Guidelines for implementing dns-sd in an NMOS environment

source ：IP Oktoberfest Speaker ：Gerard Phillips Content arrangement ： Yin Wenpei The speaker gave a brief introduction to DNS-SD How to simplify NMOS End configuration , Then there is an overview of how to deploy such a system .

Catalog

• Migrate to IP The advantages of
• How to make complex systems easy to implement
• unicast DNS-SD
• Ideal transmission
• stay OOB(out of band) Services in the network
• Services in multimedia networks
• Hybrid service model
• Think about how to implement a flexible system

Migrate to IP The advantages of

First of all, we all know , from SDI(serial digital interface) To IP The migration of can bring many benefits , Such as ：

1. flexibility , Large scale project , agility , Connectivity ;
2. technological innovation ;
3. From customization to COTS/ Software / IT.

But according to the analysis , This will lead to a very complex , A system that is practically impossible to implement . Because it involves many aspects , such as ： host IP Address , multicast IP Address ,UDP Port number , Switch port number ,VLAN wait .

however IP Can let us stand on the shoulders of giants ！

How to make complex systems easy to implement

This section uses an example to illustrate how to make a complex system simple and easy to implement .

We can go through IP Address and multicast group to get any information you want to know , But most people only know how to get information through the host name and web address , Or some friendly , A name that makes sense at a glance .

In order to get Amateur TV(ATV) Take the program content as an example , First of all, we don't know about the TV program IP Address , We use the browser DNS The server parses its IP Address , This step will connect your terminal to Google's DNS The server , That is, when the web page tells you that the page is looking for content . It's not because you know IP Address , Just because you know friendly name ( By default, friendly names are assigned to supplement unique identifiers consisting of numeric or alphanumeric codes ). stay WAN The same is true of the end , Each host has a friendly name .

For example , Host name Amwa.tv == 23.236.62.147, Their corresponding RDSa.gplab.local == 192.168.100.20.DNS-SD Can be

—nmos-register.—tcp.gplab.local It can be interpreted as RDSa.gplab.local.

These figures are too difficult to deal with , So we hope we don't have to deal with or worry about these complex numbers , So it came out IS-04 technology . We want to have a registry discovery server , It can be on all our terminals 、 Provide connectivity between more sites and endpoints , And provide services .

Early versions of IS-04 take mDNS Identify as a technology . It's very simple , There is no server , Only the second layer domain , And it's not scalable . So this is not the solution we want .

unicast DNS-SD

unicast DNS-SD Is based on The server - client Technology . The host will use unicast , So you can build a network , Make it routable , Extensible LAN, WAN Port and other characteristics .

Now? , The host only needs to know DNS The location of the server . obtain DNS The location of the server is DHCP The job of , You don't need to know how it works , You just need to know what's on your computer DHCP obtain DNS The location of the server then provides you with a IP Address .

Ideal transmission

Let's imagine an ideal world , It has ：

1. An ideal starting point ;
2. Clearly defined multimedia and control networks , The control network contains DHCP, DNS, Broadcast Controller, IS-04,IS-09;
3. Services are well separated into control ;
4. Multimedia nodes and two ( chart 1 Medium yellow and blue ) Multimedia networks are connected ;
5. RDS The node is connected to the control network .

chart 1 Abstract network environment concept map

Let's dig deeper into this picture , Because each deployment is different , So there will be different effects . therefore , for instance ,RDS(IS-04) The server may be powered by Meida Nodes are directly connected , This deployment method can directly access the host , It provides flexibility for information transmission . Maybe Media The node does not provide... At the interface DNS-SD service , Need to get at a higher level DNS-SD service . in addition , Other special clients have very strict isolation rules , They don't want these things connected to any internal network .

So in order to achieve this ideal transmission , We have many choices , We need to understand the diversity of the entire network environment .

stay OOB(out of band) Services in the network

stay OOB The services in the network are really simple and concise , Pictured 2 Shown .

among , The terminal node of multimedia does not need to be connected with OOB Direct network connection , Therefore, the independence of the multimedia server is guaranteed , And for all hosts, there is only a single DNS and RDS Address , This means that the terminal only needs to know one DNS The location of the server is sufficient , This greatly reduces complexity .

But if the terminal node is in their OOB Port does not support unicast DNS-SD What should I do ？ Now the answer is , If not, you cannot use OOB Network access to multimedia services .

Another drawback is , Unless the device has more than one OOB Interface , Otherwise, poor network conditions will be encountered , The resilience will be low .

chart 2 stay OOB Multimedia services in the network

Services in multimedia networks

Also very simple and concise , No connection is required OOB and Media node .

But the requirements for terminals are more complex , Pictured 3 Shown ：

1. Terminal nodes are connected to yellow and blue multimedia networks respectively , Two different DNS Interface ;
2. Of the terminal node DNS Need to be able to serve both yellow and blue multimedia networks ;
3. The terminal node needs to have an available routing table ;
4. All access terminal nodes need to be able to run unicast at the multimedia interface DNS-SD.

chart 3 Services in multimedia networks

Hybrid service model

Pictured 4 Hybrid service model shown in , It's more complicated , But it's flexible .

You can see ：

1. Media Node and OOB Direct network connection ;
2. Have a single DNS Address ;
3. Can support single Media Terminal nodes ;
4. Can support single OOB Terminal nodes .

The following details need to be carefully considered and designed according to the specific scenarios ：

1. You can use DSN On the server Zonescopes Help you design ;
2. If the terminal node establishes two or more connections at the same time , How to define its behavior ？
3. Care should be taken to protect OOB The network is not affected by unnecessary media traffic .

chart 4 Concept diagram of hybrid service model

Think about how to implement a flexible system

Finally, I leave it for you to think about how to implement an elastic system , In a multi-user , In the case of multiple possible host ports ：

1. Yours RDS How the device provides flexibility ？ You need to use dynamic DNS Do you ？
2. DNS How to be flexible ？ You can support multiple DNS IP The address? ？ Or can you use multiple virtual machines to provide flexibility ？

Attach speech video ：

http://mpvideo.qpic.cn/0bc33qabwaaanyabblybwnrfbxgddpoaagya.f10002.mp4?dis_k=4e71b88d0893017fc9a93270977af2ae&dis_t=1645153302&vid=wxv_2258941864789884933&format_id=10002&support_redirect=0&mmversion=false