Questions tagged [multicast]

For questions about multicast communications and protocols.

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In PIM Sparse Mode, can the Rendezvous Point be the first or last hop router?

In tutorials and configuration examples, usually, the Rendezvous Point is described as the central registry to match multicast senders with receivers. FHRs and LHRs send PIM messages to the RP to be ...
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2answers
47 views

What's so special about the multicast address range?

I'm reading a little on IP multicast and have trouble understanding the significance of multicast address range (224.0.0.0 - 239.255.255.255). What makes this range significant? Why not multicast on ...
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1answer
28 views

How to enable Inter-VLAN multicast traffic on a layer 3 Siemens RX1510 Network Switch using IGMP?

I have a single Layer 3 Siemens RX1510 network switch split into 4 separate VLANs on different subsets. Name | Gateway | Subnet VLAN1 | 198.97.100.123 | 255.255.255.0 VLAN2 |...
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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 ...
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2answers
114 views

How do hosts subscribe to multicast addresses?

So I am having a hard time finding materials online that explains how multicast address are set. I understand what unicast is: Basically one to one communication. In this scenario, an address ...
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1answer
63 views

How can MLDv2 work according to the RFCs 3810 and 4606?

When IPv6 Stateless Address Autoconfiguration is happening, an interface/node has to join the all-nodes multicast address and the solicited-node multicast address AFTER forming a "tentative" link-...
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0answers
11 views

Linux local multicast egress follows FORWARD chain when smcroute is active [closed]

Rather than a configuration issue, this is a "Is this expected behaviour" question. Given the following test box (Stock Ubuntu 18.04 LTS): +---------------------------------------+ | ...
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1answer
54 views

Interaction between multicast sources and first-hop routers (possibily DRs)

I might be missing the obvious but I would like to know how the first-hop routers are aware that multicast sources are sending multicast packets and such packets are eligible for the PIM-register ...
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2answers
88 views

Unicast to Multicast possible?

could I check if it is possible to convert TCP traffic to UDP multicast and if there are any appliances / switches that can do so? E.g. Workstations A, B and C establishes a TCP connection with ...
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1answer
53 views

How to handle multicast address collisions?

Assume 2 multicast IP addresses IP1 and IP2 whose mac addresses are same due to collision Let's say a host's NIC has joined multicast stream IP1 and another host on the original host's subnet joined ...
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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 ...
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4answers
94 views

Why not put unicast address in IPv6 packet containing NDP neighbor solicitation instead of solicited-node multicast address?

This is a follow-up question to Why is the NDP Neighbor Solicitation message sent to the solicited-node address?. Summary: say I would send an IPv6 packet and put the unicast address of the host I ...
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3answers
216 views

Will pinging the multicast “all hosts” IP 224.0.0.1 fill my ARP cache with all hosts on my current subnet?

Just wondering in case I ever have a want / need to see all the hosts on my subnet.
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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 ...
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1answer
151 views

Can communication to broadcast 224.0.0.1 be made to reach hosts outside of the local subnet?

I been asked the question if it is possible for an a IP host to use multicast to address 224.0.0.1 in order to reach (and get a response from) another host which is not on the local network segment ...
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1answer
256 views

Routing Multicast on a single L3 switch

I am currently testing how to route Multicast on a single L3 switch. I am currently testing 2 Vlans. I researched and I know I have to use PIM or Mrouter port for this scenario but that is for when ...
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1answer
99 views

Avoid bottleneck in UDP multicast

The question is that a server is serving a multicast group with UDP. Lets say that its a file server and it will be serving big files (~10GB). Now we have a multicast group with multiple clients. Some ...
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1answer
142 views

Multicast in one VLAN

I need to receive multicast traffic over L2 segment on my client machine. But for some reason I am unable to do it. To my understanding with such scheme I should receive traffic if inbetween Juniper ...
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1answer
59 views

Multicast in enterprise network

Once I have heard from a professional that multicast is forbidden (or not suggested or not allowed) in enterprise networks from 2014. (He referenced to a standard or recommendation document or ...
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1answer
42 views

Purpose of prune message in rpf

I read that when a multicast aware router without receivers received a multicast message, the router will send an upstream prune message. I don't understand what is the purpose of the prune message. I ...
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1answer
337 views

Setting Destination MAC address for RTP/UDP packets

I have a requirement where I have to send the UDP packet to a destination multicast IPv6 address. In addition to that the packets must also have corresponding destination multicast MAC address set. I ...
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0answers
107 views

To multicast or not to multicast over LTE? [closed]

I have an IOT device with static IP connected to a Mikrotik LTE device on ether1. The IOT host sends a multicast packet every second. The packet contains the IP and MAC of the host. IP-Multicast: ...
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1answer
80 views

Defining what type of casting based on IPv4 address

I'm kinda new to networking. I have a small question, how can I determine what type of casting (unicast, multicast or broadcast) is it based on IPv4 address. For example: 142.55.172.200 I tried to ...
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1answer
559 views

Cisco 49XX multicast flooding

I have problem with multicast on cisco 4948. I've got vlan 9 with muilticast, which configured on several ports. Switch floods multicast traffic on all ports configured with vlan 9. It consumes link ...
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1answer
55 views

What practical concerns led to the use of multicast?

