Kbase 19004: Progress Behavioral Differences Within a LAN vs. WAN
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
16/10/2008 |
|
Status: Verified
GOAL:
Performance expectations for Progress in a networked environment
GOAL:
How progress networking fits into LAN and WAN environments?
FIX:
This Solution details performance expectations for all versions of Progress in a network environment.
Local Area Networks (LANs) and Wide Area Networks (WANs) can be very different in how they work. There are many protocols and architectures in use. Typically, there are several layers of communication protocols involved, each largely insulated from the others and each adding a bit of overhead in exchange for the benefits provided.
Most WAN's are slower than a corporate LAN because they:
- Cover longer distances
- Use slower transmission media
- Have more overhead due to more protocol layers
- Often go through more routers between destinations
LANS:
Most LANs use the Internet Protocol (IP) datagram protocol over 10 megabit per second Ethernet link (some users have 100 megabit per second Ethernets). Other types of LANs exist (for example, token-ring) but they are not the preferred.
The basic IP datagram protocol provides the foundation on which many other things are built. It is connectionless and unreliable. Packets may be lost.
There are a large number of other protocols that are layered on top of IP. The most important of these is Transmission Control Protocol (TCP), that provides a reliable connection-oriented data stream transport.
Progress uses TCP as well as something called User Datagram Protocol (UDP) for some new features in Version 9.x. Progress layers proprietary client-server message protocol on top of TCP/IP. A TCP/IP stack chops up the message stream into IP packets internally without Progress knowing anything about it.
There are several hundred other protocols that are layered on TCP/IP. Some examples are SMTP and POP for email, FTP for file transfer, HTTP for web servers, Telnet and rlogin for terminal emulation, and many others.
WANS:
Many different WAN architectures and protocols are in use. Two commonly used examples are Point to Point Protocol (PPP), used to provide a link-level protocol over modems, and X.25, which is packet-switching protocol developed for use with timesharing systems and public data networks. X25 is falling out of favor however.
In most WANs, Ethernet is replaced by IP layered over some other protocol, or set of protocols. As a result, anything that is built on IP works with it. The layers under IP have overhead associated with them. When you use IP over something else, the maximum IP packet size can be smaller than it would be on a LAN, and the underlying protocol
could also slice it up further.
Progress Networking:
Progress uses its own client-server protocol over TCP/IP. Progress does not know what underlying link-level mechanism is being used (it could be Ethernet, PPP, or something else). The code behaves exactly the same for LANs and WANs and transmits exactly the same way at the Progress client-server protocol level.
FTP:
The File Transfer Protocol (FTP) is very different from what Progress uses. It is designed to do file transfers efficiently. All the data flows in one direction, often in large quantities.