Product Manual
ACCESS NX Rack Manual I. Introduction 12 Applications 12 Audio Coding 12 Transmission Modes and Delay 13 Switchboard Server 13 CrossLock 13 Additional Features 14 AES67 Protocol 14 HTML5 14 II. Diagrams and Installation 15 Rear Panel Diagram and Descriptions 15 Front Panel Diagram and Descriptions 16 Mono vs. Stereo 17 Pinouts - Balanced Audio 17 Pinouts - Contact Closures 17 Pinouts - Serial Port 17 Iii.
Using The Console 18 Making Switchboard Connections 19 Receiving Incoming Connections 19 iV. Using The Device Manager Program 20 Updating Firmware Using Device Manager 22 Network Recovery Mode 23 V.
Advanced Local & Remote Options 33 System Settings Tab 35 Security Settings 36 Connections 36 Contact Closures 36 Switchboard Server 37 CrossLock VPN Settings 37 System Clock 37 Alternate Modes 37 AES67 System 38 Advanced System Settings 38 Security 39 Auxiliary Serial 39 CrossLock VPN Settings 39 BRIC Normal Settings 40 HTTP Settings 40 Modem 40 Standard RTP Settings 41 EBU3326/Sip Settings 41 TCP Settings 42 Miscellaneous 42
Vi. Network Manager 43 Network Manager 43 Ethernet Port Settings 43 Network Locations 44 WLAN Adapter 45 3G/4G Connections 46 Advanced Ethernet Port Settings 47 VIi. AES67 Connections 48 Setting Up For AES67 49 Clocking 49 AES67 Input 50 Setting Input delay 51 AES67 Output 52 AES67 Advanced Options 52 Inputs 52 Outputs 52 ViIi.
IX. Making Connections Via Switchboard 57 X. Making Manual Connections 59 Creating New Remotes 59 Backup Remote 60 Connecting and Disconnecting 61 Special Notes for Manual CrossLock Connections XI. Setting Up Your Switchboard Account 61 62 Logging In and Setting Up Switchboard 62 Creating Users 63 Contact Lists 63 Following Contact Lists 64 Shares 65 Managing Multiple Contact Lists 67 Bulk Actions for Contact Lists 68 Switchboard Theory and Concepts 71 XII.
Pots Codec Setup for NX Rack Compatibility 78 Using NX Rack with POTS 78 Rate Drop vs. Retrain 78 Troubleshooting a POTS Connection 79 XiV. About The Algorithms 81 AAC 81 HE-AAC 81 HE-AACv2 81 Linear PCM* 81 FLAC* 82 G.722 82 Opus 82 Algorithm Codec Profiles Chart 83 XV. Multistreaming Multistreaming Arrangements 84 85 NX Rack Initiates the Call 85 NX Rack Rack Receives the Call 85 Using CrossLock with Multistream Connections 85 XVi.
Setting Up a Multicast Remote 87 Time-To-Live 87 Changing Port Numbers for Multicast 87 XvII. Streaming Server Function 88 Decoding a Stream 89 Simultaneously Connecting NX Racks and Streaming 89 XVIII.
Stunning Success 95 Fix of Last Resort 95 XiX. License & Warranty Disclosures for NX Rack 96 License 96 Warranty 97 XX. Switchboard Traversal Server Disclaimer Traversal Server Disclaimer 99 99 XXi.
Decode Side Settings Only 109 Encode Side Settings Only 109 Full-Time or Triggered Connections 109 APPENDIX D: Information For IT Managers 110 Incoming Services 110 Outgoing Services 110 APPENDIX E: Connections To MultiRack 111 BRIC Normal Connections 111 Manual CrossLock Connections 111 Making Connections With Switchboard 112
ABOUT COMREX Comrex has been building reliable, high-quality broadcast equipment since 1961. Our products are used daily in every part of the world by networks, stations, and program producers. Every product we manufacture has been carefully designed to function flawlessly, under the harshest conditions, over many years of use. Each unit we ship has been individually and thoroughly tested. Comrex stands behind its products.
I. INTRODUCTION Congratulations on purchasing the Comrex ACCESS NX Rackmount codec! The NX Rack leverages the core functionality of the original ACCESS Rack, which was first introduced in 2006 and quickly became the world’s leading IP audio codec. The NX Rack carries the ACCESS line forward, promoting an entirely new hardware and software platform. The NX Rack provides an elegant way to move high-quality linear or compressed audio over sub-optimal networks with very low delay.
End-to-end coding delay in Linear modes is less than 25 ms. Delays when using FLAC and Opus modes are less than 30 ms. AAC modes incorporate around 100 ms total end-to-end delay while HE-AAC modes deliver around 220 ms. In addition to coding delay, network propagation and jitter buffers will add delay to any IP link and are network dependent. Switchboard Server Switchboard is a standard feature with NX Rack that allows the codec to “sync” with Comrex’s cloud-based traversal server.
HTML 5 Previous firmware versions for Comrex codecs provided a web-based control page powered by Adobe Flash. As Flash has lessened in popularity and impedes operation on many mobile browsers, NX Rack (and older Comrex products with new firmware) now delivers web-based control using the modern HTML5 standard.
