Multicast address

Error Handling

Once an mdns-server instance is created it will attempt to emit all errors as an
‘error’ event type. Unhandled error events may cause an application to crash so
it is recommended to add an error listener to any mdns-server instances.

I.E.

var mdns =require('mdns-server')({  reuseAddrtrue,  loopbacktrue,  noInittrue})mdns.on('error',function(error){console.log('mDNS Server Error',error.message);})mdns.initServer()

When using the auto server initialization by not specifying the noInit: true
option it is possible for an error to occur before your error listener is ready.
In this case a try {} catch {} may be needed when creating the server instance…

var mdns;try{  mdns =require('mdns-server')({    reuseAddrtrue,    loopbacktrue,})}catch(error){console.log('mDNS Server Init Error',error.message);}mdns.on('error',function(error){console.log('mDNS Server Error',error.message);})

Advertising your Arduino using mDNS

Your Arduino program needs to advertise its services so they can be found by mDNS clients. For mDNS, a service is a name, protocol and port number. The client trying to connect to your program will use this information to resolve the Arduino’s IP address and open the connection.

The ESP8266 tool-chain for Arduino includes a compatible mDNS server. To use this server, you’ll need to

1. include , start the mDNS server and register the service,
2. Call to start the server. Here, is the name that will identify your device on the network, so it should be unique. The example below creates a unique name by appending the chip id to the program name using the custom function .
3. Call to advertise the service. The service end-point will be advertised as . For example, if you call in your Arduino program, the end-point will be named . Add the end-point to MegunoLink’s list of services so it will find your device.

Multicast group joins status

Menu: /routing pim join

Group join list of all the group joins that are registered by PIM-SM
Multicast forwarding cache — this section only provides information about current state of multicast cloud at given router, showing states of joins for multicast groups.

IPv6

The prefix holds the value ff for all multicast addresses.

Currently, 3 of the 4 flag bits in the flags field (ff1) are defined; the most-significant flag bit is reserved for future use. The other three flags are known as R, P and T.

Similar to a unicast address, the prefix of an IPv6 multicast address specifies its scope, however, the set of possible scopes for a multicast address is different. The 4-bit sc (or scope) field (bits 12 to 15) is used to indicate where the address is valid and unique.

The service is identified in the group ID field. For example, if ff02::101 refers to all Network Time Protocol (NTP) servers on the local network segment, then ff08::101 refers to all NTP servers in an organization’s networks. The group ID field may be for special multicast address types.

Notable IPv6 multicast addresses

The following table is a list notable IPv6 multicast addresses that are registered with IANA.

Example

Almost minimal setup where multicast routing is necessary:

• multicast sender (server);
• multicast receiver (client);
• two routers running PIM between them.

Multicast traffic in this example will be destined to address 224.0.1.20

Traffic flow:

 Sender -- (subnet I) --> Router A -- (subnet II) --> Router B -- (subnet III) --> Receiver

Router A will be configured as Rendezvous Point.

Enable PIM and IGMP router A:

 > routing pim interface add interface=all
 > routing pim interface print
Flags: X - disabled, I - inactive, D - dynamic, R - designated-router,
v1 - IGMPv1, v2 - IGMPv2, v3 - IGMPv3
 #      INTERFACE    PROTOCOLS
 0   v2 all          pim
                     igmp
 1 DRv2 ether3       pim
                     igmp
 2 DR   register     pim

Configure static Rendezvous Point:

 > routing pim rp add address=<IP of router A>

You may also need to configure alternative-subnets on upstream interface — in case if the multicast sender address is in an IP subnet that is not directly reachable from the local router.

 > routing pim interface set <upstream-interface> alternative-subnets=1.2.3.0/24,2.3.4.0/24

Enable PIM and IGMP router B:

 > routing pim interface add interface=ether1
 > routing pim interface print
Flags: X - disabled, I - inactive, D - dynamic, R - designated-router,
v1 - IGMPv1, v2 - IGMPv2, v3 - IGMPv3
 #      INTERFACE    PROTOCOLS
 0  Rv2 ether1       pim
                     igmp
 1 DR   register     pim

Configure static Rendezvous Point:

 > routing pim rp add address=<IP of router A>

Add route on multicast sender:

# ip route add 224.0.1.20/32 via <IP of router A>

Start sender and receiver programs. You can either write simple programs yourself, or use any of these:

And hey, it works! Client should receive data now.

