Questions tagged [multicast]

For questions about multicast communications and protocols.

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22
votes
2answers
11k views

Is multicast on the public internet possible? And if yes: How?

Is it possible to use multicast on the public internet? If yes: How? Are special IP addresses required and where do you get them from?
15
votes
1answer
63k views

What are the benefits and cons of IGMP snooping?

Our new router is asking if we want IGMP snooping enabled. Not being familiar with this, I looked to the internet and got the following wiki description: IGMP snooping is the process of listening ...
12
votes
0answers
612 views

PIM-SM with BSR over SSG5 VPN tunnel

I've created a lab to troubleshoot an issue I'm having with PIM-SM and BSR. There are two sites connected via two Juniper SSG5s (6.3.0r17) with just enough configuration to focus on the problem at ...
11
votes
3answers
4k views

OSPF over vPC on Nexus7k

I'm trying to help a friend with some Nexus issues. The topology is like this: Cat 3750 stack -> vPC -> 2x N7k -> LACP -> Fortigate firewall cluster The 3750 stack is running OSPF to both the ...
10
votes
4answers
5k views

PIM-SM multicast and HSRP/VRRP

I need to set up a PC to listen in on a multicast (PIM-SM) data feed. The multicast sources and (anycast) Rendezvous point are behind a "HSRP/VRRP address" on the other side of a WAN link. (The ...
10
votes
3answers
6k views

Setting up PIM Sparse mode

I am working on trying to setup our network for multicast traffic. In the coming months we will be installing new equipment that sends out multicast traffic. In the past we have only had 1 VLAN so we ...
10
votes
2answers
4k views

KEMP load balancers using UCARP (VRRP) - multicast MAC address not being picked up

Alright - been battling this for at least 20 hours consecutive.. Sorry if this seems like a long rant, or a blog post, but I'm getting to the point of exhaustion. So, here's the deal. We're using ...
9
votes
2answers
5k views

why TTL value 1 in IGMP

why TTL value 1 in IGMP protocol and what are the different values possible in TTL section for Multicasting. What I got from the google is that if TTL value is 1 then it won't leave the LAN, but if ...
9
votes
1answer
5k views

switchport block multicast vs storm-control multicast

I'm not sure what is the difference in behaviour between switchport block multicast and storm-control multicast and I don't think cisco elaborates the difference very well in their documentation, ...
9
votes
1answer
474 views

How to control unwanted UDP traffic (Broadcast & Multicast) on Cisco Router 2911?

Please suggest, we are getting UDP traffic either broadcast or multicast in router 2911 which cause 95%+ utilisation of the router. And we got error in link and business impact due to this. Company ...
8
votes
2answers
24k views

Can I truly multicast over WIFI?

Am streaming UDP over wifi (5ghz) - approx 1.5k/packet... trying to stream to ~10 devices simultaneously, with extremely low latency.. As I understand Wifi, it can never true multicast, as each ...
8
votes
2answers
3k views

Which address should I choose to send a multicast message on an wireles ad-hoc meshed network?

I am trying to implement a wireless multicast ad-hoc network, but I don't know how it works. I think I have to send my packets to a specific 224.0.0.* address, but I don't which one choose. My ...
8
votes
2answers
6k views

IGMP snooping and link-local multicast addresses

I have a network which has many devices sending data to 224.0.0.225 on a VLAN which spans multiple switches. Each device (aprox 12 of them) is sending reporting data at roughly 500-600 kbps. Each port ...
8
votes
1answer
6k views

What is the correct mask to use with 224.0.0.0?

What is the best mask to use to allow computers to use the multicast IP address 224.0.0.0? I've only seen IP addresses using the lower 8 bits, in my case I just see 22 and 251. So my firewall uses ...
8
votes
1answer
986 views

Which address should I use to receive a UDP wireless multicast with iperf?