II. 1 NX RACK DIAGRAMS AND INSTALLATION 12 2 3&4 5&6 7 8 9 10 11 13 14 Figure 1 Rear Panel Diagram and Descriptions 1 AC Input - An IEC connector for the main power. NX Rack works on worldwide AC power at 110-240 VAC 50-60 Hz, auto detecting. 2 Analog/AES3 Input Switch - This switch determines whether the Line In Left/AES3 In XLR connector is used for analog or AES3 digital audio input. 3 Analog Audio Input Left/AES3 - Apply balanced analog audio to be sent over the network here.
18 15 16 17 Figure 2 Front Panel Diagram and Descriptions 15 Send - Peak meter that displays the level of audio sent locally into the NX Rack, regardless of an active connection. Proper level is indicated by peaks driving the Green and Yellow LEDs, while avoiding lighting the Red LEDs (which indicates clipping). 16 Receive - Peak meter that displays the level of audio being received from the far end when a connection is active.
Pinouts - Contact Closures Contact Closures are available via the male 9-pin GPIO port on the back of the NX Rack. Inputs are triggered by shorting the respective input to Pin 5. Outputs consist of an open collector circuit which, when inactive, will offer a high-impedance path to Pin 5 and, when active, will offer a low impedance path to Pin 5. These outputs are capable of sinking up to 200 mA at a voltage up to 12 V. Do not switch AC mains power using these contacts.
iii. QUICK START - MAKING CONNECTIONS WITH NX RACK This section skips over many of the details concerning the configuration of remote connections with NX Rack, and focuses instead on the minimum information needed to establish a connection. NX Rack connections with the use of the Switchboard server will be covered. MORE ABOUT PROFILES Refer to Page 32 for more information about creating profiles on NX Rack. Profiles, once created, can be assigned to any remote connection on the Connections page.
MAKING SWITCHBOARD CONNECTIONS On the Web Interface, select the “Connections” Tab. This Tab will populate with a list of available remote codecs to call. When the NX Rack is “synced” with Switchboard, connections to other codecs in a user’s Switchboard account are simple. Go to the listings on the bottom that appear with a “Gear” icon on the left side. Any units with a Green Gear icon are available for Switchboard connections.
iV. USING THE DEVICE MANAGER PROGRAM Firmware updates for the NX Rack should be handled using Comrex Device Manager, a Windows- and MAC OS-executable program that can be downloaded from the Comrex website. Device Manager can also be used for license installation and IP configuration. Please note: In order to configure an ACCESS NX Rack unit for the first time (without knowing the unit’s IP address), Device Manager must be run on a computer located on the same network (e.g.
Figure 7 Set up Ethernet and Wireless Generally, it is recommended to configure the Ethernet port of an ACCESS NX Rack for a static IP. This will facilitate access to the Web-based Interface with a browser and allow for easier configuration of routers or firewalls (if necessary). If the NX Rack is to be installed on a managed LAN, Comrex recommends consulting with the IT services provider about obtaining a static IP address.
Figure 8 Network COnfiguration UPDATING FIRMWARE USING DEVICE MANAGER While Device Manager is open and synced to a codec, it’s a good time to check to see if an update is available for the product. To do this, select the Firmware tab, shown in Figure 9 below. The unit’s current firmware and the most recent version of firmware for the unit are listed at the top of the tab (1 in Figure 9).
1 2 3 Figure 9 Firmware tab NETWORK RECOVERY MODE Since the Ethernet settings are made with a web connection, keying in incorrect static IP information can result in losing access to the Network Manager interface entirely. If this happens, it is possible to be “locked out” of the unit (i.e., unable to log in). Device Manager has a network recovery tool to help with this: Network Recovery Mode.
Figure 10 network recovery mode 24
V. CONFIGURING THE NX RACK The NX Rack is primarily controlled by using a browser to access the built-in web server, which offers an HTML5 user interface page. Alternatively, a similar page is displayed when a keyboard, video monitor, and mouse (abbreviated KVM) are attached to the rear panel of the NX Rack. This is called the Console Interface. The main differences between the console and the web-based interfaces are: 1) There are no audio level meters displayed on the console interface.
1 2 Figure 12 Connections Tab CONNECTIONS TAB The Connections Tab is the first window in the configuration interface. This allows for monitoring device connectivity and controlling connections. In this tab the names and IP addresses of remote units can be saved. To add a new remote unit to the list, select the “+” icon on the right side of the list. A dialogue box will appear asking for a name for the unit as well as its IP address. An algorithmic profile must be selected for the new codec unit.
1 2 4 3 5 Figure 13 Dashboard Tab 1. The audio level meters give a quick indication of send and receive levels. 2. The Contact Closure section gives a visual indication of the state of each input (local) and output closure (remote). The input closure boxes also function as buttons to trigger closures locally. 3. The Active Connections section gives an indication of any currently active connections. If more than one connection is active, they will display in a list here. 4.
