Proxim Tsunami Multipoint Version 2.0 User manual

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Reference Manual
Tsunami Multipoint Version 2.0
P/N 63182v2r1
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Tsunami Multipoint Version 2.0 Reference Manual
Second Edition, December 2003
Copyright and Service Marks
Copyright © 2003 by Proxim Corporation. All rights reserved. No part of this manual may be reproduced without prior
written permission from Proxim Corporation.
The information contained in this manual is subject to change without notice. Proxim Corporation shall not be liable for
errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use
of this manual or equipment supplied with this manual. Proxim Corporation makes no warranty of any kind with regard to
this manual or any equipment supplied with this manual, including, but not limited to, the implied warranties of
merchantability and fitness for a particular purpose.
Tsunami™ is a registered product of Proxim Corporation.
Windowsis a registered product of Microsoft Inc.
Other names are trademarks of their owners.
Y2K (Year 2000 Issue): All software supplied by and for Proxim Corporation products adhere to the four-(4) digit year
nomenclature as required for Year 2000 compliance.
Regulatory Notice
This equipment has been tested and found to comply with the limits for a class B digital device, pursuant to Part 15 of the
FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential
installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in
accordance with the instructions, may cause harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to
radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try
to correct the interference by one or more of the following measures:
Reorient or relocate the receiving antenna.
Increase the separation between the equipment and receiver.
Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
Consult the dealer or an experienced radio/TV technician for help.
Shielded cables and I/O cords must be used for this equipment to comply with the relevant FCC regulations.
Changes or modifications not expressly approved in writing by Proxim Corporation may void the user's authority to
operate this equipment.
This device complies with RSS-210 of Industry Canada. Operation is subject to the following two conditions: (1) this
device may not cause interference, and (2) this device must accept any interference, including interference that may
cause undesired operation of the device.
WARNING! This device must be professionally installed!
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Tsunami Multipoint Version 2.0 Reference Manual
Contents
About Tsunami Multipoint..........................................................................................................................................5
Chapter 1. System Overview.....................................................................................................................................6
System Overview and Radio Considerations.........................................................................................................6
Packet Routing Modes: IP Routing and Bridging ................................................................................................14
Wireline Interface.................................................................................................................................................15
VoIP Support .......................................................................................................................................................16
GPS Receiver ......................................................................................................................................................16
Base Station Configuration Software and Subscriber Utility ................................................................................16
Chapter 2. Ethernet (MAC) Bridging Mode ............................................................................................................17
MAC Bridging Filtering .........................................................................................................................................17
Static Entries........................................................................................................................................................18
Limitations of the Bridging Mode..........................................................................................................................18
VLAN Switching – The PMP Implementation.......................................................................................................19
SU VLAN Filtering................................................................................................................................................22
Chapter 3. IP Routing Mode ....................................................................................................................................25
ARP Tables..........................................................................................................................................................26
Access Modes .....................................................................................................................................................27
Wireless Link Packets Destined for Local Subnet IP Addresses .........................................................................28
Wireless Link Packets Destined for Other Than Local Subnet: RIP Disabled.....................................................28
IP Routing Deployment with RIP Disabled...........................................................................................................29
Packet Routing and RIP.......................................................................................................................................32
Routing Mode Features Not Supported ...............................................................................................................37
Chapter 4. Active Interference Rejection ...............................................................................................................38
Overview..............................................................................................................................................................38
Interference Rejection Technologies ...................................................................................................................39
Planning Ahead with Tsunami Multipoint .............................................................................................................40
Technical Fundamentals......................................................................................................................................41
We improve, at all modulation modes, the carrier-to-interference ratio by 22 dB.Operation................................42
Operation .............................................................................................................................................................43
Interference Rejection Command Summary ........................................................................................................46
Chapter 5. Base Station Configuration Software and Subscriber Utility ............................................................47
System Requirements..........................................................................................................................................47
Removing the Previous BSU Console Version ....................................................................................................48
Installing Configuration Software Version 2.0 ......................................................................................................48
Multi-BSU Configuration Software Version 2.0 ...................................................................................................50
Base Station Configuration Software Version 2.0 ...............................................................................................53
Subscriber Utility Software...................................................................................................................................54
SU Utility Operation .............................................................................................................................................55
Using the Subscriber Utility for Antenna Pointing ................................................................................................59
Chapter 6. Advanced Configuration Options ........................................................................................................61
Multi-Sector Mode................................................................................................................................................61
Setting Ethernet Frame Type Filtering (EtherMode) ............................................................................................67
Configuring for IP Multicasting .............................................................................................................................67
Voice over IP (VoIP) ............................................................................................................................................67
Choosing the Priority Connection Bandwidth.......................................................................................................68
Chapter 7. Command Reference.............................................................................................................................76
BSU Commands for Configuring and Monitoring the BSU...................................................................................76
BSU Commands for Configuring and Monitoring the SU .....................................................................................77
SU Commands for Configuring and Monitoring the SU........................................................................................77
Command Format................................................................................................................................................77