Answers to a question on SF explain the differences between broadcast and multicast. It is not clear yet for me which practical concerns brought in the usage of multicast. My understanding is that, ...
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1answer
162 views

Users on one VLAN cannot access multicast resources [closed]

Feel like I'm getting closer to fixing my issue... This is the simplified version of the multicast... -No RPF Failure -pim sparse mode on all interfaces -multicast routing enabled I forced a group ...
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1answer
380 views

Is it possible to use 802.11n to send multicast?

I have tried to set the wifi multicast rates and find that all the multicast packets are send by 80211g, so that the max rate is 54M. Can I use the 80211n to achieve higher rate?
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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 ...
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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, ...
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1answer
37 views

Is it possible that IPv6 multicast address is shown in the “IPv6 Address” column of the “show ipv6 neighbors” command in Junos?

Is it possible that IPv6 multicast address(i.e address from ff00::/8 address block) is shown in the "IPv6 Address" column of the "show ipv6 neighbors" command in Junos?
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2answers
48 views

Can Multicasting be duplicated by broadcasting on a subnet?

Is there any functional difference between: A) Broadcasting to a range of addresses B) Putting the range of addresses into a subnet and broadcasting to that subnet Would it matter if there was a ...
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1answer
107 views

Weird packet lost. Looking for some input

Like me start by saying I'm not an network expert but this situation got me scratching my head and you guys might be able to help. The infrastructure is 4 switches (Dell 2848). 2 For the LAN and 2 ...
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1answer
272 views

Understanding IP multicast in linux [closed]

My ultimate goal is to setup IGMP snooping on a linux machine using netfilter hooks. This is for exploratory purposes to understand IGMP protocol. The topology we are using is as follows: | ...
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1answer
1k views

Using IGMP but Multicast still Flooding

Im new here. I want to ask about the multicast, The first case is, I have switch HP 2530 24 port with 24 10/100 and 2 100/1000 NIC, And i have servers with bandwidth video multicast around 120-...
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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
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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 ...
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2answers
2k views

IGMP and multicast forwarding

So my question is, will using IGMP alone(without IGMP snooping, PIM...etc) making router forwarding multicast traffic? I'm working on a buggy switch, but I don't know about networking too, so I'm ...
2
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2answers
193 views

Cisco: multicast unregistred forwarding on ME3400EG-2CS-A access switch

I am connected to the Internet through an Cisco ME3400EG-2CS-A access switch, routing enabled. Gi0/1 and Gi0/2 are configured as a SVI (VLAN1) and on that ports I attached two pfSense firewalls with ...
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1answer
1k views

Network flooded with ICMPv6 Multicast Listener Report Packets

I recently noticed that 3 out of 4 Unifi APs kept reaching 100% CPU usage. When I jumped onto the networks and took a Wireshark capture I noticed 1000s of these packets being sent in just a matter of ...
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2answers
250 views

redundant vpn to remote location with redundant links

I have this situation: Remote location with 6 devices collecting data and each connected to two VPN routers. Bonding is set up for those computers and data is sent to multicast address. Each VPN ...
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0answers
320 views

STB generate IGMP Leave without reason

In my network STB generates IGMP Leave (in STB logs "End of Stream") without any reason or there is something what I don't understand. There is one exeption STB directly connected to PIM (ASR920) ...
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2answers
5k views

Multicast between VLANs

I've following scenario Upper computer on VLAN 10 is sending some multicast messages and lower computer on VLAN 10 sends IGMP join periodically. Lets say MC address is 224.1.1.1 Now, computer on ...
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3answers
755 views

Translate between multicast addresses

I have an application with a bug that does not recognize a certain multicast address as valid. It's an address used by another system i don't have control over, and these two systems communicate via ...
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2answers
1k views

Command “ip nhrp map multicast dynamic” is not being saved into the configuration

For some reason, my Cisco router is not saving the command "ip nhrp map multicast dynamic". The command is recognized but not being saved to the configuration. I am not receiving any errors. Any ...
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1answer
49 views

Should igmp table lookup misses flood to all ports?

With igmp snooping, upon receiving a multicast packet it looks up the table and decides which ports to forward the packet. What I'm wondering is, if there is not an entry in the table for that ...
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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?
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1answer
133 views

Multicast summarization

I was wondering, does it make any sense to summarize(supernet) multicast IPv4 addresses ? Can anyone please explain why yes, or no ?
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1answer
170 views

Question Regarding IGMPv3 behaviour: Multicast Router appears to send Membership Report?

I'm new to how IGMP works. Recently, I was looking at a packet capture: I see that 172.18.1.3 sends a membership query to the all hosts address, leading me to assume that 172.18.1.3 is a multicast ...
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1answer
498 views

Rationale for EXCLUDE mode in mutlicast IGMPv3 / MLDv2

Both IGMPv3 and MLDv2 have an include and an exclude mode, where a multicast listener can specify to either listen only for packets from some list of source addresses (include) or only for packets ...
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1answer
1k views

IGMP snooping across VLANs

Set up: Core switch: C1 C1 is an L3 switch--there is no router Access switches: A1, A2, A3 VLANs: V1, V2 Hosts: H11, H12, H13, H21, H22, etc. Connections: C1 connects to A1, A2, A3 A1, A2, A3 each ...