Figure 15 jitter/packet error graph The left graph represents the work of the Jitter Buffer Manager. The area of most interest is the light blue area as shown in Figure 15, which illustrates a spread of jitter values (referenced to the current play out pointer) over the last second. If this area covers a large span, the relative jitter is high. If the light blue section of the graph is small or invisible over a time period, less jitter is present.
The CrossLock Stats are similar to the information available on the Active Connections graph, which shows streaming performance without regard to the CrossLock layer. The CrossLock Stats show finer details about network performance in both directions than can be obtained through the Active Connections graph. CrossLock stats are shown for both the data being transmitted from the local codec and the data being received by the local codec. All relevant stats are available for both directions.
CROSSLOCK SETTINGS Clicking the CrossLock Settings field during an active connection will display the CrossLock sliders. There is a slider available for transmit and receive operation. For most CrossLock connections, the sliders should be left at their default Automatic Delay Mode settings. But during connections on unusual networks, these sliders are designed to quickly adjust the current delay settings. The sliders will reset when a CrossLock connection ends.
provide stability. These “zones” scale, increase and decrease in size based on the history of jitter experienced by CrossLock on the network. In “Auto Delay” mode, the dark dot signifies the “Current Delay”, which is the best compromise value calculated by the system to balance stability and delay. By changing the “Automatic Delay Mode” switch to manual, the “Target Delay” indicator can be dragged left or right to override the automatic settings, and increase or decrease the delay.
BUILDING A PROFILE To build a new profile, select Add New Profile (1 in Figure 22) and a new profile appears on the list labelled New Profile. Select it to populate a set of options, starting with the profile Name (2 in Figure 22). Here the profile can be renamed to something easier to remember. Next is the Channel option (3 in Figure 22), which allows for selecting between a standard Comrex IP connection (BRIC normal) or one of the other connection modes offered by NX Rack.
Encoder - It is unnecessary to define any decoder types when using ACCESS because they automatically adapt to the incoming stream. Using this menu, users can select the encoder used to send audio from this ACCESS (local) as well as the encoder used to send audio to this ACCESS (remote). The default value of the remote encoder is to follow the local encoder (i.e., it will send exactly the same codec mode it receives). This is defined as Follow Mode in the remote encoder selection table.
Retransmit Squelch Max - The longest period of data loss during which the squelch function is active. Default is two seconds. During the squelch period, the buffer manager ignores the relative jitter experienced and does not adjust buffer size to compensate. Fixed Delay - This option simply sets the Delay Cushion and Delay Limit at a similar value, so that the delay buffer is defined to the chosen value and will not increase or decrease significantly.
avoidance provides the system a license to step down to a lower encode data rate if desired. This will happen automatically and with no audio interruption. Step down congestion avoidance is not enabled in the Linear PCM mode. UDP Reliability - UDP, the Internet protocol used by BRIC Normal connections, does not have any inherent error correction capability. UDP reliability adds an intelligent algorithm that requests packet resends when appropriate above the base UDP level.
SECURITY SETTINGS Remote Control Password - This allows for a defined password for the web GUI and firmware updates. The default password is comrex (lowercase). CONNECTIONS Unit Name - Users are encouraged to name their codecs here. The default name of a codec is the unique Switchboard ID (MAC address) of the unit. By changing this to something familiar and unique (e.g. roving reporter, weather guy, etc.), you will see this name change reflected in several places: 1.
SWITCHBOARD SERVER Switchboard Enabled - This option enables the use of Switchboard to connect to remote units. (See Making Connections Via Switchboad on Page 57 for more information on using the Switchboard Traversal Server.) Server Address - Address of Switchboard Server. Secure - Enable secure connections to Switchboard Server. Static CrossLock Peers - When using CrossLock without Switchboard, remote peers can be managed in this list.
• Accept Incoming Connections - This determines if this NX Rack is used for incoming normal IP connections. If this function is not enabled, NX Rack will only support outgoing calls using BRIC Normal Mode. Modem • Accept Incoming Connections - This allows an NX Rack to listen for and automatically answer incoming calls.
AES67 SYSTEM AES67 Enabled - Enables the use of the AES67 AoIP engine. This is disabled by default. Network Interface - Allows selection of which network interface should be used for AES67. Users have the option between Primary and Secondary network interfaces. The secondary interface is selected by default. Network Interface Usage - Choose whether selected interface is used for AES67 only, or also for general IP connections. AES67 Frame Size - Allows selection for the size of AES67 frames.
SECURITY Remote Control - This enables remote control and firmware update functionality. This option may be changed in the System console. This setting is “View Only” in the Web GUI. Remote Diagnostics - When activated, this option allows for remote diagnostics capability. The default setting is Off. Web Server Port - This controls the port that the UI web server uses when remote control is enabled. The default setting is TCP 80.
Always Connect - Allows users to attempt to maintain a VPN connection to a selected peer whenever possible. Default is set to None. BRIC NORMAL SETTINGS IP Port - This option defines the incoming UDP port—the number to be used for incoming IP connections. The default is UDP 9000. Crosslock connection is defaulted to UDP 9001.