Valid IP/Gateway Addresses ...............................................................................................................................79
Base Station Configuration Commands ...............................................................................................................79
BSU Commands for Configuring the SU’s from the BSU.....................................................................................96
SU Commands for Configuring and Monitoring SUs..........................................................................................104
Appendix A. Troubleshooting...............................................................................................................................111
Troubleshooting Data Stream Errors and Interference ......................................................................................112
Counteracting and Evaluating Interference........................................................................................................113
Appendix B. Technical Specifications .................................................................................................................114
Contents 3
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Tsunami Multipoint Version 2.0 Reference Manual
Burst-Rate Limit .................................................................................................................................................114
Downlink/Uplink Throughput ..............................................................................................................................114
Frequency Plans................................................................................................................................................114
Tx Power............................................................................................................................................................114
Antenna .............................................................................................................................................................115
Receiver Sensitivity ...........................................................................................................................................115
Maximum Distance Between Base Station and Subscriber Unit........................................................................115
System...............................................................................................................................................................115
Standards Compliance and Interfaces ...............................................................................................................116
Configuration and Management.........................................................................................................................116
Power/Environment Safety ................................................................................................................................116
Physical Dimension ...........................................................................................................................................117
Installation Details..............................................................................................................................................117
Optional Accessories .........................................................................................................................................117
Tsunami Multipoint Version 2.0 BSU Models.....................................................................................................117
Tsunami Multipoint Version 2.0 SU Models .......................................................................................................118
Declaration of Conformity ..................................................................................................................................118
Appendix C. Technical Support............................................................................................................................119
Warranty ..................................................................................................................................................................120
1 YEAR LIMITED EQUIPMENT WARRANTY ...................................................................................................120
Figures
Figure 1. Wide Coverage, High Capacity TCP/IP Network ........................................................................ 6
Figure 2. Single Frame ............................................................................................................................... 8
Figure 3. Model of the PMP Network ....................................................................................................... 14
Figure 4. SU Filters in Bridging Mode ...................................................................................................... 17
Figure 5. PMP VLAN Implementation ...................................................................................................... 21
Figure 6. VLAN Tagging Support in PMP Network ..................................................................................22
Figure 7. Multiple VLAN IDs at an Individual SU...................................................................................... 23
Figure 8. BSU/SU Connection by Switch ................................................................................................. 25
Figure 9. Proxy for Remote Devices Residing in the Same Subnet......................................................... 29
Figure 10. Network Diagram Example 1 Configuration Settings............................................................. 31
Figure 11. Sample Campus Networking Layout....................................................................................... 32
Figure 12. Sector Acting as a Virtual Router in IP Routing Mode ............................................................ 33
Figure 13. Network Diagram – Example 2 ............................................................................................... 36
Figure 14. Rejection to Linear Polarized Interference.............................................................................. 41
Figure 15. intlog Example......................................................................................................................... 45
Figure 16. Multi-BSU Console .................................................................................................................. 63
Figure 17. Connect To Setup Window ..................................................................................................... 64
Figure 18. Fresnel Zones ....................................................................................................................... 115
Tables
Table 1 Maximum Burst Rates ................................................................................................................... 7
Table 2 Expected Ethernet Frame Throughputs (Aggregate) .................................................................... 8
Table 3 Expected Standard and Optional FTP Performance..................................................................... 9
Table 4 Standard and Optional Frame Structure ....................................................................................... 9
Table 5 Frame Durations............................................................................................................................ 9
Table 6 Center Channel Frequencies ...................................................................................................... 11
Table 7 Network Diagram Example 2 Configuration Settings .................................................................. 36
Table 8 Carrier to Interference Improvement Using A.I.R. .......................................................................42
Table 9 Required VoIP Data Rates for Various Codecs .......................................................................... 69
Table 10 Selection for T1/E1 .................................................................................................................... 70
Table 11 Maximum VoIP Connections per SU by VoIP Bandwidth ......................................................... 72
Table 12 Maximum VoIP Connections per SU due to Packet Rate Limitations....................................... 73
Table 13 Maximum Number of Simultaneous Calls per BSU .................................................................. 74
Table 14 Max Simultaneous Calls per BSU due to Packet Processing Limitations................................. 75
Contents 4
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Tsunami Multipoint Version 2.0 Reference Manual
About Tsunami Multipoint
Tsunami Multipoint is a point-to-multipoint outdoor wireless system offering a high capacity alternative to
wired data networks.
Using IP packet radio transmitters, standard Ethernet interfaces, and an easy-to-deploy design, the Tsunami
Multipoint system enables high-speed network connections to multiple Ethernet switches, routers or PCs
from a single location. With Tsunami Multipoint, you can avoid the delays and costs associated with wired
connections such as DSL, cable modems, and leased T1/E1 lines.
Tsunami Multipoint systems consist of one or more Subscriber Units (SU) that communicates with a Base
Station Unit (BSU) to provide high-performance wireless network connections.
The following documents comprise the Tsunami Multipoint documentation set.
▪The Tsunami Multipoint BSU Quick Install provides just enough information for the experienced
professional to install the Tsunami Multipoint BSU.
▪The Tsunami Multipoint SU Quick Install provides just enough information for the experienced
professional to install the Tsunami Multipoint SU.
▪The Tsunami Multipoint Installation Guide provides detailed installation information for the less
experienced professional to install and initially configure the Tsunami Multipoint system. If you are
uncertain about any of the procedures in the Quick Install, refer to this document on the Tsunami
Multipoint CD.
