Questions tagged [multicast]
For questions about multicast communications and protocols.
228
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15
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PIM-DM forwarding state expiry timer
I've recently read rfc 3973 - PIM-DM and there are a lot of timers explained but I couldn't find any information on the forwarding state expiry timer.
(172.45.1.15, 239.1.1.11), 00:00:06/**00:02:53**, ...
- 119
0
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1
answer
36
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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 ...
- 119
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15
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In multicast, do shared trees exist solely to reduce router processing of (S,G) forwarding states?
I am asking this question strictly at a conceptual level. I am not asking from a specific protocol's standpoint.
Why do shared trees exist in multicast routing? What was the reasoning behind them?
...
- 119
1
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1
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30
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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 ...
- 119
5
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2
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408
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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 ...
- 119
1
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1
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34
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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, ...
- 11
1
vote
1
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58
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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 ...
- 11
0
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1
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60
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IPv6-over-IEEE802.15.4 Multicast scope
An IPv6 Multicast address is defined as
| 8 | 4 | 4 | 112 bits |
+--------+----+----+-------------------------------------+
|11111111|flgs|scop| group ID ...
0
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1
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49
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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(...
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3
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1
answer
52
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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 ...
- 165
0
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2
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241
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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 ...
- 356
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1
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124
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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: ...
- 356
1
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0
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56
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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 ...
- 121
3
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1
answer
266
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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 ...
- 321
2
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1
answer
377
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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. ...
- 127
1
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1
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159
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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,...
- 125
2
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3
answers
443
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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 ...
- 356
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2
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294
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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 ...
- 356
1
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1
answer
232
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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 ...
- 63
2
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0
answers
50
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 = ...
- 1,325
0
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1
answer
80
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 ...
- 1,325
2
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2
answers
283
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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 ...
- 49
1
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1
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70
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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 ...
- 113
1
vote
1
answer
907
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 ...
- 111
0
votes
3
answers
162
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 ...
- 107
0
votes
1
answer
114
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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-...
- 1,075
0
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0
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69
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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 ...
- 1
0
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55
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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? ...
- 317
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1
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654
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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 ...
1
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0
answers
264
views
Multicast traffic through Cisco3850
I have a test scenario and trying to pass multicast traffic through Cisco 3850 according to the following diagram:
- 11
0
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1
answer
115
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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 ...
- 650
2
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1
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159
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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 ...
- 23
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1
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59
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 ...
- 451
2
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2
answers
2k
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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 ...
12
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3
answers
4k
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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 ...
- 123
1
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2
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389
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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 ...
- 13
2
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0
answers
328
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 ...
- 21
0
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0
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48
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 ...
1
vote
0
answers
204
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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 ...
- 111
0
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1
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126
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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 ...
- 163
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2
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91
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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 ...
- 113
0
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1
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820
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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 |...
- 101
4
votes
4
answers
784
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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 ...
- 75
2
votes
2
answers
2k
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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 ...
- 137
2
votes
1
answer
90
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" ...
- 151
1
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0
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71
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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):
+---------------------------------------+
| ...
- 111
2
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1
answer
144
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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 ...
- 105
0
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2
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563
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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 ...
- 3
2
votes
2
answers
573
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 ...
- 23
5
votes
1
answer
456
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 ...
- 51