Accept Incoming Connections - Listen for and automatically answer incoming calls. Incoming Connection Profile - Use this profile for incoming connections. IP Port - Allows users to designate an incoming network port. RTP Compatibility Mode - Enables compatibility with select RTP audio streaming devices. Return Channel Enable - Enables a return channel sent back to the transmitter for incoming calls. Return Channel Encoder - For incoming calls, this specifies the codec to be used for the return channel.
VI. NETWORK MANAGER NETWORK MANAGER Located in the three-line “hamburger menu” in the upper left hand side of the Web-Based Interface, the Network Manager allows configuration to the network settings for NX Rack. Clicking on that tab will bring up the screen shown in Figure 24. The available networking connections from NX Rack are presented on the left hand side of the screen in the Select Network Device section.
Figure 25 ethernet port default settings For users who wish to have a Static IP address for their units, this can be configured by editing the settings for the “Default” Active Network Location. First, select to expand the Default settings under Network Locations. Select IP Type to open a drop-down selection screen. This will give users the option to change the “Default” Network Location to Static IP, DHCP, or Gateway IP types as shown in Figure 26.
Figure 27 ethernet port default settings Once a Network Location has been added, it can be easily implemented through the Active Network Location selection in the Adjust Device Settings. WLAN ADAPTER While the previous section detailed use of Ethernet Port connectivity with NX Rack, users additionally have the option to use WiFi and 4g cellular modems in making connections.
When setting up a WiFi connection, users will require the use of a USB WiFi adapter to begin making connections. Once this has been installed, the adapter will populate in the Select Network Device section of the Network Manager Tab as the WLAN Adapter (Figure 28). This adapter must be Enabled prior to using or scanning it. The WLAN Adapter can be enabled by selecting it in the list, selecting “Enabled” under the Device Manager Settings, and setting it to “Yes”.
Modem-Reported Indicator allows users to use the modem-reported value for the number of bars of signal strength indicated, which is generally more accurate. Use of this option may cause trouble with certain modems. Modem must be re-attached after changing this option.
VII. AES67 CONNECTIONS AES67 is an Audio-over-IP (AoIP) standard for intra-studio audio routing. It’s not intended to be an out-of-studio distribution technique, but rather to replace the Analog/Digital audio ports with an Ethernet cable. This makes audio wiring simpler (standard Ethernet cable) and moves the routing of audio into the networking domain. While AES67 is the standard, several pre-standard systems have gained popularity.
• NX Rack can only be set entirely for AES67 or Analog/AES3 operation. It’s not possible to mix modes for input/output audio. All XLR ports on NX Rack are entirely disabled when in AES67 mode, including outputs. SETTING UP FOR AES67 AES67 settings are located in the System Settings section in the Main Menu. Open the tab and choose the AES67 System options. This is shown in Figure 30. Figure 30 AES67 System CLOCKING Before enabling AES67 mode, it’s important to have a PTP Clock on the network.
AES67 INPUT Next you’ll need to choose or define the AES67 input stream you intend to use. Chances are you’ll be doing this on the controller software for your AoIP network. It’s important to set up the system output (and thereby NX Rack input) audio channel to be AES67 compliant. If you don’t know how to do that, the system-specific cheat sheets available on the Comrex web site can help.
Figure 32 sdp settings Whether you’ve found your stream using discovery or manual SDP, once it’s selected, NX Rack will search your network for the stream and attempt to lock onto it. The status of this process is shown under the Input 1 header and should eventually show “Receiving RTP”. SETTING INPUT DELAY The default settings for AES67 input streams may work well for some streams, but often it’s important to manually set the amount of delay applied to the input stream in order to make it stable.
AES67 OUTPUT When AES67 is enabled on NX Rack, an AES67 output stream is automatically created. This stream has the following parameters: • 2 channel • 48 kHz sampling • 1 ms packet timing • SAP and Ravenna Advertisement • Multicast destination address 239.1.x.x (Where x.
DSCP - This is a flag applied to outgoing packets that tells your switches about priority. The AES67 default is 34, and should be changed only when special requirements exist. Payload Type - This is a value sent in outgoing stream advertisements. AES67 default is 98. If your AoIP system has special requirements, it can be changed here.
VIII. MAKING CROSSLOCK CONNECTIONS ON NX RACK Comrex first introduced CrossLock—its technology that creates an additional reliability layer to ensure quality broadcast connections—with version 4.0 firmware in 2016. As an increasing majority of users updated their units to CrossLock-capable firmware, connections made using CrossLock became the norm for Comrex codecs and are considered standard in NX Rack and ACCESS Codec connections.
Figure 36 CrossLock VPN One limitation of CrossLock is that each codec that joins the CrossLock VPN must be familiar with the others. This process takes place automatically when Switchboard is used. As detailed in section IX, connections that don’t use Switchboard need special configuration. MULTIPLE NETWORK SETUP In the case of more than one network attached to an NX Rack (e.g. two Ethernet cables, a Wif-fi or 4G adapter, etc.