▪The Tsunami Multipoint Reference Manual provides conceptual, advanced configuration, and command
reference information about the Tsunami Multipoint system. See the Reference Manual for information
about:
º Routing modes
º Active Interference Rejection (A.I.R.)
º Priority Queuing
º Advanced Configuration Options
º Command Reference
º Troubleshooting
About Tsunami Multipoint 5
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Tsunami Multipoint Version 2.0 Reference Manual
Chapter 1. System Overview
A Tsunami Multipoint system is comprised of one-to-six Base Station Units (BSUs) and associated
Subscriber Units (SUs) that comprise a cell. Each BSU communicates with its associated SUs in its sector.
Considered alone, the BSUs and SUs essentially function as radios. When configured together and attached
to network segments separated over some distance with clear line of sight, they provide a wide-coverage,
high-capacity TCP/IP network that transfers IP traffic between the cell hub and its multiple SUs.
Over this network, users can support services, such as the following (as well as other applications):
▪Providing network connectivity between buildings or campuses (Virtual Private Network (VPN) scenario)
▪Establishing high-speed connections between Internet Service Providers (ISPs) and their customers
▪Providing surveillance over remote sites
Figure 1. Wide Coverage, High Capacity TCP/IP Network
Note: Uplink and downlink are also referred as inbound (IB) and outbound (OB), respectively,
throughout this document.
SYSTEM OVERVIEW AND RADIO CONSIDERATIONS
Communication
Each SU communicates with a BSU in a coordinated manner so that all SUs associated with the BSU have
an equal amount of time to coordinate their data needs in both the uplink and downlink directions. The
Tsunami Multipoint system uses a master-slave relationship with the BSU being the master and the SUs
being the slaves. The BSU broadcasts to the SUs and all SUs capable of communicating at the BSU burst
rate tune in. When an SU requires bandwidth, it makes a request to the BSU and the BSU, in turn, assigns a
time period for the SU to transmit during the uplink portion of the frame. This bandwidth request and
scheduling is handled on a frame-by-frame basis giving users the impression that they are in constant
communication with their BSUs.
Chapter 1. System Overview 6
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Tsunami Multipoint Version 2.0 Reference Manual
A single cell of six 60-degree sectors can communicate in all directions (360°). Each sector, consisting of a
single BSU and associated SUs (a single BSU can communicate with up to 1,023 SUs ), can be configured
to communicate at a maximum burst rate of 60 Mbps. Consequently, a single cell consisting of six BSUs has
a maximum throughput of 360 Mbps.
Data Rate
SUs are available in versions with maximum burst rates of 60 Mbps and 20 Mbps. BSUs are available in 60
Mbps or 20 Mbps versions. These data rates are achieved by using a combination of different modulation
and coding schemes. A BSU or SU can operate at its maximum burst rate or at any lower burst rate. For
example, a 60 Mbps BSU can be configured to operate at 20 Mbps, 30 Mbps, 40 Mbps, or 60 Mbps. If set
to operate at 20 Mbps, all SUs can communicate with it . A 60 Mbps BSU configured to 40 Mbps can
communicate with SUs capable of 40 Mbps or faster, however, they could not communicate with SUs having
a maximum burst rate of 20 Mbps.
Table 1 Maximum Burst Rates
Product Burst-Rate Limit Also Supports
Base Station Unit 60 Mbps
20 Mbps
20-40 Mbps burst rates
Subscriber Unit 60 Mbps
20 Mbps
20-40 Mbps burst rates
Note: This table describes the product upgrade/compatibility policy. The BSU and SU must use the same
burst rate within a sector to achieve wireless communication. If an SU cannot operate at the speed
at which the BSU is broadcasting, it displays a link status of “outbound detected.”
Partitioning Uplink and Downlink Data Rates
The Tsunami Multipoint system operates using a frame-structured Time Division Duplexing (TDD). TDD
means both the uplink and downlink operate on the same frequency at different times. At the beginning of a
frame, data is broadcast from the BSU to all the SUs in a sector. After the downlink completes, the SUs
transmit data on the uplink to the BSU. All the SUs share the uplink and transmit at different times. A single
frame is shown in the following figure:
Chapter 1. System Overview 7
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Tsunami Multipoint Version 2.0 Reference Manual
Rx-to-Tx
Guard
Interval
Tx-to-Rx
Guard
Interval
Transmit
Portion
of
Frame
Receive
Portion
of
Frame
Single
Frame
Slot 0
Slot 1 Slot 2
Slot N-1
. . . .
Slot N
Slot N+1
Slot M
. . . .
Figure 2. Single Frame
The BSU determines which SU is to transmit at what instant in time. The entire frame consists of a fixed
number of slots (the exact number depends upon the data rate used (such as 30 Mbps, 40 Mbps, or 60
Mbps). You can use the firstInboundSlot command (on page 81) to set the ratio of downlink-to-uplink
slots.
When setting the ratio, be aware that:
▪Not all ratios are useable (see “firstInboundSlot” on page 81).
▪There is a possibility of BSU-to-BSU interference if different sectors have different ratios of uplink to
downlink traffic. All co-located BSUs should have the same ratio.
▪The uplink has slightly lower capacity than the downlink for the same number of assigned slots due to
link overhead. The following table provides expected throughputs for symmetrically configured links
(same number of uplink and downlink slots), measured at level 2.
