3Com Nbx 100 And Ss3 Nbx Administration Guide

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Alternate
GatekeepersA zone can contain only one gatekeeper at a time, although multiple 
distinct devices can provide the gatekeeper function in a zone. Multiple 
devices that provide the RAS signaling function for the gatekeeper are 
called alternate gatekeepers. Each alternate gatekeeper appears to each 
endpoint as a distinct Gatekeeper.
To ensure system availability, redundancy, and scalability, the gatekeeper 
can provide RAS signaling function by using multiple physical or logical 
devices, referred to as alternate gatekeepers.
Checking 
ConnectionsYou can use connection checks to pre-qualify an installation and to help 
localize connection problems. H.323 gateway installers can conduct 
connection checks for:
■Gateway Checks
■Network Checks
Gateway ChecksGateway checks can verify that the NBX systems at each end of an H.323 
connection are working properly.
Gateway Self-Check
A gateway self-check is simply an H.323 call that returns to the local 
IP address (loopback test). 
To perform a gateway loopback test:
1Access a ConneXtions H.323 port from an NBX Business or Basic 
Telephone by dialing an H.323 port line number or by using a dial plan 
configured with a ConneXtions pool number.
You must have Super User Group CoS allowed to dial in to a line port 
number directly.
2Enter the IP address of the gateway.
3Verify the connection. If you are using default settings, you are connected 
to the Auto Attendant. If you are not using default settings, you may be 
connected to a different extension number. 
						

							442APPENDIX A: CONNEXTIONS H.323 GATEWAY
Local Considerations
All voice packets that move between an NBX Business or Basic Telephone, 
Call Processor, ConneXtions gateway, and router on the LAN have a high 
priority and high quality of service. 
However, at the router and beyond, network administrators can influence 
H.323 call quality through the priority that they give to H.323 packets at 
both the internet router and at the firewall.If H.323 connections 
consistently experience significant delays, you should review the local 
router and firewall configurations at each side of the H.323 connection.
Network ChecksA network check uses:
■Network Ping
■NetMeeting Connections
Network Ping
A network ping is a packet transfer that checks the logical continuity 
between a personal computer and a specified IP (router) address. For 
example, you can ping your own address, or the default gateway. The 
next ping checks the connection to the IP router at the remote end of the 
intended H.323 connection.
The easiest way to initiate a ping is with a DOS ping command. This 
command sends four pings to the specified IP address. The router at that 
address immediately returns the ping, and the command notes the round 
trip delay for each ping packet. Some firewalls do not return pings for 
security reasons. If the ping test fails, you can use a “trace router” 
command (“tracert”) to find out where the logical connection failed.
To check a connection:
1Access the DOS command prompt from the DOS shell in Windows.
2Enter 
ping on the command line:
ping  (example IP address)
3Interpret ping results:
a
Request timed out (all four times)
■Ping reached the network but couldn’t connect to the host
■(No such address; or the device is down).
■Initial request timed-out 
						

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■(It is normal for a first ping to fail and subsequent pings to 
succeed).
■Subsequent requests timed-out
■(Indicates some packet loss. Rerun using the “-n 100” option. The 
“request timed out” number represents the percentage of lost 
packets. These packets could have been lost in either direction.)
bDestination host not reachable
■Ping couldn’t negotiate a path to the specified address
(PC is not plugged into LAN, incorrect gateway address in route, 
or a firewall blocked the ping).
cApproximate round-trip times in milliseconds
■Ping time greater than 10 ms but preferably less than 300 ms. 
(Ping times can differ because the network often routes individual 
packets along different internal routes depending on congestion.)
4Use 
tracert on the command line:
tracert  (example IP address)
5Interpret trace results:
The 
tracert command lists every IP gateway it encounters as it tries to 
reach the specified destination. It also includes the number of times (3) 
required to reach each intermediate gateway. If a network connection 
failure occurred in route, this command indicates where it occurred.
Because the 
tracert command reveals the chain of logical connections 
across a network, it can be useful for comparing the performance of 
alternative internet service providers. 
NetMeeting Connections
You can also check H.323 voice packets that are sent between systems 
that are running Microsoft NetMeeting. ConneXtions software requires it 
to run G.711 (CCITT mu-law) or G.723.1 compression. NetMeeting is 
available on the Resource Pack CD, or it is available as a free download 
from 
www.microsoft.com.
You can conduct the NetMeeting connect test from the operating system 
that runs the ConneXtions software, or from another PC on the LAN.
You must run NetMeeting and ConneXtions on different PCs. 
						