CrossLock Connections to MultiRack Without CrossLock active, a codec will make BRIC Normal connections to MultiRack instance #1 on port 9000. Instance #2 will connect on 9002 and instance #3 will connect on 9003. These are on the MultiRack side, and the remote codecs will all use their default ports of 9000. The CrossLock connection between the Comrex hardware happens over a single port (9001) but the BRIC Normal connections take place virtually on their usual legacy ports within that VPN.
IX. MAKING CONNECTIONS VIA SWITCHBOARD ON NX RACK This section describes the procedure of making and receiving connections on NX Rack via the Comrex Switchboard server. This is the easiest way, but not the only way, to make NX Rack connections. Before connections are made this way, you must set up and configure a Switchboard Account as described in Section XI. If you don’t want to use the Switchboard server to make connections, skip this section and go to section X, Making Manual CrossLock Connections.
Once your Switchboard peers are configured, connecting to one is simple: 1. Select the desired Switchboard peer. 2. Make sure the “gear” icon is green. 3. Click “Connect” in the upper right corner. Switchboard connections can be ended on either end of the link, by choosing the active connection in the list and clicking “Disconnect”. Incoming connections will appear as new entries in the Switchboard peer list while they are active. They can be disconnected the same way.
X. MAKING MANUAL CROSSLOCK CONNECTIONS Creating new Remotes When connections are added to the list manually, we call them “remote entries”, or “remotes” for short. To create a new remote connection, click on the “Plus Sign” (+) on the right of the screen (1 in Figure 38) to Add A New Remote Connection. This will bring up a dialogue box where a new remote’s parameters may be defined (Figure 38). 1 Figure 38 Edit Remote Settings Choose a name for the remote, (e.g.
Figure 39 Profile manager tab Back up remote NX Rack features an ability to have an automatic backup to a designated remote connection. A specific backup connection (for when the primary fails) is designated when a new remote is created. As shown in Figure 40, selecting the backup option opens a menu that allows selection of other outgoing remotes that have been created.
If the primary remote is restored and NX Rack can detect a valid signal, it will automatically disconnect the backup and revert back to the primary remote. To enable Fall Forward, click the “Fall Forward” option in the Edit Remote Settings prompt and select Yes (Figure 40). CONNECTING AND DISCONNECTING Once the remote connection entry is completed in the Connections Tab, highlight the remote and select Connect.
XI. SETTING UP YOUR SWITCHBOARD ACCOUNT The Switchboard Traversal Server is a service built and maintained by Comrex on the public Internet that provides users a directory of other users, facilitating connections to devices that would normally have trouble accepting incoming IP connections. Use of Switchboard is free and comes activated from the factory. Use the instructions in the user interface chapters of this manual to configure Switchboard on the NX Rack unit.
Note: MultiRack instances must be added to Switchboard individually. Instance 1 Switchboard ID is the same as the unit MAC Address, while Instances 2-5 use the same MAC address, with a suffix added to designate the instance Switchboard ID. As an example, if the primary Ethernet MAC address on a MultiRack is 00:01:40:c0:0d:15, that’s the ID input for MultiRack instance #1. Instance #2 is added as 00:01:40:c0:0d:15-2, instance #3 uses -3, etc.
By default, a master Contact List is created that contains all codecs in an account. Every codec in the fleet uses the master list by default. For users uninterested in segregating codes on their account, the default configuration will work fine. NOTE: Assigning a Contact List to a codec determines what gets displayed in its own list. It does not have any impact on how that codec is displayed on other devices. FOLLOWING contact lists Each unit also has the ability to Follow a Contact List.
Figure 48 follow cOntact list On the next screen, check the Contact List(s) that you want this codec to Follow and press “Update Contact List” (Figure 48). One important point to remember: Following a Contact List on a codec only determines which units get displayed on that codec’s own list. It has no impact on how that codec itself is displayed on other devices.
Figure 50 share a device To create a Share, click the Sharing tab and then select “Add New Share” (Figure 49). The following screen then allows users to choose which codec(s) they want to include in a Share (Figure 50).
Figure 52 Sharing accounts Finally, while it is possible to delete Shares, Comrex recommends disabling them instead. This will stop the Share and won’t require any future work to recreate it. To disable a Share, simply click the orange Disable button on the bottom right of the Share edit page (Figure 53).
Figure 54 multiple contact lists If multiple Contact Lists have been designated as “Followed“ on a unit’s Switchboard interface, each Contact List will appear at the bottom of the Connections tab (Figure 54). To view and/or connect to the unit(s) within a list, select the list and press the Open Folder button on the upper right. Figure 55 viewing list devices While viewing the units in a list, the units will be displayed and the lists themselves will temporarily disappear from the screen.
Figure 56 bulk actions To do this, press the Bulk Action button in the bottom-right corner of the Contact List tab (Figure 56). The three steps to create a Bulk Action are: 1. Choose the type of action to perform. 2. Select the codecs targeted with this change. 3. Identify the Contact List that will be impacted by the change.
Figure 58 Bulk device selection After completing this step, specify whether to target the units that are a part of a Contact List or the units that are Following that list (i.e., the option in the yellow-outlined box on the middle-left of the above figure). Note: Bulk Actions can ONLY be performed on ENTIRE Contact Lists. They CANNOT be performed on individual codecs or on a portion of a Contact List.
