Virtual Transport

The Virtual Transport uses the TUN/TAP interface to create a virtual interface (vif) as the emulation boundary entry/exit point.

Features

The Virtual Transport emulation boundary provides the following set of features: Virtual Interface Management, Raw Transport Interoperability, Bitrate Enforcement, Broadcast Only Mode, and IPv4 and IPv6 Capable.

Virtual Interface Management

The Virtual Transport creates a virtual interface for use as the emulation boundary. IP packets routed to the virtual device are encapsulated and transmitted to their respective NEM for downstream processing. Packets received over-the-air are processed up the NEM stack and transmitted to the NEM’s respective virtual transport for injection back into the kernel IP stack.

The newly created virtual interface is assigned an Ethernet address derived from the NEM Id associated with the transport using the following format: 02:02:00:00:XX:XX , where XX:XX is the 16 bit NEM Id. This allows easy mapping of Ethernet MAC addresses to NEM Ids for unicast frames. Multicast and broadcast frames map to the NEM broadcast address 0xFFFF.

A Virtual Transport managed virtual interface can be configured via configuration parameters or managed externally, for example via DHCP.

Raw Transport Interoperability

The Virtual Transport supports interoperability with Raw Transport emulation boundaries using ARP caching to learn IP network to NEM Id associations.

Bitrate Enforcement

The Virtual Transport supports bitrate enforcement for use with models that do not limit bitrate based on emulation implementation. Set the configuration parameter bitrate to the desired rate in bps to enable bitrate enforcement or 0 to disable.

Broadcast Only Mode

The Virtual Transport supports forced NEM broadcasting of all IP packet types: unicast, broadcast and multicast. Set the configuration parameter broadcastmodeenable to true to enable broadcast only mode.

IPv4 and IPv6 Capable

The Virtual Transport supports IPv4 and IPv6 virtual interface address assignments and packet processing.

Configuration

address: IPv4 or IPv6 virutal device address.

Default: no                    Required: no                    Modifiable: no                  
Type:    inetaddr              Occurrs:  [1,1]

arpcacheenable: Enable ARP request/reply monitoring to map Ethernet address to NEM.

Default: yes                   Required: no                    Modifiable: no                  
Type:    bool                  Occurrs:  [1,1]                 Range:      [false,true]        
Values:  true

arpmodeenable: Enable ARP on the virtual device.

Default: yes                   Required: no                    Modifiable: no                  
Type:    bool                  Occurrs:  [1,1]                 Range:      [false,true]        
Values:  true

bitrate: Transport bitrate in bps. This is the total allowable throughput for the transport combined in both directions (upstream and downstream). A value of 0 disables the bitrate feature.

Default: yes                   Required: no                    Modifiable: no                  
Type:    uint64                Occurrs:  [1,1]                 Range:      [0,max_uint64]      
Values:  0

broadcastmodeenable: Broadcast all packets to all NEMs.

Default: yes                   Required: no                    Modifiable: no                  
Type:    bool                  Occurrs:  [1,1]                 Range:      [false,true]        
Values:  false

device: Virtual device name.

Default: yes                   Required: no                    Modifiable: no                  
Type:    string                Occurrs:  [1,1]               
Values:  emane0

devicepath: Path to the tuntap device.

Default: yes                   Required: no                    Modifiable: no                  
Type:    string                Occurrs:  [1,1]               
Values:  /dev/net/tun

ethernet.type.arp.priority: Defines the emulator priority value (DSCP used for IP) to use when an ARP Ethernet frame is encountered during downstream processing.

Default: yes                   Required: no                    Modifiable: no                  
Type:    uint8                 Occurrs:  [1,1]                 Range:      [0,255]             
Values:  0

ethernet.type.unknown.priority: Defines the emulator priority value (DSCP used for IP) to use when the specified unknown Ethernet type is encountered during downstream processing. Uses the following format:

<ethernet type>:<priority>
```
Default: no                    Required: no                    Modifiable: no                  
Type:    string                Occurrs:  [0,65535]           
Regex:   ^(0[xX]){0,1}\d+:\d+$
```

flowcontrolenable: Enables downstream traffic flow control with a corresponding flow control capable NEM layer.

Default: yes                   Required: no                    Modifiable: no                  
Type:    bool                  Occurrs:  [1,1]                 Range:      [false,true]        
Values:  false

mask: IPv4 or IPv6 virutal device addres network mask.

