In this blog post, I will explain some of the Multicast basics that most of us look for. MPLS Multicast and many other Multicast Design, Troubleshooting, and Multicast Deployment topics are explained in the different blog posts on the website. Also, this post will cover the many fundamental Multicast frequently asked questions briefly. For a more detailed explanation of the particular topic, you can check our other blog posts on the website.
Before we start, please note that if you are looking for IP and MPLS Multicast video course, you can click here.
What is Multicast used for?
There are many reasons in the real life for Multicast, but mostly we are seeing it in the financial networks, stock exchange, Large Campus Networks for IP Surveillance, and IPTV Multicast purposes.
When it comes to the deployment details, although we will cover them in separate blog posts, in IPTV, Source Specific Multicast, in Financial Networks, Bidirectional Multicast is used.
Also, using Multicasting provides resource optimization, which means, less bandwidth, less source, and receiver CPU and Memory usage it can provide.
IP Multicast Routing
There are many Multicast Protocols for Multicast to work in the Networks but when it comes to Multicast Routing, today, as of 2022, PIM is the only Multicast Routing Protocol. PIM stands for Protocol Independent Multicast and here I covered the details for it. In early 2000, DVMRP was used before PIM.
DVMRP stands for Distance Vector Multicast Routing Protocol and it is similar to PIM Dense Mode. We cover PIM Dense and PIM Sparse Mode, as different PIM deployment models in a different blog post on the website.
IP Multicast Routing Protocol, PIM is used for providing Multicast Streaming from Multicast source to Multicast Receiver, by using Layer 3 IP Unicast Infrastructure.
What is Multicast Traffic?
We can carry video, voice, or data multicast traffic between the source and the receiver. All different data types can be Multicast Traffic. Important to understand that, we are sending the same information to multiple receivers, at the same time and Network devices replicate this information.
What is Multicast IP Address?
Many people confuse this. We have 3 different entities to that we assign an IP address. Multicast Source, which is also referred to as Multicast Sender, Multicast Receiver, and Multicast Group.
IP Multicast Source and IP Multicast Receiver always get Unicast IP Address. We only assign Multicast IP Addresses to the Multicast Groups. Okay, then the question is below.
What is Multicast IP Address Range?
Multicast IP Address range is also known as Class D IP Address Range and it is 224/4.
It starts from 220.127.116.11 and up to 18.104.22.168
Quite a big range and inside this, IANA reserved 232/8 for Source-Specific Multicast, SSM purpose.
Which is Multicast MAC Address?
The multicast MAC address is a special value that begins with 01-00-5E in hexadecimal.
The remaining portion of the Multicast MAC address is created by converting the lower 23 bits of the IP multicast group address into 6 hexadecimal characters
Between Multicast IP Address and multicast MAC Address, there are 5 Bits overlaps. Thus, 32 different Multicast groups can share the same Multicast MAC address. This usually is a consideration when we do the planning for Multicast IP addresses for the Multicast Groups.
Which of the following is a multicast routing protocol?
Let’s make a quick test.
The answer is PIM. HSRP is a first-hop redundancy protocol. BFD is used for failure detection for fast convergence. NHRP is the Next Hop resolution protocol, used in DMVPN.
In this post, only a few of the multicast basic topics are mentioned briefly, for a deeper explanation of many other Multicast topics, please check other posts on the website.