Table 2 Expected Ethernet Frame Throughputs (Aggregate)
Burst Rate (Mbps) D/L Throughput (Mbps) Uplink Throughput (Mbps)
20 9 8
30 13.5 12
40 18 16
60 27 24
Chapter 1. System Overview 8
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Tsunami Multipoint Version 2.0 Reference Manual
Table 3 Expected Standard and Optional FTP Performance
Standard Optional
Burst Rate
Get, Mbps Put, Mbps Get, Mbps Put, Mbps
20 Mbps 9.541 8.375 8.945 7.850
30 14.3 10.0 11.8 12.3
40 19.0 10.0 17.8 14.5
60 28.4 9.975 26.8 15.1
Frame Duration Options
The default frame duration is 7.5 msec for all modulation types (burst rates).
Table 4 Standard and Optional Frame Structure
Standard Optional
Burst Rate
Slots/Frame Length, ms Slots/Frame Length, ms
20 Mbps 8 7.5 8 8
30 12 7.5 8 6
40 16 7.5 8 4
60 24 7.5 12 4
The product also has an optional frame duration mode that can be enabled with the setFrameDuration
command. Besides its modified frame duration, the Optional Mode uses longer guard intervals.
The following table contains the frame durations for this optional mode (as a function of burst rate).
Table 5 Frame Durations
Burst Rate Frame Duration in Optional Mode (msec)
20 8
30 6.024
40 4
60 4
Chapter 1. System Overview 9
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Tsunami Multipoint Version 2.0 Reference Manual
The advantages of the Optional Mode are:
Longer maximum range
The maximum range (maximum distance between a BSU and SU) is determined by a number of factors
including modulation type, transmit power, antenna gain, required fade margin, and length of guard
interval. In the Standard mode the guard interval limits the maximum range to 6 miles. Consequently,
even if the link budget would allow operation at greater distances (for example, a line-of-sight link with
high-gain antennas), the maximum range is limited to 6 miles. The Optional mode increases this limit to
15 miles. Consequently, if the link budget allows operation at that distance, the framing structure will not
limit it.
Faster FTP throughputs in burst rates greater than 20 Mbps
The latency at any given point in time is determined by system loading at that time. However, reducing
the frame duration also reduces the average latency. A reduced latency link results in an increase in
FTP throughput.
The disadvantages of using the optional frame duration mode are:
Less efficient
The reduction in frame duration coupled with the increase in guard duration results in a link that is slightly
less efficient than the standard frame duration mode.
A.I.R. BSU’s do not work in the optional frame duration mode
Console commands to enable the Optional Frame Mode are ignored when the BSU is configured for
interference rejection. The BSU notifies the operator with the following console message: “Optional
Frame Mode is not supported in Active Interference Rejection Mode”. Similarly, console commands to
enable interference rejection while in the Optional Frame Mode are ignored and result in the console
warning message: “Active Interference Rejection Mode is not supported when in the Optional Frame
Mode.”
Interference in co-located BSUs
When multiple BSUs are operating at the same site, there is the potential for them to interfere with each
other. For example, if a single tower has multiple sectors deployed and one BSU is transmitting while
another BSU on the tower is receiving, there is a good possibility that the transmitting BSU will cause
enough interference to severely degrade the performance of the receiving BSU. This can happen even
when the BSUs are operating in different frequency bands.
One solution is to shield the BSU with electromagnetic radiation-absorbing material. Another solution is
to deploy the BSUs far enough apart to reduce the interference to an acceptable level. However, even
these solutions may not be enough to mitigate the interference.
Each Tsunami Multipoint BSU can synchronize its timing using GPS. In this mode, all BSUs start their
frames at the same time (within some allowable tolerance). This way, one BSU is never listening while
another BSU is transmitting. For this synchronization to work, all the BSU’s must use the same frame
duration and have the same ratio of uplink to downlink slots. This is easily accomplished using the
standard frame duration mode. However, in the Optional Mode, due to the varying frame durations, it
would be impossible to have different BSU’s operating using different burst rates and still maintain BSU-
to-BSU timing synchronization.
Chapter 1. System Overview 10
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Tsunami Multipoint Version 2.0 Reference Manual
Frequency Band
The Tsunami Multipoint operates in the 5.725 to 5.825 Unlicensed Frequency band. Within this band, you
can select one of three channel plans: 4, 5, or 6. The following table contains the center frequencies for all
of the channels in each of these plans.
Table 6 Center Channel Frequencies
Center Frequency (MHz)
Channel
4-Channel Plan 5-Channel Plan 6-Channel Plan
A 5725.86 5740.40 5740.40
B 5764.61 5757.69 5754.23
C 5725.36 5774.98 5768.07
D 5806.11 5792.28 5781.90
E N/A 5809.57 5795.73
F N/A N/A 5809.57
The SU must be configured to be in the same frequency channel plan as the BSU if it is to enter the network.
However, once the frequency channel plan is configured at the SU, it can be set to automatically search all
available channels to find a BSU.
Transmit Power and Power Control
You can use the txPowerLevel command (page 94) to set the BSU transmit power from between 6 and 17
dBm (at the input to the transmit antenna). You can use the txPowerAutoEnable command (page 94) to
set the BSU to automatically start transmitting whenever it is restarted or power is cycled.