Switchboard Theory and Concepts Switchboard is useful because it’s not always simple to connect two devices which are essentially “peers” over the Internet. There are two major reasons for this. First, to initiate a stream to a device over the Internet requires knowing its IP address. This is the number that gets applied to the destination field of the IP packet, so Internet routers can determine how best to send it along its way. Every device that connects directly to the public Internet must have one.
The challenges of connecting codecs behind NAT routers will be addressed in more detail shortly. For now, remember that one of the problems NAT servers add is that private IP addresses delivered to codecs (and the only addresses of which the codecs are aware) have no bearing on the public addresses seen from the Internet.
This can work well for fixed installations, but it’s not always an easy task to obtain that kind of security access on corporate routers. Additionally, forwarding functions are implemented differently depending on the hardware. One can easily imagine the complications of obtaining or managing port forwarding on the LAN when arriving at a new remote venue. This would likely encounter a large amount of resistance or confusion on the part of local IT staff.
A good way to think of this is that an outgoing packet “punches a hole” in the router, through which authorized reply packets may be returned to the codec for a limited time (Figure 62). Figure 62 bidirectional communication Switchboard aids in breaking through these different types of routers for incoming calls. Because it is in constant contact with all subscribed codecs, it can send and receive test patterns to determine whether one or more NAT routers exist on a link and what type they are.
XII. OPERATING NX RACK IN A 24/7 ENVIRONMENT NX Rack can be configured for “always on” operation. This allows for constant STL communication and operations requiring long-term connections. In BRIC Normal mode (the default mode of operation), NX Rack transfers all its audio data via the UDP 9000 protocol. This is in contrast to most web-based connections like browsing and email, which use the bidirectional TCP protocol. UDP, unlike TCP, is not “connection oriented” (i.e.
Figure 63 always connect to setting Backup Remote NX Rack has an additional option for constant connections. When building a remote entry, a field is available for backup options, and one of these options is “Keep Retrying This Remote” mode. In a similar fashion, using this mode will allow the unit to disregard the timeout value and keep a persistent connection attempt. The difference is that the Disconnect function still works and the connection will not be re-initiated on a power-up.
Additionally, there is a box in the Change Remote Settings tab labelled Automatically fall forward. If this box is checked, the system will constantly attempt to reconnect the primary remote while connected to the fallback remote. If connection is successful, the connection to the “Fallback” will be terminated.
XIII. POTS CONNECTIONS NX Rack is capable of connections over modem links. This mode emulates the function of Comrex POTS (Plain Old Telephone Service) codecs, which have been used for years to deliver high-quality audio over standard, dial-up telephone lines. This mode provides for a point-to-point connection between the codecs (i.e., no internet where NX Rack is used), and the call is placed directly from one NX Rack (or legacy codec) to the other.
Figure 65 connections tab during an active pots call Selecting Rate Drop will force the system to drop to the next lowest connect rate at any time. Audio transfer will be interrupted momentarily while the units negotiate the new connect rate. Alternately, Retrain will force the system to initiate the entire training sequence again (the “chat” sounds heard at the beginning of a call). Audio loss will occur for a longer time (approx.
• At minimum, connect a few minutes before airtime to assess the connection quality. Setting a MaxRate on the POTS codec is highly recommended. MaxRate usually should be set at a level or two below the maximum unrestricted rate. This will provide a “guard band” against noise and distortion which may cause errors on the line. • If operation starts to degrade after a long period of connection, it’s possible the phone line parameters have changed.
XIV. ABOUT THE ALGORITHMS When building profiles for NX Rack and remote devices, there are several different audio encoder options to use for each direction of the link. Different audio encoder options each have advantages and disadvantages, depending on the situation. The following is a refresher on audio codec algorithms to assist in making the best choice. AAC This algorithm is a highly regarded standard for compressing audio to critical listening standards.
FLAC* This encoder compresses audio data using a lossless algorithm. This means that the audio extracted from the decoder is identical to the audio input to the encoder, with no coding artefacts. FLAC typically removes 30-40% of the network data compared to Linear PCM, but the actual data rate is variable and is based on the complexity of the coded audio. Using FLAC over Linear PCM typically results in a slightly higher (5 ms) overall delay. G.
Algorithm Comparison Chart for ACCESS NX Rack AAC Required Bitrate Coding Delay Audio Bandwidth 64 kb/s 69 ms 20 kHz D1 Mono 96 kb/s 69 ms 20 kHz D2 Stereo 128 kb/s 69 ms 20 kHz D3 Dual Mono allows independent programming to be sent on both L&R channels 128 kb/s 69 ms 20 kHz D4 Stereo 128Kb 256 kb/s 69 ms 20 kHz D5 Dual Mono 256Kb allows independent programming to be sent on both L&R channels 56 kb/s 69 ms 20 kHz D6 Mono 56Kb 96 kb/s 69 ms 20 kHz D7 Mono 96Kb 160 kb/s 69 ms
XV. MULTISTREAMING NX Rack supports the ability to run one encoder per connection, but this single encoder stream may be sent to up to three destinations simultaneously. This capability is referred to as a Multistream, as the encoder creates a separate but identical outgoing stream to each decoder. (Note: A User’s Internet connection must be able to support these streams.