							444APPENDIX A: CONNEXTIONS H.323 GATEWAY
In addition to the NetMeeting software, participating computers need an 
audio card with a headset (or speakers) and a microphone. The audio 
card must support full-duplex 64 Kbps transfers.
Note that it is possible for a NetMeeting connection to be unsuccessful 
and still have a successful ConneXtions installation. This can occur 
because ConneXtions restricts the range of TCP and UDP ports used but 
NetMeeting allocates its ports from a wider pool. For more information, 
see “Firewall Security”
 earlier in this appendix. If ConneXtions is installed 
with a limited range of allowable ports, and the firewall is configured to 
pass only those ports, it is possible that NetMeeting cannot pass a call 
through the firewall while the more restricted ConneXtions calls can pass 
through.
The following procedure uses NetMeeting to test the connection 
between the operating system that runs the NBX ConneXtions H.323 
Gateway and a remote IP address. This end-to-end NetMeeting check can 
help to recognize firewall problems without the complexity of the NBX 
system and ConneXtions H.323 server.
To make a NetMeeting check:
1From the Start menu, select Settings, and then Control Panel. 
2If you are using Windows NT, double-click Services. If you are using 
Windows 2000, select Applications, and then Services. 
3Select 3ComConnextions from the list, and click Stop.
4Access 
www.microsoft.com using a web browser.
aClick Downloads in the navigation bar.
bIn the Product Name field, select NetMeeting.
cIn the Operating System field, select Windows 95, Windows 98, 
Windows 2000 or Windows NT.
dClick Find It! The latest versions of NetMeeting are displayed. Click the 
version you require.
5Download NetMeeting files and respond to the prompts.
aClick the program name (
NM30.exe) next to Download Now.
bClick OK.
cIn the Save As dialog box, select a folder for the downloaded files.
dClick Save. 
						

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6Install the NetMeeting files and respond to the prompts:
aSelect Open when the download is complete.
bClick Ye s to confirm installation.
cClick Ye s to acknowledge the legal agreement.
dClick OK to accept the default installation directory.
eClick OK to acknowledge successful installation.
7Open NetMeeting:
aClick Next on next two screens.
bEnter your details as required.
cClick Next on next two screens.
dClick Put a Shortcut to NetMeeting on My Desktop.
eClick Next on next two screens.
fClick Te s t .
gAdjust the speaker volume.
hClick Next.
iClick Te s t .
jAdjust the microphone Record Volume.
kClick Next.
lClick Finish.
8To attempt a NetMeeting call:
aClick the NetMeeting icon, followed by the telephone icon.
bEnter the IP address of similar system at remote end, after To.
cSelect Network or Direct Call, after using.
dClick Call.
eConfirm the connection using a speaker or headset and microphone.
9To end the call, click the “hang-up” icon.
Interpreting the Results
The NetMeeting check has three possible outcomes:
■No communication with remote NetMeeting.
Wrong IP address.
Firewall is blocking call setup (TCP) packets. 
						

