Network Tunnel(s)

It allows for the movement of data from one network to another. It involves allowing private network communications to be sent across a public network (such as the Internet). To access NetChannel Tunnels, go to Configuration > Network Tunnels. This displays the Network Tunnel(s) window.

There are following columns in Network Tunnel(s) window:

  • WAN: Wide Area Network or WAN is used to test the performance of a real network. It is either enabled or disabled.
    • If it is enabled, it is denoted with icon.
    • If it is disabled, it is denoted with icon.
  • Tunnel Name: It is the name of the tunnel.
    • It should be unique.
    • Maximum limit is 64 characters.
    • Must start with Alpha (a-z, A-Z) characters
    • Numeric (0-9) characters are also allowed in Tunnel name but after any character input for tunnel.
    • Some special characters (_ -. : ) are allowed in Tunnel name.
  • Source IP: It is the IP address of the source system from where the data is to be transferred.
    • It must be valid and in the proper format, like XXX.XXX.XXX.XXX.
    • It is separated in four parts.
    • Each part must have integer value in between 0 to 255
  • Source Netbits: Bits of IP address, which are used for representing the source network.
    • It should be between 1 and 32.
    • The default value is 32.
  • Destination IP: It is the IP address of the destination system to which the data is to be transferred
    • It must be valid and in the proper format, like XXX.XXX.XXX.XXX.
    • It is separated in four parts.
    • Each part must have integer value in between 0 to 255.
  • Destination Netbits: Bits of IP address, which are used for representing the destination network.
    • It should be between 1 and 32.
    • The default value is 32.
  • Network Characteristics: It is the feature of the network, which is either ‘Symmetric’ or ‘Asymmetric’.
    • Symmetric: In a symmetric computer network, all devices transmit and receive data at equal rates.
    • Asymmetric: Asymmetric systems support more bandwidth in one direction than the other.

From this window, the user can add, delete, or update a network tunnel. The details of these topics are provided in the subsequent sections.

Add Network Tunnel

To add a network tunnel, follow the below mentioned steps:

  1. On the Network Tunnel(s) window, click the Add button.

2. This displays a window where the user can add configurations for a Network Tunnel.

For Example: One tunnel is created named ‘Test’ from Source IP (10.10.50.32) to destination IP (10.10.40.104), where Bandwidth Constraints is fixed with 1000 Megabits per second and it is made under Asymmetric case i.e. all the configuration from source to destination is same for destination to source

3. Here, the user needs to provide various details as follows:

General Details

  • Tunnel Name: It is the name of the tunnel.
    • It should be unique.
    • Maximum limit is 64 characters.
    • Must start with Alpha (a-z, A-Z) characters
    • Numeric (0-9) characters are also allowed in Tunnel name but after any character input for tunnel.
    • Some special characters (_ -. : ) are allowed in Tunnel name.
  • Source IP: It is the IP address of the source system from where the data is to be transferred.
    • It must be valid and in the proper format, like XXX.XXX.XXX.XXX.
    • It is separated in four parts.
    • Each part must have integer value in between 0 to 255
  • Source Netbits: Bits of IP address, which are used for representing the source network.
    • It should be between 1 and 32.
    • The default value is 32.
  • Destination IP: It is the IP address of the destination system to which the data is to be transferred
    • It must be valid and in the proper format, like XXX.XXX.XXX.XXX.
    • It is separated in four parts.
    • Each part must have integer value in between 0 to 255.
  • Destination Netbits: Bits of IP address, which are used for representing the destination network.
    • It should be between 1 and 32.
    • The default value is 32.

Enable WAN Simulation: Wide Area Network or WAN is used to test the performance of a real network. To enable the WAN simulation in the network, select the check box else clear it.

Asymmetric / Symmetric: To apply network characteristics as Asymmetric (that support more bandwidth in one direction than the other does), select the Asymmetric check box. If it is cleared, symmetric network characteristics are implemented where all devices transmit and receive data at equal rates.

  • In case of Symmetric, write option is available for only source to destination. The destination to source has only read option and the same configuration, which has been done for source to destination, is copied for destination to source. In symmetric case, add values for only source to destination in different fields (such as Bandwidth Constraints, Fixed Delay, Packet Loss, etc.) for testing the product.
  • In case of Asymmetric, read and write option is available for both, source to destination and destination to source. The user can individually configure for both the source and destination part. In case of Asymmetric mode, input data for both source to destination and destination to source.

Note: To test the tunnel, enable the WAN Simulation.

Source / Destination Network Configurations

This section is divided into two panes – Left pane and Right pane.

  • Left Pane: It displays the WAN characteristics from Source to Destination.
  • Right Pane: It displays the WAN characteristics from Destination to Source.