On computer 1 (192.168.1.3): I made a route to be sure that my communication pass through my wireless card sudo route add -net 239.0.0.0 netmask 255.255.255.0 dev wlan2 I launch iperf with the ...
7
votes
3answers
2k views

OSPF and its use of Multicast

When it comes to OSPF and its use of multicast, am I correct in believing that IGMP forwarding and an IGMP querier is still required within the local segment? My understanding would be without this, ...
7
votes
1answer
1k views

MLD messages during IPv6 duplicate address detection

I was wondering if anyone can shed some light on when Multicast Listener Discovery (MLD) messages ought to be send during IPv6 Duplicate Address Detection. RFC4862 section 5.4.2 gives a detailed ...
7
votes
1answer
8k views

Mitigating a IPv6 malformed packet multicast flood

So we just had our first IPv6 multicast flood in the network this morning. We managed to stop the offending computer by blocking the mac address with: mac-address-table static x.x.x vlan x drop ...
7
votes
1answer
2k views

Why is the NDP Neighbor Solicitation message sent to the solicited-node address?

As I understand it, when Host Alice knows Host Bob's IPv6 address but not its MAC, Alice sends an NDP Neighbor Solicitation (NS) message to the solicited-node multicast address for Bob. Alice knows ...
7
votes
2answers
132 views

VLAN clarification

I've inherited a network with approximately 200 computers and no VLANs configured. We are currently adding a system that uses multicasting to communicate with each other and will be adding VoIP in 2 ...
6
votes
2answers
2k views

How do I mcast multiple pcap files simultaneously with guaranteed ordering and controllable speed?

We capture many pcap files every day on many different multicast groups. For the purposes of testing & benchmarking, we wish to replay these files in an isolated environment and in a controlled ...
6
votes
2answers
2k views

IPv6 Multicast - Purposes for the Interface-Local scope?

On an IPv6 multicast packet, the last nibble of the first hextet represents the Scope of the packet. This defines effectively how far you want your multicast packet to travel. The address makeup is ...
6
votes
3answers
6k views

Wake on LAN across VLANs in IPv6 network

In IPv4, if I want to send a magic packet to a workstation in another VLAN, I enable directed broadcasts in the remote VLAN and send it to the VLAN's broadcast address. This works great. In IPv6, I ...
6
votes
2answers
2k views

How is Multicast IP mapped to Multicast Mac address?

My main concern is why is the address 01-00-5E- and how? Especially 5 and E??
6
votes
2answers
1k views

IGMP Multicast router overrun

THE SYSTEM: I have a L2 Managed 1Gbps switch with IGMP snooping (the switch I'm testing with is a TP-Link TL-SG3216). I have several identical devices (these are embedded devices that we are ...
5
votes
3answers
662 views

Multicast Distribution with PIM

I have to receive some multicast groups for an IPTV platform. I can't use PIM (they don't give me an RP address for the groups...). The provider suggested me to do a join to each multicast group and ...
5
votes
1answer
414 views

What is the difference between Unicast RPF and Reverse Path Forwarding?

What is the difference between Unicast RPF and Reverse Path Forwarding? They both verify the source address of each packet before forwarding it to the destination. Is Reverse Path Forwarding used ...
5
votes
1answer
6k views

Why we can not ping to multicast address 224.0.0.9 of RIP

We know that RIP v2 uses multicast address 224.0.0.9 for periodic broadcast of routing table. So it means that every router configured with RIP V2 is monitoring for any packet with destination address ...
5
votes
1answer
973 views

IGMP snooping in iptv

Host1 wants to join Multicast group as IGMPv3 include (G,S). The same group and source Host2 send as Exclude(G,S) report. what process done in switch?
5
votes
1answer
90 views

IP pim sparse or dense mode

I have an IF/RF station that is receiving RF signals from satellites, then converted to IP to be encoded, decoded, multiplexed, and modulated again to RF so that it's sent to wireless and wired ...
5
votes
1answer
368 views

Juniper EX4600: multicast not working in vlan default. [closed]

I have a Juniper EX4600 switch which I'm using for host connectivity (obviously). Now I need to set up a VRRP/CARP between two hosts that are in the same vlan, and it's the default one. Surprisingly, ...
4
votes
2answers
2k views

Why we use 224 as multicast address in many protocols?

I see in many protocols we use 224 multicast address as like eigrp uses 224.0.0.10 ospf uses 224.0.0.5 224.0.0.6
4
votes
3answers
10k views

Is multicast possible in tcp?

I got an assignment to implement unicast, multicast and broadcast in UDP or TCP in java, so I searched for it and I only got UDP implementation of multicast. My question is following: Is there ...
4
votes
4answers
353 views

Layering unicast addressing over multicasts

My question has to do with layering of unicast over multicast and has two parts. Part 1. IP unicast over MAC multicast First part of the question is whether there is a standard that prohibits use of ...
4
votes
2answers
2k views

Why is MBGP needed?