Default: no                    Required: no                    Modifiable: no                  
Type:    inetaddr              Occurrs:  [1,1]

Statistics

avgDownstreamProcessingDelay: Average downstream processing delay

Type: float                 Clearable: yes

avgProcessAPIQueueDepth: Average API queue depth for a processUpstreamPacket, processUpstreamControl, processDownstreamPacket, processDownstreamControl, processEvent and processTimedEvent.
```
Type: double                Clearable: yes                 
```
avgProcessAPIQueueWait: Average API queue wait for a processUpstreamPacket, processUpstreamControl, processDownstreamPacket, processDownstreamControl, processEvent and processTimedEvent in microseconds.
```
Type: double                Clearable: yes                 
```
avgTimedEventLatency: Average latency between the scheduled timer expiration and the actual firing over the requested duration.
```
Type: double                Clearable: yes                 
```
avgTimedEventLatencyRatio: Average ratio of the delta between the scheduled timer expiration and the actual firing over the requested duration. An average ratio approaching 1 indicates that timer latencies are large in comparison to the requested durations.
```
Type: double                Clearable: yes                 
```

avgUpstreamProcessingDelay: Average upstream processing delay

Type: float                 Clearable: yes

numAPIQueued: The number of queued API events.

Type: uint64                Clearable: yes

numDownstreamBytesBroadcastGenerated: Number of layer generated downstream broadcast bytes
```
Type: uint64                Clearable: yes                 
```

numDownstreamBytesBroadcastRx: Number of downstream broadcast bytes received

Type: uint64                Clearable: yes

numDownstreamBytesBroadcastTx: Number of downstream broadcast bytes transmitted
```
Type: uint64                Clearable: yes                 
```
numDownstreamBytesUnicastGenerated: Number of layer generated downstream unicast bytes
```
Type: uint64                Clearable: yes                 
```

numDownstreamBytesUnicastRx: Number of downstream unicast bytes received

Type: uint64                Clearable: yes

numDownstreamBytesUnicastTx: Number of downstream unicast bytes transmitted

Type: uint64                Clearable: yes

numDownstreamPacketsBroadcastDrop: Number of downstream broadcast packets dropped
```
Type: uint64                Clearable: yes                 
```
numDownstreamPacketsBroadcastGenerated: Number of layer generated downstream broadcast packets
```
Type: uint64                Clearable: yes                 
```
numDownstreamPacketsBroadcastRx: Number of downstream broadcast packets received
```
Type: uint64                Clearable: yes                 
```
numDownstreamPacketsBroadcastTx: Number of downstream broadcast packets transmitted
```
Type: uint64                Clearable: yes                 
```

numDownstreamPacketsUnicastDrop: Number of downstream unicast packets dropped

Type: uint64                Clearable: yes

numDownstreamPacketsUnicastGenerated: Number of layer generated downstream unicast packets
```
Type: uint64                Clearable: yes                 
```

numDownstreamPacketsUnicastRx: Number of downstream unicast packets received

Type: uint64                Clearable: yes

numDownstreamPacketsUnicastTx: Number of downstream unicast packets transmitted
```
Type: uint64                Clearable: yes                 
```

numUpstreamBytesBroadcastRx: Number of upstream broadcast bytes received

Type: uint64                Clearable: yes

numUpstreamBytesBroadcastTx: Number of updtream broadcast bytes transmitted

Type: uint64                Clearable: yes

numUpstreamBytesUnicastRx: Number upstream unicast bytes received

Type: uint64                Clearable: yes

numUpstreamBytesUnicastTx: Number of upstream unicast bytes transmitted

Type: uint64                Clearable: yes

numUpstreamPacketsBroadcastDrop: Number of upstream broadcast packets dropped

Type: uint64                Clearable: yes

numUpstreamPacketsBroadcastRx: Number of upstream broadcast packets received

Type: uint64                Clearable: yes

numUpstreamPacketsBroadcastTx: Number of upstream broadcast packets transmitted
```
Type: uint64                Clearable: yes                 
```

numUpstreamPacketsUnicastDrop: Number of upstream unicast packets dropped

Type: uint64                Clearable: yes

numUpstreamPacketsUnicastRx: Number upstream unicast packets received

Type: uint64                Clearable: yes

numUpstreamPacketsUnicastTx: Number of upstream unicast packets transmitted

Type: uint64                Clearable: yes

processedConfiguration: The number of processed configuration.

Type: uint64                Clearable: yes

processedDownstreamControl: The number of processed downstream control.

Type: uint64                Clearable: yes

processedDownstreamPackets: The number of processed downstream packets.

Type: uint64                Clearable: yes

processedEvents: The number of processed events.

Type: uint64                Clearable: yes

processedTimedEvents: The number of processed timed events.

Type: uint64                Clearable: yes

processedUpstreamControl: The number of processed upstream control.

Type: uint64                Clearable: yes

processedUpstreamPackets: The number of processed upstream packets.

Type: uint64                Clearable: yes

Statistic Tables

BroadcastPacketAcceptTable: Broadcast packets accepted
```
Clearable:  yes
```
BroadcastPacketDropTable: Broadcast packets dropped by reason code
```
Clearable:  yes
```
EventReceptionTable: Received event counts
```
Clearable:  yes
```
UnicastPacketAcceptTable: Unicast packets accepted
```
Clearable:  yes
```
UnicastPacketDropTable: Unicast packets dropped by reason code
```
Clearable:  yes
```