MultiProtocol Interchange?
A. Protocol gateways generally only join two protocols together in one
direction only. In contrast, the Oracle MultiProtocol Interchange supports
as many protocols as will run on a single platform and is bidirectional.
Protocol gateways also transmit data using encapsulation, which makes them
incompatible with SQL*Net in many cases.
Q. My customer has a protocol converter in their network. Will this do the
job that the Oracle MultiProtocol Interchange is intended to do?
A. No. Protocol converters are also generally specific to two protocols and
are highly application specific, converting the functions performed by
one protocol into similar functions performed by another protocol. They
are generally used for terminal emulation, as they operate at low levels
within the communications stack. In contrast, the Oracle MultiProtocol
Interchange does not perform protocol conversion, but merely forwards the
data stream, so protocol incompatibilities are overcome. A protocol
converter will not perform the tasks that the Oracle MultiProtocol
Interchange can perform.
Q. My customer mentions network bridges. What have they got to do with the
Oracle MultiProtocol Interchange?
A. A bridge is a piece of hardware which connects two different types of
physical network media together. This enables protocols to run over
multiple different physical network media. The Oracle MultiProtocol
Interchange works at a higher level than a bridge, and does not concern
itself with the physical network media.
Q. Does the Oracle MultiProtocol Interchange work with RDBMS V6?
A. As SQL*Net V2 is not available with Oracle RDBMS V6, you need Oracle7
databases and Oracle7-based tools running SQL*Net V2 in order to take
advantage of the Oracle MultiProtocol Interchange.
Q. Then how do I handle migration from SQL*Net V1 to SQL*Net V2?
A. Migration is handled by installing SQL*Net V1 and V2 simultaneously on the
server. This allows both V1 and V2 clients to connect to the server.
You can then migrate your clients when it is convenient. Clients can also
support SQL*Net V1 and V2 simultaneously, with the version to be used
being chosen on a per-connection basis. This enables clients to continue
to access V1-only servers as well as the V2-enabled servers. Clients using
SQL*Net V2 will also be able to use the Oracle MultiProtocol Interchange to
connect to servers running on different protocols.
Q. Are the Oracle Protocol Adapters that I use on my client and server the
same as those used in the Oracle MultiProtocol Interchange?
A. Yes, they are, but each Oracle Protocol Adapter is certified separately
for use in client/server software and the Oracle MultiProtocol Interchange.
This is because the Oracle MultiProtocol Interchange uses the Oracle
Protocol Adapters in a slightly different way than that of client/server
Protocol Adapters.
Q. Can I use all the Oracle Protocol Adapters available on a platform in the
Oracle MultiProtocol Interchange?
A. No. As the Oracle MultiProtocol Interchange is a critical piece of
network software, each Protocol Adapter on a given platform will be
released with or without support for the Oracle MultiProtocol Interchange.
Do not use Protocol Adapters in the Oracle MultiProtocol Interchange unless
they have been certified as supported. Protocols Adapters are only supported
in the Oracle MultiProtocol Interchange when they have passed a series of
stringent integration tests - these tests are performed because the
Oracle MultiProtocol Interchange exerts greater demands on a protocol than
normal client and server software. Oracle Network Products Division
provides a regular matrix of supported protocols and further information is
available from the INFO mail accounts such as INFONCR and INFOPC.
Q. How many Oracle Protocol Adapters can the Oracle MultiProtocol Interchange
support?
A. Provided that the Oracle Protocol Adapters are certified for use with the
Oracle MultiProtocol Interchange, it can support as many as you like. The
major benefit of the Oracle MultiProtocol Interchange is that it is not
constrained to specific protocol-protocol connectivity. Every protocol
supported can be used in any combination.
Q. What can I expect in terms of performance when I use the Oracle
MultiProtocol Interchange?
A. This varies depending on platform, protocol and application. You should
expect that connection establishment times will be longer when going
through two or more protocols although the choice of protocol will
determine how much longer. Once the connection is established, performance
degradation over a single protocol connection is roughly about 5-10%. This
figure shows that the Oracle MultiProtocol Interchange provides an
economical alternative to multiple protocol support on clients and servers
without major performance issues. Oracle Network Products Division has
provided a set of Performance Notes on the Oracle MultiProtocol Interchange
with the SQL*Net V2.0 Sales Kit, and this information is also available
in quickinfo.
Q. Does the Oracle MultiProtocol Interchange give me fault tolerance and
enable me to bypass network failures?
A. It can provide some capabilities in this area. If you have an existing
connection and the section of the network over which the connection is
routed fails, your connection will be lost. If you then attempt to
reestablish the connection, the Oracle MultiProtocol Interchange
may be able to set up your connection between the client and server using
a different route. The ability for it to do this is dependent on
where in the network the failure occurs in relation to the client and the
server.