							446APPENDIX A: CONNEXTIONS H.323 GATEWAY
■Call rings remote end and it answers, but there is no audio.
Faulty connection to a microphone, speaker or both.
Firewall is blocking audio (UDP) packets.
■Calls work in one direction, but not in the reverse direction. Place a 
call to determine which firewall is blocking TCP traffic. Once you 
determine this, it is the remote firewall that is blocking the traffic.
Placing CallsYou can place an outgoing H.323 call from an NBX system in one of 
several ways, as discussed in this section.
See Chapter 2
 for information on how to use the dial plan to set up the 
NBX system to use H.323 ports.
IP Address EntryDepending on how you set up the dial plan, the most convenient way to 
place a call to a new number is to dial a ConneXtions extension list 
(configured within the dial plan), which provides a connection to an 
available H.323 port. If a port is available (not busy), enter the extension 
and IP address from the telephone key pad. Use the 
* key to separate 
the four “octets” in the IP address, and then press the # key to “dial 
now.”
You must configure the dial plan to use ConneXtions. You must have 
Super User Group CoS privileges to perform this test. 
These examples show key pad sequences that request an extension list 
connection and a specific port connection:
8192
*168*1*15# 
where extension list access is used
OR
754 192
*168*1*15# 
if there is no extension list access, or if you want to test specific ports.
The first example begins with an 8 to request any available H.323 port. 
The second example begins with the 3-digit extension (754) of a specific 
H.323 port. The remaining digits in both examples represent the IP 
address of the remote H.323 gateway (192.168.1.15). Note that IP 
addresses are always four octets long. In this case, 15 is the last octet. 
						

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Extension Lists
You can configure H.323 ports for single-digit access (usually 8) instead of 
a specific 3-digit line extension. The single-digit access allows the NBX 
system to select an available line port when you place an external call.
Internet IP line ports and CO (central office) line ports must never be 
assigned to the same extension list because they use very different dial 
plans. Conventional practice is to use 9 for external switched network 
(PSTN) connections and 8 for external IP network connections.
Calls to other NBX systems (or PBX systems) can include a destination 
extension. This example represents a call to an extension (273) on a 
remote NBX system that has an H.323 ConneXtions gateway:
8192
*168*1*15*273#
The # sign tells ConneXtions to “dial now.” The last asterisk, 
*, 
terminates the IP address, but ConneXtions cannot dial the number until 
it sees the “# sign,” or until 4 seconds pass after the last digit. In the 
preceding example, the IP address (192.168.1.15) and the extension are 
presented to the device as the “called party.”
The # sign also precedes the extension as shown below. This allows the 
ConneXtions gateway to complete the IP connection before it presents 
the remaining digits to the remote terminal:
8192
*168*1*15#273
Both configurations produce the same result when dialing into another 
NBX system; however, other PBXs can be position-sensitive. If you are not 
sure, use the first format with the # sign after the extension.
Speed DialsYour telephone system has a speed dial capability that offers a quick way 
to dial frequently called numbers. Each telephone is capable of accessing 
199 previously stored dial sequences with up to 30 characters in each 
sequence. These sequences can represent switched network numbers or 
Internet addresses. Special 3-digit speed dial numbers specify each dial 
sequence.
Speed dial numbers must be preceded by the “Feature” button when 
entered from a telephone. This button distinguishes NBX speed dial 
numbers from ordinary extensions that use the same three digits. 
						

							448APPENDIX A: CONNEXTIONS H.323 GATEWAY
Speed dial numbers can be system-wide or personal. System speed dial 
numbers (700-799) apply system-wide and are programmed by the 
system administrator. Personal speed dial numbers (601 through 699) 
apply only to an individual telephone; they are programmed by its owner.
You can assign any of the first ten speed dial numbers in each type group, 
system or personal, to any Access button on a telephone.
For more information, see Chapter 6 of the NBX Telephone Guide.
Setting Up Speed Dials
The following procedure assumes that you are logged on to the NBX 
NetSet utility as an administrator, and that you know the H.323 port 
extensions that were established during installation.
To set up speed dials:
1In the NBX NetSet - Main Menu window, click Device Configuration.
2Click the Line Card Ports tab. 
3Note the extension number of each listed NBX H.323 port.
4Return to the NBX NetSet - Main Menu window, and click System 
Configuration.
5Click the Speed Dials tab.
6To complete the fields:
aNote a speed dial number. (One-button dialing requires system speed 
dial numbers 700 through 709.
bIn the New Number field, type an H.323 extension, or an 8 (for 
extension list), followed by an IP address, or a system name. Examples 
are:
8192
*168*1*15*273#  (IP address plus extension)
8192.168.1.15
*273#  (IP address plus extension)
[email protected]#  (extension plus host name)
8h323.nbx.com#  (host name, defaults to AA)
Use those characters shown here, that is, no spaces, dashes or & signs.
cIn the Comment field, enter a description with up to 30 characters, 
such as Tie-line to NYC, and then click Apply.
7Verify the speed dial entry by pressing the Feature button followed by the 
new speed dial number. 
						

