The idea behind Microservices has been with the software industry and developers for about six to seven years now, and it´s definitely a current buzz term which is being heard more and more in the industry.
As I have done in previous years around this time, I would like to take this opportunity to summarize some of the most important issues we have encountered in 2017. This year is proving to be a very interesting year for the telecommunications sector.
At the end of 2015, I remember saying that it had been a very special year for Teldat, as we celebrated our company’s 30th Anniversary. How from a simple technological startup we had become one of the European market leaders in advanced corporate communication platforms. However, 2016 has been as if our 31st year in business, has meant the opening of a totally new era, and indeed it has been so, with Teldat’s launch of SD-WAN!
One of the biggest headaches for a company’s network managers is verifying that contracted service levels are being met for their infrastructure. Carrier services usually include a series of contractual points which are summarized in service level agreements (SLAs). To determine whether a service meets expected quality standards, the customer and carrier will use the metrics stated in the SLAs as parameters for measurement.
The American author John Gray who wrote “Men are from Mars, Women are from Venus” is strongly committed to this theory as he advises that communication is very important in helping to bring a relationship back into balance. However, not only relationship counselors believe in communication. “The Father of Advertising” David Ogilvy, for instance, who Time called “the most sought-after wizard in today’s advertising industry”, believed in the deep impact of communication and I guess we can acknowledge that his worldwide success proved him right.
What does communication mean?
The pivotal question which compulsorily occurs is of course, why does communication have such an important role, to the extent that it can turn an unhappy relationship into a happy one. It even made Dove for instance, become the top selling soap in the U.S. The slogan at that time was “Only Dove is one-quarter moisturizing cream.”
When we have a closer look at the etymology of the word “communication” which comes from the Latin word “communicare” and means “to share” we get a slight hint. The Latin word “communis” means “things held in common”. So by sharing information between each other, we also enter someone’s community (Latin “communion”) and we get in touch with each other. Thus, communication is more than just exchanging information. It is also forming a community with the person you are talking to.
How do we communicate?
So how do we do it? The first basic model of communication by Claude Elwood Shannon and Warren Weaver consisted of 3 basic parts, very similar to radio and telephone technologies: sender, channel, and receiver. The model is comparable to a telephone conversation. The sender was a person speaking into the telephone, the channel was the telephone device and line itself and the receiver was the other person on the telephone listening to the first person. Interferences during the conversation can occur which they defined as noise. The strengths of this very famous model are no doubt the simplicity and generality, but the model explains only the basic parts of communication.
Why is communication so important?
Having learned that communication is more than exchanging information, we come to the conclusion that there must be more to why it is so important to communicate with our families, partners, and friends, and of course with our customers in order to maintain a good working relationship on both sides. This is why modern companies communicate with their customers and partners through various “channels” (speaking in terms of the Shannon-Weaver model of communication): from press releases to articles, newsletters to advertisements, case studies to brochures and flyers, websites to social media sites. However, that is by no means everything. Communication is constantly evolving. An example of a modern communication methodology is a webcast. This allows companies to keep their clients and partners totally up to date. Moreover, it also gives the audience a chance to be interactive. To ask questions about new features, products, etc. As webcasts can be recorded, somebody who missed a webcast can watch it at a later stage via the internet. Webcasts are also convenient because they are easy to join without having to travel. Nevertheless, it is important to communicate face-to-face. So it is therefore essential to get personally in touch through meetings and various events such as road shows, business breakfasts, trade fairs and in-house exhibitions.
At Teldat we are very highly conscious that “communication” is vital in order to “share our information” with our clients and partners. We use all the above methods of communication and are always investigating for new modern communication platforms.
Multimedia streaming is increasingly present in our lives. Streaming allows a user to view or listen, to this content without previously downloading it. A user connects to the server which in turn sends the multimedia content. What however, makes this possible?
The ‘Multicast’ Concept’
There are a series of mechanisms that can send multimedia content from a server to a client but clearly the most important and efficient is the multicast mechanism.
- Unicast: each client requiring multimedia content needs an individual data flow.
- Broadcast: multimedia content is sent to all the network clients independently of whether they want it or not.
- Multicast: this only requires a minimum bandwidth as only those clients wanting the multimedia content receive the data flow.
The main advantage of multicast mechanisms versus other possibilities is real time transmission for multiple clients. By using multicast mechanism in these cases, you save an enormous amount of network resources and additionally improve the multicast content transmission.
‘Multicast Group’ Concept
A group of clients request a specific data flow. The group has no physical or geographical limits and only those clients interested in the multimedia content specifically join the said group through IGMP messages. To identify this client group, a multicast address is used.
A multicast address is associated to a group of clients specifying an interest in receiving a multimedia content dataflow. Addresses run from 126.96.36.199 to 188.8.131.52 and are known as a Class D range.
The server sends a single datagram to the multicast address. The router consequently makes copies and sends them to the clients requesting this data from the said server.
Main IPv4 Multicast Routing Protocols
Local network multimedia content distribution is controlled by IGMP (Internet Group Management Protocol), and is used within the routing domain PIM (Protocol Independent Multicast).
IGMP: IGMP is a protocol used by both the clients and multicast routers to identify the multicast group members.
- Clients specify they belong to a group by sending an IGMP message to their nearest router.
- The routers listen to these IGMP messages and periodically ‘discover’ the active or inactive multicast groups in the subnet.
PIM: PIM is a family of multicast routing protocols that operate based on traditional algorithm routing information, independently of the one being used. PIM creates a series of distribution trees from the servers to the receivers, using the topology information it receives.
There are four `PIM variants: PIM Sparse Mode, PIM Dense Mode, Bidirectional PIM and PIM Source-Specific Multicast. This article concentrates on the most commonly deployed variant: PIM SparseMode.
PIM Sparse Mode (PIM-SM)
PIM Sparse Mode is a protocol for efficiently routing IP packets to multicast groups that may span wide area (WAN) and interdomain networks. The protocol is named ‘sparse-mode’ because it is suitable for groups where a very low percentage of the nodes subscribe to the multicast session.
PIM sends multicast traffic from a source server to all clients who wish to receive this traffic, creating a distribution tree and routing the traffic over essential interfaces only. For each node making up part of the tree there is a single interface towards the root and one or various interfaces towards the clients.
PIM-SM has two types of distribution trees:
- Shared tree: traffic source is a Rendezvous-Point (RP) node, which concentrates all traffic destined to the same multicast group regardless of which server sourced the traffic.
- Shortest Path Tree (SPT): the tree has a single multicast server as source and destination is a specific multicast group. The traffic doesn’t go through any node where traffic is concentrated and always creates the shortest path between the server and clients.
PIM-SM was originally developed to avoid problems occurring with other multicast routing protocols, which failed when applied to wide area (WAN) or sparse areas with few clients, it also ensures the information flows just once over the server to client path and is only sent to clients wanting this information.
As already said, PIM-SM does avoid the problems other multicast routing protocols have; however it can give rise to congestion problems in the network due to traffic concentration in the shared trees, which may lead to packet loss.
Both the PIM Sparse Mode and IGMP are included in Teldat routers, as a result our devices provide the best answer to multimedia content routing today.