Multistreaming Arrangements The following includes two examples of Multistream arrangements involving the NX Rack. In the first environment, the NX Rack that is serving the Multistream initiates calls, and in the second, the serving NX Rack accepts all of the incoming connections. NX Rack initiates the call In the “Multistreamer as caller” model, two different profiles will be built on NX Rack A. The first profile, labelled “Multi-Duplex”, will be defined as a standard, duplex NX Rack connection.
XVI. IP MULTICAST IP Multicast is an efficient way of delivering NX Rack digital audio streams to multiple locations. This involves relying on the network to distribute the stream to the locations that require it, rather than creating an independent stream for each user. Performing an IP Multicast requires the use of an IP Multicast-capable network. The commercial Internet, with few exceptions, is not capable of supporting IP Multicast. Some private LANs and WANs are IP Multicast-capable.
The important settings for Multicast are: • • Sender/Receiver - Determines whether this particular NX Rack is designed to generate and encode the IP Multicast stream (send) or decode one (receive). Encoder Type - Determines the algorithm format of stream to be used by the Multicast encoder—not relevant for decoders. In addition to the basic options for IP Multicast profiles, clicking the Advanced box will allow setting of the same Advanced Options available for Normal BRIC (Unicast) profiles.
XvII. STREAMING SERVER FUNCTION NX Rack has the ability to act as a streaming server, delivering AAC and HE-AAC to compatible PC-based media players. Currently tested media players include WinAmp, VLC, and Windows Media Player 12 and up. By default, streaming server functionality is turned off. To enable it, go to the System Settings tab of the User Interface and choose HTTP Settings option. Under the first option, set Accept Incoming Connections to Enabled (Figure 70).
The Genre, Info URL, and Public options may be set for anything, or left alone. These options, if applied, will be embedded into the stream. Decoding a Stream To decode a stream, open one of the supported players and select the option to open a URL-based stream. In Winamp and VLC, input the address of the NX Rack in the following format: http://192.168.0.
XVIII. MAKING EBU3326/SIP-COMPATIBLE CONNECTIONS Comrex codecs (and many other brands) have a set of protocols that allow easy IP connections between units. In general, when connecting between Comrex hardware, it’s best to use these proprietary modes to take the most advantage of the features of the product. However, many users are concerned about getting “locked in” to a certain codec brand.
EBU3326/SIP Modes A function of placing a SIP-style call is the ability to register with a SIP server. This is a server that exists somewhere on the network, usually maintained by a service provider. Several free servers exist that can offer registration, like Onsip.com. The NX Rack allows EBU3326/SIP calls to be placed or received with or without registration on a SIP server.
• The password on the SIP account. Figure 72 shows how this information can be applied: by enabling the Use SIP Proxy option under EBU 3326/SIP on the Systems Settings tab. Figure 72 EBU3326/SIP Settings Once this information is correctly entered, a new field appears in the “Registration Status” box located on the Connections tab (Figure 73). Figure 73 Sip status The status will reflect the progress of the registration process. When complete, this will display Online.
SIP registration can be very simple with some servers, and others can require more advanced settings, which are described in the Advanced Topics section on the following page. Making Registered SIP Calls When registered, calls made using an EBU3326/SIP profile behave differently than normal. The address field, regardless of whether it is a SIP URI or an IP address, is forwarded to the server. No connection attempt is made until the server responds.
• routers that have shorter or longer binding timings, i.e., the router may have a tendency to “forget” that the codec is ready to accept incoming calls and block them. SIP Domain - This only applies to Registered mode. It’s the name of the network controlled by the SIP server. This parameter must be passed by the codec to the server. Under most circumstances, this is the same as the server/proxy address, and if this field is not populated, that is the default.
In point-to-point connections this isn’t possible, and some hacks are required to make this work. The first place to look is the router, as many modern routers are aware of this issue and may be configured to ease connectivity. If a router supports the SIP Application Layer Gateway (ALG), enabling this option can fix the issue. The router will read the SIP handshake, find the outgoing address field, and replace it with the public IP. This is a valuable solution in environments where the router supports ALG.
XIX. LICENSE & WARRANTY DISCLOSURES FOR ACCESS NX RACK Licenses MPEG-4 audio coding technology licensed by Fraunhofer IIS http://www.iis.fraunhofer.de/amm/ ACCESS uses proprietary and open-source software programs. Some of the open-source programs are licensed under the Gnu Public License (GPL). For more information on GPL see http://www.gnu.org. As per the GPL, source code for this software is available on request from Comrex on CD-ROM or other electronic format.
