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Questions tagged [multicast]

For questions about multicast communications and protocols.

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Should (IPv6) multicast subscribers send report to query?

I am waking through RFC3810 and playing with MLDv2. From that RFC I thought when anyone send query for group :: (all groups) and send it to address ff02::1 all subscribers on segment should send its ...
FoxVK's user avatar
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1 vote
0 answers
152 views

How to forward UDP unicast messages to multiple destinations [closed]

I am trying to forward a UDP Unicast message so that it cant be received by multiple computers. Can anyone point me in the right direction for how to accomplish this? Here are the details: There are ...
James Duvall's user avatar
0 votes
1 answer
88 views

High latency - dense-sparse mode PIM

Colleagues, good day! In my prod, I notice large delays to some switches behind which there are hosts with multicast reception I wanted to know if my multicast is set up correctly, is it normal that ...
Глеб Щеголев's user avatar
1 vote
1 answer
62 views

Can ELI/AAI/SAI addresses be Multicast?

In a slideshow by IEEE regarding the Structured Local Address Plan (SLAP), I saw the following table: SLAP local identifier SLAP Quadrant Z bit Y bit X bit M bit second hex digit ELI 01 1 0 1 0 A ...
Daniel Marschall's user avatar
1 vote
0 answers
36 views

Should a multicast router punt the multicast packets in addition to routing those packets if the router has an interface in this multicast group?

If the multicast router has the (S,G) route present and the same destination address G is also set on one of the router interfaces, then should the router send the packets addressed to group address G ...
Martin's user avatar
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1 vote
1 answer
73 views

Why does a PIM DM assert loser reply with a prune?

In PIM Dense Mode, why does an Assert loser send a Prune message to the winner? What is the actual motivation for this?
Marcus's user avatar
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31 views

What are the triggers for PIM-DM prune and assert messages?

There are articles explaining the PIM-DM mechanics, and they only confused me. Considering the most common topology, that of three routers, connected to each other like a triangle as such: R1 -- R2 \ ...
Marcus's user avatar
  • 191
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2 answers
59 views

What ways are there to make sure router multicast tables are up to date?

I've been reading on IGMP v3 and think I understand the basics of how to join a multicast group - sending a Membership Report Message. But I'm not sure what the "best" or even conventional (...
Andreas's user avatar
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1 answer
69 views

How does a PIM router know which neighbour is the upstream router?

I understand that certain PIM messages such as Join/Prune and Graft have a field called 'Upstream Neighbour Address' used to indicate the recipient of the message, which is the upstream router for a ...
Marcus's user avatar
  • 191
1 vote
1 answer
37 views

Is there an IGMPv1 querier router after all?

I recently looked into the mechanics of IGMPv1 and v2. Reading RFC 1112, I understand that in IGMPv1, the Querier Router functionality does not exist. All IGMP configured routers in a local network ...
Marcus's user avatar
  • 191
5 votes
2 answers
424 views

What does 'moving packets away from the source' in RPF means?

I recently started studying multicast and I am a bit confused by how reverse path forwarding is explained. Most of the sources describe RPF as 'moving packets away from the source' but I understand ...
Marcus's user avatar
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1 answer
44 views

ipsrc multicast group

I'm looking at some traces where a TTL exceeded in transit ICMP message with ipsrc as mcast is captured. The ICMP message is referencing the original ip header with a correct structure [ipsrc ucast, ...
nseu's user avatar
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1 vote
1 answer
326 views

Multicast destination address and port translation (NAT/PAT)

I have a requirement to translate multicast traffic destination address and port number. I see that Cisco has a feature called Multicast service reflection which translates the IP address, but it does ...
Shivani's user avatar
  • 11
0 votes
1 answer
112 views

IPv6-over-IEEE802.15.4 Multicast scope

An IPv6 Multicast address is defined as | 8 | 4 | 4 | 112 bits | +--------+----+----+-------------------------------------+ |11111111|flgs|scop| group ID ...
Eduardo Rodrigues's user avatar
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1 answer
94 views

When using multicast, all users have same bandwidth?

I'm reading https://ieeexplore.ieee.org/abstract/document/9370130 and in this paper, achievable rate for the uplink transmission from user n to the UAV is w_n is the bandwidth allocated to user n(...
new_be's user avatar
  • 25
3 votes
1 answer
92 views

Two multicasts from same source not reaching a destination

I have a single multicast source (Server A) sending to destinations 239.0.0.226 and 239.0.0.227, the source being directly connected to Switch A on VLAN 100. Switch A is sending dozens of multicasts ...
John Moffitt's user avatar
0 votes
2 answers
958 views

UDP supports multicasting and broadcasting in transport layer or application layer?