The SUs automatically adjust their transmit power to ensure that the signals from all SUs arrive at the BSU at
the same power level. This minimizes self-interference that can occur in a sector.
The IPC should never be set lower than 7 dB or higher than 13 dB at 60 dB, or higher than 25 at all other
modulations. The normal value is 10 dB. For most users, nominal settings suffice. Higher IPC settings
increase the link margin, but may make it impossible for SUs at the sector edge to successfully communicate
with the BSU. Lower settings result in the greatest range, but may have a slightly higher BER (bit error rate).
You can set the margin with the IPC command on page 84.
Network Entry and SU Monitoring
This section describes the process an SU follows when it is first turned on and must enter the network.
Downlink Synchronization
Immediately after being powered-up, the SU begins looking for the downlink signal. It cycles through all
of the different frequency channels in the configured frequency plan looking for a valid signal. (If the SU
has been configured to search over a single frequency, it does not search the rest of the frequencies in
the plan.) Once it verifies that it has found a valid signal, the SU then synchronizes its timing and
frequency to the downlink.
Chapter 1. System Overview 11
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Tsunami Multipoint Version 2.0 Reference Manual
Ranging and Power Adjustment
Tsunami Multipoint uses Time Division Multiple Access (TDMA) on the uplink to let multiple users use
the single uplink. In TDMA different SUs are assigned different time sub-slots1to transmit their signals.
A time sub-slot is referenced to the BSU; that is, the SU is told when its signal must arrive at the BSU.
The reason for referencing the time slots to the BSU is to keep the signals of different SUs from
overlapping, even when they are at vastly different ranges. It takes a longer time for the signal at the
longest range to arrive at the BSU compared to a signal at the shortest range. For example, assuming
that the minimum range is 50 meters and the maximum range is 10 km, it would take the signal at 10 km
approximately 33 microseconds longer to reach the BSU than the signal at 50 m. In some cases, a sub-
slot lasts only 9.75 microseconds.
Once the SU has obtained downlink synchronization, it goes through a ranging process. In the ranging
process, the SU determines when it must transmit to be received at the BSU at a given instant in time. It
then uses this information to determine when to begin its transmission to arrive at the BSU in its allotted
time slot.
In addition to ranging, the SU must determine at what power level to transmit. Once again the path loss
for an SU at maximum range would be much greater than the path loss for a subscriber unit at minimum
range. If these two units are assigned adjacent TDMA slots, this power differential could lead to errors in
the received signal. To avoid this, each SU adjusts it power so that it is received at the BSU at a given
level (determined by the BSU) regardless of range.
Network Entry and Registration
Once the SU has synchronized to the downlink and completed the ranging and power adjustment
process, it is ready to communicate with the BSU. Before it starts to transmit data, it first must register.
Registration is by invitation only. The BSU periodically invites any SU in its database to register. When
the SU receives this invitation, it transmits a response; if the BSU determines that it is a valid SU, it is
allowed to enter the network. At this point, it is assigned an ID (SU id) that is used in the bandwidth
request and assignment process. Net entry is now complete. If the SU is not determined valid by the
BSU, the SU displays the following console message:
998 SU authentication fails, please check Base Station database.
Loss-of-Link
The SU can lose the link if the BSU loses power or experiences a deep fade (the path loss momentarily
becomes excessive). The SU monitors the downlink control message, which is sent once a frame, to
verify that it has not lost the link. If it does not see this control message for a pre-determined number of
consecutive frames, the SU declares a loss-of-lock condition and attempts to re-acquire the network.
Re-acquisition After Loss-of-Link
When the SU has detected that it has lost the link, it immediately begins searching for the downlink. It
initially searches the same frequency it was using when it lost the link. If it does not find the downlink
within ten minutes, it begins searching all frequencies for the downlink.
1The use of the word sub-slot should not be confused with the slotted nature of the downlink and uplink. A
single uplink/downlink slot is divided into 32 sub-slots. This way, up to 32 different SUs can transmit in a
single uplink slot.
Chapter 1. System Overview 12
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Note: Waiting ten minutes before searching other frequencies was chosen for the following reason:
A BSU using GPS to synchronize its timing can take close to 10 minutes to resume transmission
after a power cycle. Much of this time is required for the GPS receiver to acquire the four
satellites required to obtain accurate timing information. SUs are allowed to begin searching
other frequencies before a power-cycled BSU can resume transmission. It is possible (even
probable) that an SU that can see multiple BSUs will acquire the downlink of a different BSU (not
the one to which it was originally attached) when its original BSU is power cycled. If it is not in
the new BSU’s database, it simply waits to be polled (it displays an ‘Authorization Failed’
message in the SU utility). This problem could occur whenever a BSU is power cycled (new
code is downloaded). By forcing an SU to search on its last frequency for ten minutes, we
ensure the SU reconnects with the power cycled BSU.
If the SU acquires the downlink on the same frequency, it resumes normal operation with the following
exceptions:
▪When polled, the SU sends a message to the BSU informing it that it has re-entered the network. This
lets the BSU keep track of how often the SU loses lock. Because it sends this message in response to a
poll, the SU actually can transmit data (if it has any) prior to sending this message.
▪When the SU first transmits after the outage, it receives an acknowledgement from the BSU that the
transmission was received. If it does not receive this acknowledgement, the SU retransmits the data.
