TeD Models of ATM PNNI Networks |
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Overview |
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What is TeD? |
TeD stands for Telecommunications Description Language.
designed mainly for modeling telecommunicating network
elements and protocols.
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What is PNNI? |
PNNI stands for Private Network to Network Interface. It is an
ATM forum
standard for large-scale ATM networks.
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What is modeled? |
The TeD models of the PNNI includes detailed implementations of
most of the protocol features. These include booting the
network from ground-up, dynamic peer-group detection using the Hello
protocol, topology discovery by PTSE flooding, topology aggregation,
call admission control, call routing, VCC setup and tear-down across
the network between user nodes, VCC setup crankback,
VCC failure codes, periodic update of peer group composition,
actual transfer of data packets/cells over established VCCs and so on.
[More information...]
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Background |
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The PNNI models were one of the first complex models of large-scale networks that were developed using the TeD language. The initial version of the models was developed by Kalyan Perumalla and Matthew Andrews at Bellcore in the summer of 1996. The modeling effort was led by Sandeep Bhatt . Further development has been continued at Georgia Tech by Kalyan Perumalla and Fang Hao . |
Simulation |
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Step | Description |
0 | Agree to the terms of usage. |
1 | Obtain the TeD software ted3.0.tar.Z by email request. |
2 |
zcat ted3.0.tar.Z | tar -xvf - extracts into a directory named TED3.0 |
3 | Type make in TED3.0 directory to build TeD. [More info] |
4 | If you intend to use the Jane graphical interface to execute PNNI simulations, edit TED3.0/JANECLIENT/janeclient.csh to set JDKHOME, SWINGHOME and JANEHOME appropriately (use absolute path names for their values). [More info] |
5 | Obtain the PNNI software pnni2.0.tar.Z by email request. |
6 |
zcat pnni2.0.tar.Z | tar -xvf - extracts into a directory named PNNI2.0 |
7 | Goto the PNNI2.0/SRC directory. Edit Makefile to set TEDINSTALLDIR to the directory TED3.0 created in step 2. |
8 | Type make in PNNI2.0/SRC to build PNNI. The executable will be OBJ/ARCH/runmodel, where ARCH is the architecture code of your machine. |
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Execute OBJ/ARCH/runmodel 1 300 to run the default network on 1 processor for 300 units of simulated time. |
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To use the Jane graphical interface:
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Large configurations of the PNNI network models have been simulated in parallel, with significant execution time speedup. See the report on simulation performance .
It is recommended that you first run the simulation on one processor, and consider running in parallel only after you have successfully simulated your network on one processor without any problems. To run on multiple processors of a shared-memory processor, just specify the number of parameters on the command-line argument, as with any TeD application.
Node-to-Processor Mapping for Parallel Simulation |
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The following mapping schemes are incorporated into the PNNI models,
from which the most suitable one should be selected depending upon
the particular network size, configuration and behavior. Assume that
P is the number of processors, and n is the number of physical PNNI
network nodes.
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What is Modeled? |
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Feature | Description | Reference |
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Network boot-up | The network nodes start with no global information, empty topology database, and no peer group leaders. | network.ted |
Dynamic peer group detection | The network nodes discover the neighbors via the Hello protocol, and form peer groups. | pnnitopo.ted |
Topology discovery | The network nodes discover (their view of) the network topology dynamically using the PTSE flooding mechanism, and update their topology databases. | pnnitopo.ted |
Topology aggregation | Peer group leaders aggregate their group's topology. Multiple aggregation methods are supported, from which one can be selected before simulation, and it is easy to incorporate other methods. | pnnitopo.ted |
Peer group election | Election of a peer group leader is modeled simply via configuration. Each PNNI node is assigned a PGL capability level. A PGL capability of a node is the number of (contiguous) levels in the PGL hierarchy at which the node is a group leader. Group leadership is determined via configuration, since PGL election is not implemented in the models. | pnnitopo.ted |
Call admission control | Call admission control algorithms are incorporated in the models. Different methods are supported, such as Competitive On-line; any other algorithm can be easily incorporated. | pnniroute.ted |
Call routing | Calls are routed based on a routing algorithm which can be easily replaced with alternative algorithms. | pnniroute.ted |
VCC setup and tear-down | VCCs can be setup and torn-down at runtime between any two network nodes. The same VCC setup mechanism is used both for setting up communication paths among peer group leaders as well as for VCCs between any network user nodes. In the current model, there is one user node attached to each network node. | pnnivcc.ted, uniclient.ted |
VCC setup crankback | Crankback is implemented by which multiple alternative routes are explored whenever routing along some paths is unsuccessful. | pnniroute.ted |
VCC failure codes | In case a VCC setup fails, the node that initiated the VCC connection is informed of the exact reason for failure. | pnniroute.ted, pnniuser.ted |
Data transfer (packets/cells) | Once a VCC is setup, actual data packets can be transmitted over the VCC. | pnniuser.ted |
Frequently Asked Questions |
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Q1: When I run the PNNI models, I notice messages such as "...VCC connection failed...retrying...". Does it indicate a problem in the simulation? |
Such messages are normal towards the beginning of the simulation, especially while the network is still booting up. What is happening is that some peer group leaders (PGLs) come into existence and initiate VCC connections to the rest of the PGLs in their group. Since the network is not completely setup initially, it is possible for certain connections to fail, in which case the PGLs retry their VCC setup. Note that the messages should indicate that there is no path to the peer as the reason of failure. If you see any other reason, it may indicate there is some other problem in the simulation. |
Q2: Is there a runtime visualization of the network activity as the simulation is progressing? |
Yes, a runtime visualization of the PNNI network hierarchy, and with some traffic behavior animation is incorporated in the latest version fo the PNNI extension of Jane. The Jane graphical interface, which provides a default view of the TeD entity tree information, has been enhanced to include PNNI-specific animations. |
Q3: Where can I get more help/information? |
This document is periodically updated with more information and answers over time. Check out the latest version. Or, send questions via email, or post a question to the TeD users mailing list. |
Distribution List |
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PNNI models have been distributed to researchers at the following institutions upon their request.
AT&T Research | Bellcore | Bell Labs, Lucent Technologies |
BT Labs | Cooperative Systems | ATRI, Curtin Univ. of Tech. |
Georgia Tech | Fondazione Ugo Bordoni, Italy | University of Kent |
National Institute of Standards and Technology | Israel Institute of Technology | [and several others] |
Copyright and Disclaimers |
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The PNNI software is released under the same terms, conditions and disclaimers as the TeD software. |
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Modules | Authors |
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PNNI Core | Perumalla and Andrews |
Crankback | Hao |
Kalyan Perumalla,
20 March 1999
Last updated 15 July 1999