We know that UDP does supports multicasting and broadcasting. My question is which layer "UDP supports multicasting and broadcasting"? Is it transport layer or application layer? We know ...
S. M.'s user avatar
  • 398
1 vote
1 answer
184 views

Ospf multicasting with two different group

Suppose I have one ospf network where two multicast group exists. And some routers is ospf which belongs to one group or multiple group (Like: routers E, H) and router is layer3 router (Like: ...
S. M.'s user avatar
  • 398
1 vote
0 answers
92 views

How do I set up IPv6 multicast over an MPLS carrier?

I'm setting up an MPLS carrier with VPNs in GNS3, using Cisco 7200 routers. Exact version I'm using is C7200-ADVIPSERVICESK9-M Version 15.2(4)S5, but I'm willing to upgrade/change if that's needed. On ...
Thomas's user avatar
  • 121
3 votes
1 answer
872 views

IPv6 neighbour discovery blocked by MLD snooping switch

I recently noticed that my IPv6 multicast traffic was being broadcasted to all hosts connected to a switch, even those that had not subscribed to the traffic. To fix this, I enabled MLD snooping on ...
Malvineous's user avatar
2 votes
1 answer
680 views

If a switch doesn't support multicast, are multicast packets simply flooded out all ports?

If a switch doesn't support multicast, are multicast packets simply flooded out all ports? This would allow multicast enabled hosts to at least still receive the multicast frames. Follow up question. ...
jester's user avatar
  • 127
1 vote
1 answer
377 views

broadcast instead of multicast for CARP/VRRP/keepalive

In many cloud environments, multicast is blocked therefore when trying to configure CARP/VRRP customer needs to add a dedicated switch. For example, CARP partially works if using a vSwitch from Hetzer,...
nbari's user avatar
  • 125
2 votes
3 answers
704 views

Why does OSPF use flooding despite using multicast?

We know that flooding is only possible in layer2 switch. But in OSPF router in layer3 uses flooding with multicasting. Suppose we have one router in OSPF uses multicast address 225.0.0.9. If router ...
S. M.'s user avatar
  • 398
0 votes
2 answers
544 views

Class D network for multicasting between group

We know Multicasting is defined as a single source sending to multiple recipients on a network when the receiver broadcasts a signal for acceptance. Multicasting has its own Class D IP addressing ...
S. M.'s user avatar
  • 398
1 vote
1 answer
430 views

IGMP in multiple switches with multiple Senders and Receivers in same VLAN

I am trying to send multicast traffic from 3 Senders to corresponding Receivers in same VLAN (100) spread across 3 switches. I setup a Querier in one of the switch, but it doesn't seem to forward ...
codeCat's user avatar
  • 63
2 votes
0 answers
145 views

No entry in the multicast RIB while PIM join is present

I have a router which receives multicast traffic from the source over a multicast LSP(signaled by LDP): root@PE3> show pim join detail Instance: PIM.master Family: INET R = ...
Martin's user avatar
  • 1,109
0 votes
1 answer
144 views

Juniper vMX router silently drops SSM traffic

I have a Juniper vMX router with two interfaces: ge-0/0/0.0 facing the multicast sender and ge-0/0/2.0 facing the multicast receiver. The router receives multicast packets addressed to 232.1.1.1 on ...
Martin's user avatar
  • 1,109
2 votes
2 answers
636 views

Query regarding IGMP Querier Election Process

I wanted to understand how a querier election takes place. Say we have to L3 devices with ip address 10.1.1.2 and 10.1.1.1. PIM is not enabled anywhere. I checked around and found that the flow would ...
Neil Roy's user avatar
1 vote
1 answer
101 views

How Pruning avoids loops in Protocol Independent Mulitcast (PIM- SM)?

I can not think of a scenario, how pruning avoid loops in PIM-SM when a router joins a SPT. I understood that it avoids duplicate messages, but how it avoids loops? I want a scenario where the router ...
Sourabh Choure's user avatar
1 vote
1 answer
2k views

Forward Avahi mDNS packets from one network to another [closed]

I have a Linux device connected to two different networks. eth0 is connected to 198.18.248.x and wlan0 is connected to 198.19.255.x. Another device connected to the 198.18.248.x network and it's ...
Mihai's user avatar
  • 111
0 votes
3 answers
301 views

PIM Packet and NAT

Is it possible to NAT PIM Join packet? Assume the receiver and the source are in two different networks (address regimes). Thus NAT is required. The upstream source and the groupe are included in the ...
huseyin39's user avatar
  • 107
0 votes
1 answer
168 views

What are the benefits of using MP-BGP multicast address family, under the context of inter PIM domains multicasting?