After a predetermined number of re-transmission failures, the SU assumes there is something wrong
with the uplink and starts the ranging and power adjustment cycle.
If the SU does not acquire the downlink on the same frequency within 10 minutes, it begins searching all
frequencies, looking for the downlink. Once the downlink is acquired, the SU proceeds to the ranging and
power adjustment phase. Entering the network after a loss-of-link and a failure to quickly re-acquire the
downlink on the same frequency is similar to the initial network entry procedure.
Monitoring the SU
Periodically the BSU polls the SU for status information. (The exact timing depends upon the number of
SUs entered in the BSU’s database and ranges from approximately once per second to once per ten
seconds.) Issuing a dspActiveSU command displays all SUs that have recently responded when polled
(dspSU simply displays all the SUs in the BSU database).
When an SU does not respond to consecutive polls, the following message is displayed on the Base Station
Configuration Software console indicating that the SU has dropped from the network (a message also is
displayed on the console when the SU re-enters the network).
999 SUx not responding to poll (where x is the SU ID) message
The dspActiveSU command lets the user know how many times the SU has entered the network since the
last time the BSU was power cycled.
Point-to-Multipoint Network Model
In the Point-to-Multipoint (PMP) network, consider the SU and the BSU as an integrated transmission and
switching medium with physical ports (or access points) that interface to end user devices. Each BSU or SU
represents one such physical port (or access point).
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Data traffic between the BSU and an SU flows as follows:
▪Packets received by an SU are transmitted to the BSU.
▪Packets from all SUs emerge from the BSU as a single data stream. SUs only transmit packets to the
BSU if the packet’s destination address is not local to the SU. Each SU maintains an ARP table to
distinguish between local and other addresses.
▪Downlink packets are received by the BSU and broadcast to all SUs in the sector.
Figure 3. Model of the PMP Network
PACKET ROUTING MODES: IP ROUTING AND BRIDGING
The predominant task of a network is to route packets between devices (most commonly computers).
Packets may have to travel just a few feet over a twisted wire, or they may have to travel thousands of miles
and traverse many networks.
In an IP network, devices typically are assigned two different addresses. The first is the device’s MAC
address and the second is its IP address. The MAC (Ethernet) address is a layer 2 address; the IP address
is a layer 3 address (referring to the OSI seven layer networking model).
Devices that route packets through networks using MAC addresses are called Bridging devices (a switch is
a Bridging device); devices that use layer 3 addresses are called IP Routing devices (a router is a layer 3
device). Although bridging and routing devices both are designed to route packets, there are practical
differences in how they work. The network architecture generally dictates which device to use (although in
many situations, either is acceptable).
Tsunami Multipoint offers two routing modes—IP Routing mode and Ethernet Bridging mode. Tsunami
Multipoint supports one mode at a time per BSU. Proxim recommends Bridging mode for most applications,
as it is the most “plug-and-play” mode and requires little network reconfiguration.
Bridging Mode
In Bridging mode, the Tsunami Multipoint network uses the ARP table to filter packets; each SU can capture
and store up to 8,000 local addresses in its ARP table. Proxim recommends using Bridging mode as it is the
most “plug-and-play” mode and requires little network configuration.
▪A local packet received by the SU on its Ethernet port is filtered through its ARP table before being
transmitted uplink. If the destination MAC address of the received packet belongs to a local drive, the
packet is dropped.
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▪Similarly, any downlink packet received by the SU is filtered through the ARP table before being
transmitted to its local network. If the destination address of the received packet cannot be found in the
ARP table, the packet is dropped.
The downlink filtering operation can be turned off as a configuration option.
In Bridging mode, you can configure up to 16 VLAN filters per SU. In addition to the SU’s own assigned
VLAN ID, each filter defines the range of VLAN IDs of the received VLAN frames that may pass through the
SU in either uplink or downlink direction. In addition, the Tsunami Multipoint network performs VLAN tagging
and un-tagging operations. See “VLAN Switching – The PMP Implementation” on page 19.
You can configure the Tsunami Multipoint product to work in either Ethernet Bridging or IP Routing mode.
IP Routing Mode
In IP Routing mode, each SU or BSU behaves as an IP gateway to its local devices. Normally under this
type of configuration, each SU or BSU occupies a unique, non-overlapping subnet. At the hub, each BSU is
connected to an external router either individually or through a common switch, and serves as an IP gateway
to all subnets that can be directly or indirectly accessed through its SUs.
▪When the RIP option is enabled, the routes are exchanged automatically and updated periodically
between the BSU and the external router. As such, no manual configuration of static routes in the
external router is necessary. The same applies to the SU side when an SU is connected to an external
router.
▪When the RIP option is not enabled, all the routes associated with each BSU must be entered manually
into the external router as static routes.
With the RIP feature enabled, all the BSUs and the external router can share the same subnet and
interconnect through a simple switch. Rather than installing a router with many physical ports, one port for
wireless network access and one port for Internet access are sufficient for network operations.
If Internet access at the BSU side, or SU-to-SU communication within the same BSU, are not required, you
can completely eliminate the external router. For details about IP Routing mode operation, see “Chapter 3.
IP Routing Mode” on page 25.
Note: Only IP packets (Ethertype 0x800) are passed in IP Routing mode.