I've been working on some multicast protocols and I came across MBGP and I want to know why is it needed. The way everyone uses MBGP is that they set up PIM in every routers, and for the inter domain ...
4
votes
3answers
626 views

Multicast routing on Huawei Quidway 5300 Switches

I have been testing a scenario which involves multicast routing for multicast traffic the scenario is pretty simple. I have two L3 switches with OSPF running in between them, two computers are ...
4
votes
3answers
546 views

IPv6 Multicast vs Unicast

I'm currently learning IPv6 and they mentioned broadcast is gone in IPv6 and replaced with multicast and unicast. Are there some situations where multicast or unicast is better over the other in ...
4
votes
2answers
1k views

Alternatives to GRE for multicast over MPLS?

I have an application that requires multicast across our MPLS WAN, and had been using GRE tunnels to facilitate this until recently when I replaced some aging edge routers with HP L3 switches. To my ...
4
votes
1answer
54 views

Function of the P-bit flag in an IPv6 multicast

Currently I'm trying to learn (common) things about IPv6 and started with the address format and the address scopes. Finally I reached the multicast part where my problem with the definiton of the ...
4
votes
1answer
4k views

Is it possible to have same multicast group members listening on different port numbers?

Let's say I have a multicast group 239.0.0.1. If A and B are members of this group and listening on port 6000, I can send data to (239.0.0.1, 6000) and both A and B will receive. Now, if A is ...
4
votes
1answer
14k views

RIP V2 multicasting looks as broadcasting at IP add 224.0.0.9

In RIPv1 the packets are broadcasted out all ports with dest. IP 255.255.255.255. In v2 they are multicasted with dest. IP 224.0.0.9. In Packet Tracer, this v2 packet is transmitted over all ...
4
votes
1answer
1k views

Multicast timer expires

I've a multicast network for security cameras (multiple RPs, bsr, connectivity with OSPF). The problem is that the monitors sometimes stop receiving the video stream. (10.0.0.1, 234.0.0.1), 00:10:11/...
4
votes
3answers
10k views

Inter-switch IGMP on a VLAN with two switches, and a multicast source per switch

I have a network consisting of two HP 2810 switched. Attached to each switch is, on one port, a multicast video coder, and on a different port, a decoder. There are two VLANs - a control VLAN (...
4
votes
1answer
318 views

802.11 multicast buffering due to random back-off mechanism

I am trying to achieve periodic multicast with WAP (Wireless Access Point) [basically trying to stream real time audio data to multiple devices]. The regularity in the interval between successive UDP ...
4
votes
1answer
5k views

What is the difference between source based tree and shared core based tree?

In case of multicast routing, I encountered source based tree and shared cost based tree.What is the difference between source based tree and shared core based tree? In which case they are used? what ...
4
votes
2answers
531 views

IGMP snooping (Bridge operation)

What is Meant by RFC 4541 when it says... 4) All non-IPv4 multicast packets should continue to be flooded out to all remaining ports in the forwarding state as per normal IEEE bridging operations.
4
votes
1answer
804 views

Multiple VLANs under one subnet (for traffic control)

Looking at a fiber ring network of 11 switches on the same subnet, with 3 types of devices per module (device 1, 2 & 3). control room switch 192.168.11.100 module 1 ethernet switch 192....
4
votes
1answer
914 views

Cisco C891F-K9 ISR latency?

What is the multicast routing latency of Cisco C891F-K9 ISR? Please cite references for your answer. I think it's store-forward type and isn't one of the fastest models (given its price!). I've ...
3
votes
3answers
12k views

What are real life examples of broadcast and multicast?

In broadcast routing, packets are sent to all nodes even if they do not want it. What is a real life example of "broadcast"? Almost everything I can think of, like GMail and YouTube, appears to be ...
3
votes
1answer
1k views

What is the advantage of multicasting in IPv6 (compared to broadcast)?

I've been trying to familiarize myself with IPv6 and one thing that's left me hanging is the benefit of multicasting over broadcasting in IPv6. To use Neighbor Discovery Address Resolution as an ...