Further copyright notice for ncurses, dropbear PuTTY and libxml2 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copy
The next two paragraphs apply to all software contained in this product: WITH THE EXCEPTION OF THE WARRANTIES SET FORTH ABOVE, THE PRODUCT (MEANS COLLECTIVELY THE HARDWARE AND SOFTWARE COMPONENTS) IS PROVIDED STRICTLY “AS-IS.” COMREX CORPORATION AND ITS SUPPLIERS MAKE NO WARRANTY, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR WARRANTY AGAINST LATENT DEFECTS.
XX. SWITCHBOARD TRAVERSAL SERVER USE DISCLAIMER TRAVERSAL server disclaimer You have purchased a product from Comrex that uses the Switchboard TS (Traversal Server) to provide the ability to locate Comrex hardware via the Internet and to aid in the making of connections when certain types of NAT routers are involved in the link.
XXI.
EC Declaration of Conformity for R&TTE Directive We: Manufacturer’s Name: Comrex Corporation Manufacturer’s Address: 19 Pine Road Devens, MA 01434 hereby declare on our sole responsibility that the product: Comrex ACCESS NX Rack Digital Audio Codec to which this declaration relates is in conformity with the essential requirements and other relevant requirements of the R&TTE Directive (1999/5/EC).
U.S. and Canadian Regulatory Information for the ACCESS NX Rack This equipment complies with Part 68 of the FCC rules and the requirements adopted by the ACTA, as well as the applicable Industry Canada technical specifications. On the bottom of this equipment is a label that contains, among other information, a product identifier in the format US:DXDMD01BACCRK. If requested, this number must be provided to a U.S. telephone company.
APPENDIX A - HOTSWAP NX Rack connections are able to utilize Hotswap, allowing users running CrossLock in “Dual Network” mode to designate a primary and secondary network. This secondary network (e.g. wireless 4G) serves as a backup to the primary in case of network failure. Hotswap is a System Setting in NX Rack. Figure 74 Hotswap A typical usage scenario would be a codec that is active 24/7 providing a STL connection as shown in Figure 74.
Setup Setup for HotSwap is done entirely on the end of the link that has dual networks connected. On the NX Rack, the best way to set up HotSwap is via the Network Manager page, accessible via the web-based interface. Navigate to the three-line Main Menu icon in the upper left hand corner of the screen and select Network Manager. Before entering the Network Manager, the secondary network should be attached to the NX Rack via USB or Ethernet.
Exit the Main Menu and navigate to the System Settings page. Under CrossLock VPN, locate the entry labeled “Redundant Transmission” (Figure 77). Change this from the default “Off” to “On”, and then click “Apply Changes”. Figure 77 CrossLock redundant transmission Finally, set one of the contact closures to sound an alert when the HotSwap function is engaged. Still in the CrossLock VPN settings, select “HotSwap CC unit”.
Figure 79 Hotswap CC indicator 106
APPENDIX B - IP COMPATIBILITY The NX Rack is capable of encoding and decoding a choice of three different types of non-NX Rack streams: Standard RTP, Luci Live and Zephyr Xstream. The choice is exclusive—i.e., you must set the NX Rack specifically for the type of stream you wish to be compatible with, and you will remain incompatible with the other two types unless you change it. This setting has no effect on normal NX Rack functions, which continue to operate as before. 1.
• Outgoing Connections - Build a profile using the Profile Manager on the NX Rack and select a Channel Mode of Standard RTP. Then choose an Xstream-compatible encoder for the outgoing call. The Xstream will control what type of stream, if any, is returned to the NX Rack. 3. Standard RTP - This mode is set to receive a basic, unformatted AAC stream within a standard RTP/UDP structure. At present, this mode does not offer compatibility with other industry devices.
Appendix C - NX Rack on Unidirectional Networks Under most circumstances, NX Rack requires an IP path in both directions for successful connections, even when audio is being sent only one-way. For networks that provide data only in one direction, it is possible to use Standard RTP mode to establish and maintain these links. This section describes how to set that up. The codec has several compatibility modes under the Standard RTP channel mode.
APPENDIX D - Information for IT Managers The purpose of this appendix is to describe all open ports and services available on the Comrex NX Rack. The Comrex NX Rack is a device designed to move real-time, wideband audio over IP networks. The main network interface is 1000BaseT-Ethernet. The device contains an optimized version of Linux kernel. The IP parameters are set by a computer on the local LAN using a proprietary broadcast UDP protocol.
APPENDIX E - CONNECTIONS TO MULTIRACK The purpose of this appendix is to describe how to make connections to Comrex ACCESS MultiRack. BRIC NORMAL CONNECTIONS The Comrex ACCESS MultiRack allows users to make up to 5 separate AES67 connections. This feature allows additional setup including the assignment of separate UDP ports for each MultiRack Instance. UDP 9000 is the default port for BRIC Normal connections. Instance #1 on MultiRack will use the UDP 9000 port by default.
MAking Connections With Switchboard In order to use Switchboard, users must first have an account with the server. This account can be obtained by contacting Comrex at 978-784-1776 / 800-237-1776, or by emailing techies@comrex.com / info@comrex.com. Only one account is required for each group of codecs. Once a username and password are provided, navigate to switchboard.comrex.com in a web browser. When first accessing Switchboard, there will be a notice stating that no units have been added to the account.