WIRELINE INTERFACE
Tsunami Multipoint equipment is connected to a WAN or a LAN through a 10/100 Base-T Ethernet
connection. This connection supports speeds of either 10 or 100 Mbps in half- or full-duplex mode. Most
100 Base-T interfaces support auto-negotiation, in which the end points negotiate the speed and duplex of
the link. The default operating mode for the Tsunami Multipoint Ethernet interface is auto-negotiation.
However, auto-negotiation is not as standardized as you may have been led to believe, and it frequently
does not perform as expected. Furthermore, if one side of the link is set to auto-negotiate and the other side
is configured manually, auto-negotiation fails. In this case, the side set to auto-negotiate correctly
determines the link speed but defaults to half duplex. This can lead to duplex mismatch between the two
ends of the link.
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Symptoms of mismatch problems include:
▪Network performance that is considerably lower than it should be
▪Significant errors shown when using the netstat –e command
To alleviate this problem, you can disable the auto-negotiate feature of the BSU/SU and use the setEthernet
command for the BSU and the setSUEthernet command (entered at the BSU to set the SU Ethernet
interface) to manually set the Ethernet interface to the desired mode. Similarly, you should configure the
host attached to the Tsunami Multipoint equipment for manual operation to ensure that both ends of the link
are operating at the same speed and duplex mode.
See “setEthernet command” on page 89 and “setSUEthernet command” on page 100 for more information.
VOIP SUPPORT
Tsunami Multipoint SUs prioritize uplink voice traffic by first separating incoming traffic into voice and data
queues. Traffic can be filtered based on the ToS (Type of Service) byte setting. Data is sent to the voice
queue if its ToS byte falls within the user-selected range. When the SU receives an uplink bandwidth
assignment, it transmits packets in the voice queue first.
In addition to prioritizing the transmission of voice IP traffic, an SU is assigned adequate bandwidth for each
on-going VoIP connection to ensure the voice quality. The total bandwidth assigned to the SU is adjusted
dynamically every 7.5 msec based upon the number of active VoIP connections monitored in the previous
frame. A VoIP connection is taken down if no VoIP traffic is observed for that connection for the pre-defined
period of time. In addition to the guaranteed VoIP bandwidth assignment, an SU is assigned additional
bandwidth for its data traffic on a best-effort basis whenever leftover bandwidth is available.
At this time no priority assignment is given to differing types of downlink traffic. Typically, the downlink has
enough bandwidth to handle all traffic in a timely manner even without specific priority mechanisms. In
addition, because the downlink is a single flow, it is easy to use a third party QoS box.
GPS RECEIVER
Each Tsunami Multipoint BSU includes a GPS with a mechanical-mount GPS antenna. The GPS enables
each Tsunami Multipoint BSU to start transmitting frames of data at the same time as other Tsunami
Multipoint BSUs at the same or adjacent hub sites. This results in Tsunami Multipoint BSUs transmitting and
receiving information at the same time and avoids interference between BSUs. (See “Multi-Sector Mode” on
page 61.)
BASE STATION CONFIGURATION SOFTWARE AND SUBSCRIBER UTILITY
The majority of configuration is done at the BSU using the command line interface (CLI) provided by the
Base Station Configuration Software. At the SU, the Subscriber Utility provides an interface to configure and
monitor the SU. Both software programs run on PCs and communicate with the BSU or SU over their
Ethernet interfaces.
The Tsusnami Multipoint Installation Manual contains information pertaining to installing and running these
utilities.
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Chapter 2. Ethernet (MAC) Bridging Mode
In Ethernet Bridging mode, the PMP network provides a direct physical connection between an SU and its
BSU for the exchange of Ethernet frames between the two units. To conserve wireless bandwidth, the SU
uses some simple hardware and software filtering criteria to prevent traffic destined for a local network from
being sent uplink.
MAC BRIDGING FILTERING
Subscriber Unit (SU)
Local
Traffic
Uplink
Traffic
Downlink
Traffic
ARP
Table
Filter
Hardware
Address Filter
Programmable Filter
Figure 4. SU Filters in Bridging Mode
In the uplink direction (from an SU to its BSU), the filtering works as follows:
▪If the received IP packet’s destination Ethernet address is not in the SU’s hardware table of local
devices, the packet is passed to the software for further filtering; otherwise, it is discarded.
▪The software provides further filtering by matching the destination address with local addresses stored in
its ARP table. If the destination address matches a local address, the packet is discarded. Otherwise, it
is sent on the uplink.
▪Once the packet arrives at the BSU, it is passed through the BSU’s Ethernet port onto the wireline.
In the downlink direction (from a BSU to an SU), the filtering works as follows:
▪If the received packet’s destination is not in the BSU’s hardware table (of local addresses), it is broadcast
on the downlink.
Traffic received at an SU (from the BSU) is further filtered as follows:
▪If the MAC filtering mode has been set to Off using the setSUMACFilter command (on page 101), all
packets received on the downlink at the SU are passed through the Ethernet interface onto the wireline
network.
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▪If the MAC filtering mode is set to on:
º Packets addressed to a broadcast Ethernet address are passed onto the local network.
º For other packets, the SU determines whether the downlink packet’s destination Ethernet address
triggers a “hit” in the filter list. If so, the hardware forwards the packet to software for delivery to the
local network. If the packet’s destination Ethernet address does not register a “hit” in the filter list,
the packet is discarded. A packet registers a “hit” if the SU has seen traffic originating from the
Ethernet address or the address has been entered as static as described in the following section.