Usage

var mdns =require('mdns-server')({  reuseAddrtrue,  loopbacktrue,  noInittrue})mdns.on('response',function(response){console.log('got a response packet:')var a =if(response.answers){    a =a.concat(response.answers)}if(response.additionals){    a =a.concat(response.additionals)}console.log(a)})mdns.on('query',function(query){console.log('got a query packet:')var q =if(query.questions){    q =q.concat(query.questions)}console.log(q)})mdns.on('destroyed',function(){console.log('Server destroyed.')process.exit()})mdns.on('ready',function(){mdns.query({    questions{      name'_services._dns-sd._udp.local',      type'PTR'}})})mdns.initServer()setTimeout(function(){mdns.destroy()},10000)

In this example a query will be sent on all available IPv4
and IPv6 interfaces. With loopback enabled these queries
should be recorded by the server. I.E.

got a query packet:got a query packet:

Here there were two query packets because the system has
both an IPv4 and IPv6 address on one interface.

Assuming a device on the local network matches the query
request for ‘foo.local’ the server should record a
response similar to the following…

got a response packet:

Using the mDNS Browser

Open the mDNS Browser by selecting mDNS Configuration from MegunoLink’s gear menu. You can use the Start and Stop buttons to start and stop the mDNS client.

Click the Edit button to show the Manage Services window to setup the services you are interested in (you’ll need to stop the mDNS client first if it is running). Click the New to add a service name, Edit to change an existing name or Delete to remove an entry from the list. Enter the end-point of the service (see below). MegunoLink will search for devices advertising any service in the list.

Select the mDNS services that MegunoLink should search for.

mDNS support is built-into MegunoLink

MegunoLink contains a simple mDNS client (so it doesn’t require any external services such as Bonjour). The mDNS client periodically looks for devices on your network which advertise the services you are interested in. A service, is simply a named port that your Arduino program opens to communicate with the outside world. The Arduino advertises the name of the port using a library, such as the ESP8266mDNS library for the ESP8266 WiFi module.

Each device can advertise many service end-points and many devices may advertise the same type of end-point. Each device should have a unique name, so you can choose the one you want to connect to. In MegunoLink, you’ll select your connection by the type of service and the name of the device.

Bootstrap router candidates

Menu: /routing pim bsr-candidates

bootstrap router candidate configuration

Causes of Multicast MAC address question?

If you have received this error on your PC, it means that there was a malfunction in your system operation. Common reasons include incorrect or failed installation or uninstallation of software that may have left invalid entries in your Windows registry, consequences of a virus or malware attack, improper system shutdown due to a power failure or another factor, someone with little technical knowledge accidentally deleting a necessary system file or registry entry, as well as a number of other causes. The immediate cause of the «Multicast MAC address question» error is a failure to correctly run one of its normal operations by a system or application component.

Television

In digital television, the concept of multicast service sometimes is used to refer to content protection by broadcast encryption, i.e. encrypted content over a simplex broadcast channel only addressed to paying viewers (pay television). In this case, data is broadcast (or distributed) to all receivers but only addressed to a specific group.

The concept of interactive multicast, for example using IP multicast, may be used over TV broadcast networks to improve efficiency, offer more TV programs, or reduce the required spectrum. Interactive multicast implies that TV programs are sent only over transmitters where there are viewers and that only the most popular programs are transmitted. It relies on an additional interaction channel (a back-channel or return channel), where user equipment may send join and leave messages when the user changes TV channel. Interactive multicast has been suggested as an efficient transmission scheme in DVB-H and DVB-T2 terrestrial digital television systems, A similar concept is switched broadcast over cable-TV networks, where only the currently most popular content is delivered in the cable-TV network.Scalable video multicast in an application of interactive multicast, where a subset of the viewers receive additional data for high-resolution video.

TV gateways converts Satellite (DVB-S, DVB-S2), Cable (DVB-C, DVB-C2) and Terrestrial television (DVB-T, DVB-T2) to IP for distribution using unicast and multicast in home, hospitality and enterprise applications

Another similar concept is Cell-TV, and implies TV distribution over 3G cellular networks using the network-assisted multicasting offered by the Multimedia Broadcast Multicast Service (MBMS) service, or over 4G/LTE cellular networks with the eMBMS (enhanced MBMS) service.

Usage

var mdns =require('multicast-dns')()mdns.on('response',function(response){console.log('got a response packet:', response)})mdns.on('query',function(query){console.log('got a query packet:', query)})mdns.query({  questions{    name'brunhilde.local',    type'A'}})

Running the above (change to ) will print an echo of the query packet first

got a query packet{ type'query',  questions{ name'brunhilde.local', type'A', class1},  answers,  authorities,  additionals}

And then a response packet

got a response packet{ type'response',  questions,  answers{ name'brunhilde.local',       type'A',       class'IN',       ttl120,       flushtrue,       data'192.168.1.5'},  authorities,  additionals{ name'brunhilde.local',       type'A',       class'IN',       ttl120,       flushtrue,       data'192.168.1.5'},{ name'brunhilde.local',       type'AAAA',       class'IN',       ttl120,       flushtrue,       data'fe80::5ef9:38ff:fe8c:ceaa'}}

A packet has the following format

{  questions{    name'brunhilde.local',    type'A'},  answers{    name'brunhilde.local',    type'A',    ttlseconds,    data(record type specific data)},  additionals(same format as answers),  authorities(same format as answers)}

Currently data from , , , , and records is passed

Creates a new instance. Options can contain the following

{  multicasttrue  interface'192.168.0.2'  port5353,  ip'224.0.0.251',  ttl255,  loopbacktrue,  reuseAddrtrue}

Emitted when a query packet is received.

mdns.on('query',function(query){if(query.questions&&query.questions.name==='brunhilde.local'){mdns.respond(someResponse)}})

Emitted when a response packet is received.