Note:

  • If the Tunnel’s Network characteristics (in Tunnel Management Screen) field have Symmetric value, then Right Pane becomes Read-only and automatically gets update when Left Pane is updated.
  • If the Tunnel’s Network characteristics field have Asymmetric value, then Both Panes become Read-Write.

There are following configurations in both the panes:

Bandwidth Constraints

Bandwidth represents the capacity of the connection. Bandwidth is represented as data rate supported by a network connection or interface. NetChannel allows to configure the bandwidth constraints in following units:

Note: To ignore the bandwidth constraints, select the ‘No constraints’ option.

Network Latency

Network latency is a measure of how fast a network is running. The term refers to the time elapsed between the sending of a message from one machine to another (even if the process only takes a few milliseconds, slowdowns can be very apparent over transaction requiring many network packets to be transacted between client and server).

Delay Type

There are following delay types:

Fixed delay (fixed-time)

All network data packets from source to destination takes constant amount of time. For example, if use ‘Fixed Delay’ of 100ms, then all packets will be delayed by 100ms. This can be verified using a simple ping test to host on the local network and it will show the delay of 100ms. If delay is configured in both directions, source to destination and destination to source, ping time will be the sum of both delays.

Random Mean delay

NetChannel allows a user to configure the Delay type as Random. For random mean delay, the user needs to specify delay time and variation time. Actual delay will be a random delay with mean delay +/- variation. In addition, the user can select any one of two type of delay:

  • Purely random delay: All delay times are purely random. Each delay sample is independent.
  • Co-related random delay: Each delay sample is co-related to previous delays. In real world, noise is known to happen in burst that can be best explained by co-related randomness.

Example: Random Delay with mean 100ms ± 10ms variation with 25% co-relation will cause all packets to delayed by a random time between 90-110ms with the current delay to be 25% dependent on the previous delay.

The user can also specify one of following randomness distribution.

  • Uniform Random Distribution
  • Normal Distribution (bell curve): The term bell curve is used to describe a graphical depiction of a normal probability distribution, whose underlying standard deviations from the median create the curved bell shape. A standard deviation is a measurement used to quantify the variability of data dispersion, in a set of given values.
  • Pareto Distribution: Pareto distribution is used to illustrate that many things are not distributed evenly.

Examples of events that may be modeled by Pareto distribution include:

    • The file size distribution of Internet traffic which uses the TCP protocol (few larger files, many smaller files)
    • Hard disk drive error rates
  • Pareto Normal Distribution

Packet Loss

NetChannel allows the user to configure the Packet loss in the network. Packet loss is used to simulate an error condition in which data packets appear to be transmitted correctly at one end of a connection, but never arrive at the other. The smallest possible non-zero value is 0.00001%

  • Fixed packet loss: The number of packet loss is always Fixed percentage of packets is lost in every transaction. NetChannel allows the user to configure the packet loss in percentage.
  • Co-related random packet loss: In this case, the number of packet loss is not fixed. NetChannel also allows the user to configure the packet loss with co-relation value in percentage. Higher the co-relation, more will be the burstiness of packet loss.

Packet Duplication

The duplication of a data packet is handled by introducing unique identifiers. The sender tags each data packet with a unique identifier. The recipient records the identifiers of the data packets and discards packets whose identifiers have already been recorded.

Note that when the duplicate of a data packet occurs due to the loss of an acknowledgement packet, the acknowledgement packet has to be sent even when the data packet is discarded; otherwise the sender would keep resending the data packet.  NetChannel allows the user to configure the Packet Duplication in Network with or without correlation.

Packet Corruption

Packet corruption is a significant source of packet loss. It has distinctive symptoms and root causes.

Root Causes of Packet Corruption:

Root CauseSymptoms
Dirty connectorHigh transmit and low receive optical power
Damaged fiber/cableHigh transmit and low receive optical power (bi-directional)
Bad or loose transceiverGood optical power, affect a single link
Shared component failureCo-located failures
Decaying transmitter laserLow transmit optical power

NetChannel allows the user to configure the Packet Corruption in Network with or without correlation.

Packet Re-Ordering

Packet reordering occurs when the order of packets at the destination is different than the order of the same packets at the source. In other words, in a non-reordered packet stream, the packet sequence number of any arriving packet will be lower than the sequence number of the consecutive arriving packet.

The following example shows a situation with reordered packets; the reordered sequences are underlined.

Using NetChannel, the user can configure of re-ordering of packets in Network in percentage. When using the delay of 10ms and re-ordering of 20%, then every 5th (10th, 15th…) packet is sent immediately and every other packet are delayed by 10ms.