Q. How does the routing mechanism of SQL*Net V2 work with the Oracle
MultiProtocol Interchange?
A. SQL*Net V2 and the Oracle MultiProtocol Interchange implement a routing
mechanism that is used during connection establishment to determine the
optimum route between client and server. This route is based on the current
SQL*Net configuration files. When a client attempts to initiate a
connection, the routing software in SQL*Net V2 attempts to use the
optimum route, but will fallback to secondary routes if the primary route
is unavailable. In this way, SQL*Net V2 and the Oracle MultiProtocol
Interchange will attempt all possible routes between the client and the
server in order to establish a connection. Failure to establish a
connection will be reported to the client only if all possible routes have
been attempted.
Q. When I am connected through the Oracle MultiProtocol Interchange, will my
connection get rerouted if the machine with the Oracle MultiProtocol
Interchange crashes?
A. No. The routing mechanism described above is only used during connection
establishment. Once you are connected, all data between the client and
the server follow the same route. If the connection between the client and
server is broken either because of network, hardware or software failure,
SQL*Net V2 on the client side will report that the connection has
been disconnected. If the client side then tries to re-connect, the routing
software in SQL*Net V2 and the Oracle MultiProtocol Interchange will attempt
to use all possible routes between client and server in order to establish
the connection. This may mean that the connection goes a different route
from the previous connection in order to bypass failures.
Q. How does my client software know that it is using the Oracle MultiProtocol
Interchange?
A. The client and server are unaware of the use of Oracle MultiProtocol
Interchanges in a connection, and the actual route taken between the client
and server is transparent.
Q. How complex is the Oracle MultiProtocol Interchange to configure?
A. SQL*Net Version 2 is provided with a configuration tool which creates the
Oracle MultiProtocol Interchange configuration files. This tool is
simple to use and creates error free configurations. You should not
attempt to create the configuration files for SQL*Net or the Oracle
MultiProtocol Interchange by hand as this method is not supported by
Oracle. Future releases of SQL*Net will provide configuration migration
tools which only work on configurations created with the configuration tools.
Q. Does the Oracle MultiProtocol Interchange need to be on a standalone
machine?
A. No. The Oracle MultiProtocol Interchange is a piece of software that
can run on the same machine that you also run servers and/or clients. It
is very flexible and does not use all your machine resources. The
choice as to where you install it merely determined by finding a machine
that supports the Oracle MultiProtocol Interchange and has the appropriate
hardware and software to handle the required protocols. You should consider
a couple of points, however:
. Don't install it on a machine that will be constantly rebooted, or on
a machine where you do software development that may crash the machine.
If the machine crashes or is rebooted, all your connections through the
Oracle MultiProtocol Interchange will be lost!
. Consider the number of concurrent connections you intend to run through
the Oracle MultiProtocol Interchange. If you will have a lot of
concurrent connections, don't install the Oracle MultiProtocol Interchange
on a machine that also has to support a lot of client or server
connections as well, because the underlying protocol resources may be
exhausted.
Q. Will the Oracle MultiProtocol Interchange solve all my heterogeneous
network connectivity issues for Oracle clients and servers?
A. The Oracle MultiProtocol Interchange is a way of solving certain network
connectivity issues between Oracle clients and servers, but it is not
the only option. You could also consider installing more protocol
support on the client and/or server side in order to overcome the
protocol barriers, although this may be prohibitive if you have a large
client population in your network. Another solution may be to use database
links in an intermediate server which supports multiple protocols, although
this may have an affect on performance. Overall, the Oracle MultiProtocol
Interchange can be considered an economical solution to some heterogeneous
network connectivity issues.
Q. How many connections can an Oracle MultiProtocol Interchange support
concurrently at an adequate level of performance?
A. It depends on the platform and protocols used as well as the types of
application using it. Some platforms or protocols can only support
a limited number of open connections simultaneously. Also, some types
of application generate a lot of network traffic which will effectively
limit the number of supportable concurrent connections that can run with
adequate response time. In other words, there is no single answer. Oracle
Network Products Division is working on Sizing and Performance metrics
for the Oracle MultiProtocol Interchange at the present time - watch this
space for more information soon.
Q. When should I sell the Oracle MultiProtocol Interchange as a connectivity
solution?
A. Ask the following questions:
- Are there client applications in the customer's network that cannot get
access to the server due to protocol barriers?
- Have all other potential solutions and their cost/benefits been
considered? For example, has it been determined that installing further
Protocol Adapters on the server side is uneconomical or will not solve
the problem? Also, is it necessary to use a different protocol on the
client side from the the server side in the first place? You should
also check availability of the necessary Protocol Adapters for each
platform you wish to connect together.
- Is there an Oracle MultiProtocol Interchange available that will resolve
the specific protocol-to-protocol connectivity that the customer
requires?
- Does the customer have a machine in their network that will support the
ls about logistics for each site.