Under the context of inter PIM domains multicasting, 1 RP on each PIM domain (2 domains), attached with eBGP, with MSDP peering to exchange the actives sources, what are the benefits of using the MB-...
bdes31's user avatar
  • 1,085
0 votes
0 answers
111 views

static IP multicast routing with IPSEC

for a specific application, I need to route a multicast flow with IPSEC (we use a CISCO ASA 5508 firewall), I am not a network expert then I will try to explain as best as I can our issue I don't need ...
Gcomel's user avatar
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0 votes
0 answers
90 views

Does multicast over tunnels (e.g., GRE) require IGMP/MLD?

When subscribing to a multicast group on a tunnel device such as a GRE tunnel, are you supposed to participate in IGMP/MLD over that tunnel in order to announce your membership in the multicast group? ...
joshlf's user avatar
  • 327
0 votes
1 answer
1k views

How to Stream from VLC using Multicast? [closed]

I have the following topology: With the following router configurations: R1: hostname R1 ! boot-start-marker boot-end-marker ! ! ! no aaa new-model no ip icmp rate-limit unreachable ! ! ! ! ! ! no ip ...
Rodrigo Pina's user avatar
1 vote
0 answers
422 views

Multicast traffic through Cisco3850

I have a test scenario and trying to pass multicast traffic through Cisco 3850 according to the following diagram: ![enter image description here MC source: several MC IPs such as 232.0.26.0, 232.0.27....
Gianna's user avatar
  • 11
0 votes
1 answer
310 views

What prevents a device from receiving its own multicast stream, and can it be turned off?

I know that it is normally not possible for a device to receive its own multicast stream on the same network interface where it transmitted said stream. I also understand why this is sensible, and ...
Jörg W Mittag's user avatar
2 votes
1 answer
326 views

In an IGMP V2 membership report message, isn't the destination Ethernet address based on the multicast group IP address?

Specifically, I think for this message type the Ethernet destination address always starts with 01:00:5E, followed by the second byte of the IP address masked with 0x7F, followed by the third and ...
Pat Rogers's user avatar
0 votes
1 answer
84 views

Are there broadcast/collision domains on non-Ethernet networks?

What if we have routers or hosts connected via ATM, Frame Relay, or SONET; that is, what if we have IP over SONET, IP over ATM, IP over Frame Relay, etc., do we still have broadcast domains and ...
Noob_Guy's user avatar
  • 491
3 votes
2 answers
4k views

MAC address and unicast, multicast and broadcast

I'm very new to computer networking and I'm trying to figure out this dilemma about the Unicast, Multicast and Broadcast transmissions. I was told that MAC address are unique for each device and they ...
Ludovica Stile's user avatar
14 votes
3 answers
5k views

Why isn't multicasting more popular?

Multicasting seems provide an efficient method of routing networking traffic from a source to multiple end users, especially at this moment in time with teleconferencing, streaming media, online ...
d1n037's user avatar
  • 143
1 vote
2 answers
805 views

Why does IPv6 NS not use unicast address but multicast

This is a follow up of Why not put unicast address in IPv6 packet containing NDP neighbor solicitation instead of solicited-node multicast address? The accepted answer makes no sense. It states the ...
user2984602's user avatar
2 votes
0 answers
488 views

IGMP Snooping issue. probably

I have multicast hosts that keep leaving a group, only to join back up which results in loss of video feeds. The network consists of a variety of Cisco 2960's and a Cisco 9300 w/ PIM Sparse mode set ...
Rnet's user avatar
  • 21
0 votes
0 answers
66 views

Issue with PIM-SSM Multicast Configuration ISR4431s

I have an issue with my PIM-SSM multicast configuration using ISR4431s.    I am wanting to forward broadcast data from an application from one VLAN in on the multicast source to another VLAN on a ...
Joe Hughes's user avatar
1 vote
0 answers
319 views

How should OSPF work over WiFi? [closed]

I've had problems running OSPF over my WiFi network, and it seems to be related to multicast. The routers can't maintain a neighbor relationship, and when I watch the packet traffic I see one router ...
Brent Baccala's user avatar
0 votes
1 answer
257 views

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 ...
Einheri's user avatar
  • 183
2 votes
2 answers
217 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 ...
Andreas's user avatar
  • 125
0 votes
1 answer
1k 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 |...
Hooplator15's user avatar
4 votes
4 answers
1k 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 ...
rakeshdn's user avatar
2 votes
2 answers
4k 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 ...
Finlay Weber's user avatar

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