Note: In pre-1.3 versions of the Tsunami Multipoint software, MAC filtering was set to off. This meant that
all packets received at the SU on the downlink were passed onto the wireline network.
STATIC ENTRIES
Typically when one host (originating host) attempts to communicate with another host (destination host), it
first sends an ARP to determine the destination host’s address. This ARP is passed because it is addressed
to a broadcast Ethernet address. When the destination host responds, the SU enters the address into its
MAC filter list. This enables subsequent packets to pass through the filter.
Notes: If the packet’s destination Ethernet address does not register a “hit” in the filter list, the packet is
discarded. Whenever the SU sees traffic from a host, it enters it into its MAC filter list, with a 20-
minute time-to-live (TTL).)
In a small number of situations, the originating host knows the destination host’s Ethernet address through
static means (the address was entered statically into the originating host’s ARP table). In this case, the
originating host does not ARP before sending a packet; consequently, the destination host is not in the SU’s
filter list and subsequent packets are discarded. To avoid this problem, you can enter up to five static IP
addresses. The SU discovers the Ethernet addresses associated with these IP addresses and adds them to
the filter list.
LIMITATIONS OF THE BRIDGING MODE
Again, when viewing the PMP network as a multi-port bridge, only a limited bridging function is exhibited. A
true bridge can switch a packet arriving at any port to any other port. For the PMP network to behave
similarly, whatever data received by the BSU from an SU would also need to be broadcast back downlink to
all other SUs associated with the BSU. This is not done.
Note: The current design is driven by security concerns. Conventional bridging cannot be supported
without additional add-on subsystems.
Bridging mode consumes more wireless bandwidth than IP Routing mode. The reasons for this are as
follows:
▪The entire Ethernet frame, including the Ethernet header, is transmitted between the SU and the BSU.
▪All ARP and broadcast packets are transmitted between the SU and BSU. Empirical results have shown
that, generally, Bridging mode consumes more bandwidth than IP Routing mode.
▪Bridging mode does not currently support the spanning tree algorithm.
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VLAN SWITCHING – THE PMP IMPLEMENTATION
VLAN switching is used primarily for segregating LAN traffic based upon a VLAN ID that accompanies a
received VLAN frame. VLAN switching is useful because:
▪It lets network operators partition their LAN segment into closed user groups.
▪It lets a device communicate only with other devices of the same group.
▪Unlike a regular bridge, a VLAN switch can deliver received VLAN frames only to other ports tagged with
the same VLAN ID, thus reducing unwanted network traffic.
VLAN switching is quick and simple from a switching node’s perspective. However, setting up a VLAN
network can be a tedious exercise for the network administrator because most of the end user devices today
(such as PCs) are not VLAN aware.
This forces the network operator to place VLAN switches at critical junctions all over the network so that
VLAN frames can be converted into regular Ethernet frames and vice versa. This can be a complex, time-
consuming, and costly endeavor if proper planning does not take place beforehand.
To address this issue, PMP network provides a built-in VLAN-to-Ethernet conversion capability in the SUs
and BSUs, as illustrated in the following example (Figure 5).
1. In Figure 5, both BSU1 and SU1 are tagged. When SU1 receives a VLAN frame from VLAN SW1, if the
VLAN frame’s ID is not 4 (SU1’s own VLAN ID) or 5-6 (IDs defined in SU1’s filter list), the frame is
dropped. Otherwise, the frame is delivered to BSU1. In the downlink direction, when SU1 receives a
VLAN frame from BSU1, if its VLAN ID is not 4-6, or its destination Ethernet address cannot be located
in SU1’s ARP table, the frame is dropped.
2. BSU2 is untagged which means, regardless of whether SU2 is tagged or not, it passes through either
VLAN or Ethernet frames without conversion, even though the VLAN filtering operation described in step
1 continues to function if VLAN frames are received by SU2.
3. BSU3 is tagged while SU3 is untagged. This means, when SU3 receives an Ethernet frame from PC 7, it
converts the Ethernet frame into a VLAN frame with VLAN ID 7 (SU3’s assigned ID) and passes the
converted frame to BSU3. When SU3 receives a VLAN frame from BSU3, if its VLAN ID is 7 and the
destination address is for PC7, the frame is converted into a regular Ethernet frame and given to PC7.
Any other VLAN frames received by SU3 are dropped.
4. The BS console can talk to all BSUs because they are all associated with VLAN 5.
5. Only PC1 can access Router 1 for Internet access because only they share the same VLAN ID.
General Comments
The VLAN switch has both tagged and untagged ports. A tagged port can receive and transmit only VLAN
frames. When a port (such as port 1) is associated with multiple VLAN IDs, it must be tagged.
An untagged port can receive both tagged VLAN frames and untagged regular Ethernet frames, but
transmits only untagged Ethernet frames. An untagged port is most commonly used to connect to VLAN-
unaware devices. A tagged or untagged port can be assigned only a single VLAN ID. Up to 16 VLAN filters
can be defined per port. If an SU receives a VLAN packet with an ID that does not match its assigned VLAN
ID or any of the 16 VLAN filters, the packet is discarded.
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