The response might not be a response to a query you send as this
is the result of someone multicasting a response.

Send a dns query. The callback will be called when the packet was sent.

The following shorthands are equivalent

mdns.query('brunhilde.local','A')mdns.query({name'brunhilde.local', type'A'})mdns.query({  questions{name'brunhilde.local', type'A'}})

Send a dns response. The callback will be called when the packet was sent.

mdns.respond({  answers{    name'my-service',    type'SRV',    data{      port9999,      weigth,      priority10,      target'my-service.example.com'}},{    name'brunhilde.local',    type'A',    ttl300,    data'192.168.1.5'}})

The following shorthands are equivalent

mdns.respond({name'brunhilde.local', type'A', data'192.158.1.5'})mdns.respond({  answers{name'brunhilde.local', type'A', data'192.158.1.5'}})

Destroy the mdns instance. Closes the udp socket.

To start hacking on this module you can use this example to get started

Usage

var mdns =require('multicast-dns')()mdns.on('response',function(response){console.log('got a response packet:', response)})mdns.on('query',function(query){console.log('got a query packet:', query)})mdns.query({  questions{    name'brunhilde.local',    type'A'}})

Running the above (change to ) will print an echo of the query packet first

got a query packet{ type'query',  questions{ name'brunhilde.local', type'A', class1},  answers,  authorities,  additionals}

And then a response packet

got a response packet{ type'response',  questions,  answers{ name'brunhilde.local',       type'A',       class'IN',       ttl120,       flushtrue,       data'192.168.1.5'},  authorities,  additionals{ name'brunhilde.local',       type'A',       class'IN',       ttl120,       flushtrue,       data'192.168.1.5'},{ name'brunhilde.local',       type'AAAA',       class'IN',       ttl120,       flushtrue,       data'fe80::5ef9:38ff:fe8c:ceaa'}}

A packet has the following format

{  questions{    name'brunhilde.local',    type'A'},  answers{    name'brunhilde.local',    type'A',    ttlseconds,    data(record type specific data)},  additionals(same format as answers),  authorities(same format as answers)}

Currently data from , , , , and records is passed

Creates a new instance. Options can contain the following

{  multicasttrue  interface'192.168.0.2'  port5353,  ip'224.0.0.251',  ttl255,  loopbacktrue,  reuseAddrtrue}

Emitted when a query packet is received.

mdns.on('query',function(query){if(query.questions&&query.questions.name==='brunhilde.local'){mdns.respond(someResponse)}})

Emitted when a response packet is received.

The response might not be a response to a query you send as this
is the result of someone multicasting a response.

Send a dns query. The callback will be called when the packet was sent.

The following shorthands are equivalent

mdns.query('brunhilde.local','A')mdns.query({name'brunhilde.local', type'A'})mdns.query({  questions{name'brunhilde.local', type'A'}})

Send a dns response. The callback will be called when the packet was sent.

mdns.respond({  answers{    name'my-service',    type'SRV',    data{      port9999,      weigth,      priority10,      target'my-service.example.com'}},{    name'brunhilde.local',    type'A',    ttl300,    data'192.168.1.5'}})

The following shorthands are equivalent

mdns.respond({name'brunhilde.local', type'A', data'192.158.1.5'})mdns.respond({  answers{name'brunhilde.local', type'A', data'192.158.1.5'}})

Destroy the mdns instance. Closes the udp socket.

To start hacking on this module you can use this example to get started

Ethernet

Ethernet frames with a value of 1 in the least-significant bit of the first octet of the destination MAC address are treated as multicast frames and are flooded to all points on the network. While frames with ones in all bits of the destination address (FF-FF-FF-FF-FF-FF) are sometimes referred to as broadcasts, Ethernet generally does not distinguish between multicast and broadcast frames. Modern Ethernet controllers filter received packets to reduce CPU load, by looking up the hash of a multicast destination address in a table, initialized by software, which controls whether a multicast packet is dropped or fully received.

The IEEE has allocated the address block 01-80-C2-00-00-00 to 01-80-C2-FF-FF-FF for group addresses for use by standard protocols. Of these, the MAC group addresses in the range of 01-80-C2-00-00-00 to 01-80-C2-00-00-0F are not forwarded by 802.1D-conformant MAC bridges.