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One Button AccessYou can configure an Access button on a NBX system to dial a complete 
H.323 (or switched) dial sequence. 
This procedure assumes that all buttons available for one-button access 
are configured in the first ten system (or personal) speed dial locations.
To set up one-button dials:
1In the NBX NetSet - Main Menu window, click Device Configuration.
2Click the Telephones tab or the Group Telephones tab. Select a telephone 
extension or a telephone group.
3Click Button Mappings.
4Associate one of the first ten speed dial numbers with a telephone Access 
button:
aLocate the Ty p e field associated with an available button.
bSelect the speed dial selection (SSD 0 through 9) that is associated 
with a previously programmed speed dial code (700 through 709).
cClick Apply and then click OK (to return).
5Verify the one-button dial feature operation by pressing the new button 
and confirming that it dials the specified number.
Entering Digits
During CallsWhen ConneXtions dials a call, it stores the dialed digits until it connects 
the call. Then it sends those digits, and any subsequent digits, to the 
remote H.323 device if the device supports version 2, or later, of the 
H.323 standard.
The behavior of ConneXtions depends on when the # sign is entered 
during this process.
ConneXtions sends digits as messages, which are more reliable than 
audio tones. ConneXtions also expects to receive digits from H.323 
devices in the same way, and therefore does not have a tone detector. 
This means older (H.323 version 1) devices cannot send or receive digits 
to or from ConneXtions. For example, the current version of Microsoft 
NetMeeting, which sends DTMF tones in the audio stream (in-band 
signaling), cannot use DTMF signaling to pass the Auto Attendant.
In instances where other devices might listen for in-band DTMF signaling, 
the quality of the tone recognition depends on the selected voice 
compression. Tones transmitted by G.711 can be reproduced, but tones 
transmitted by G.723.1 are degraded. 
						

							450APPENDIX A: CONNEXTIONS H.323 GATEWAY
Receiving CallsConneXtions gateways route incoming calls to any available H.323 port. 
The NBX system then connects this port to the extension specified during 
port configuration. H.323 ports are configured through the NBX software 
just like line card ports. Selectable extensions are: 
■Auto Attendant (500)
■Receptionist’s telephone (usually the lowest numbered extension on 
the system, with a default of 1000 on the SuperStack 3 NBX system or 
100 on the NBX 100 system)
■Other extensions (each ConneXtions H.323 port can go to a single 
extension)
Auto AttendantH.323 calls are usually routed to the Auto Attendant. From there, 
NBX callers can reach internal extensions without operator assistance by 
supplying a 3-digit extension when setting up the call (as the called 
party), or by dialing an extension after the Auto Attendant answers. 
Callers cannot get an outside line through the Auto Attendant because 
dialing 9 normally diverts incoming calls to the name directory.
You can configure H.323 calls to appear to go directly to an internal 
extension by adding a 3-digit extension immediately after the last octet in 
an H.323 IP address. Do not use commas, spaces, or hyphens between 
the IP address and an extension when programming an H.323 speed dial 
number. IP network connections do not incur delays like those that occur 
with analog PSTN connections.
8192
*168*1*15*273#
The # sign in this example indicates when the last digit was entered so 
that the Call Processor does not have to wait 4 seconds to determine that 
a caller has no other digits to dial.
Caller ID Response
The Auto Attendant receives caller ID information from an outside 
caller and passes it to a caller-selected extension. On a telephone, the 
caller ID name and extension (if applicable) appear in brackets to indicate 
that the network has not authenticated the enclosed information.