In computer networking, multicast is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source. Copies are automatically created in other network elements, such as routers, but only when the topology of the network requires ...
20
votes
4answers
522 views
Pushing Large Files to 500+ Computers
I work with a team to manage 500-600 rented Windows 7 computers for an annual conference. We have a large amount of data that needs to be synced to these computers, up to 1 TiB. The computers are ...
15
votes
2answers
12k views
What is the difference between unicast, anycast, broadcast and multicast traffic?
I have never had the privilege of working in an environment that required complicated routing or if it did require it, it was handled upstream of me. I've always used very simple static routing ...
10
votes
5answers
8k views
Tools to test multicast routing
I am looking for a good simple tool that runs on a standard OS (Windows or Linux) that I can used to test that multicast is being passed properly by a router.
I have been asked by a client to enable ...
10
votes
4answers
783 views
How common are dropped packets in communications within a data center?
Let's say I have 2 machines in the same data center but not necessarily in the same rack.
How common would dropped packets be when sent using UDP between these two machines?
I'm asking under the ...
10
votes
6answers
8k views
Linux Kernel not passing through multicast UDP packets
Recently I've set up a new Ubuntu Server 10.04 and noticed my UDP server is no longer able
to see any multicast data sent to the interface, even after joining the multicast group. I've got the exact ...
9
votes
1answer
326 views
Simple Multicast Design
In order to support desktop imaging requirements I need to correct the multicast design on an existing network, but am not well versed in this subject. The diagram below gives a basic example of the ...
7
votes
5answers
566 views
Convey multicast (to another LAN) through WAN disabling multicast
My Server and Client softwares run both on Linux.
The Server broadcasts multicast, the Client listens multicast.
My Client has to migrate to another site,
and unfortunately multicast is not allowed ...
6
votes
1answer
1k views
Multicast hostname lookups on OSX
I have a problem with hostname lookups on my OSX computer. According to Apple's HK3473 document it says for v10.6:
Host names that contain only one label in addition to local, for example ...
5
votes
4answers
672 views
Is IPv6 multicast routable over the Internet?
As I understand it, public IPv6 addresses allocated by the IANA will have the prefix 2000::/3. These ip addresses will be routable through the Internet.
IPv6 multicast addresses on the other side are ...
5
votes
1answer
1k views
Why is pfSense blocking multicast traffic when it is explicitly enabled?
I have a pair of pfSense firewall/routers set up in CARP/XML Config cluster. On the LAN side, the switch also has a pair of servers running corosync/pacemaker/drbd. These are on a different ip ...
5
votes
2answers
2k views
How managed switches handle Broadcast Multicast and Unicast?
Under typical scenarios, a network switch needs to handle broadcast, multicast and unicast messages at the same time.
I'd like to understand
On a typical managed switch (1Gb Ethernet/10Gb Ethernet), ...
5
votes
1answer
75 views
Why would I ever (really) want to implement dense mode when dealing with PIM routing?
I'm introducing some PIM routing into my network to make some multicast traffic available across routers.
I have read a bit on PIM, sparse mode versus dense mode. After reading, I am trying to ...
5
votes
1answer
124 views
ntp multicast address
A silly question probably, but guess I need to ask.
If I've got four centos boxes that are acting as ntpd multicast servers, will the multicast address configured in each box's ntp.conf all be the ...
5
votes
1answer
1k views
iperf max udp multicast performance peaking at 10Mbit/s?
I'm trying to test UDP multicast throughput via iperf but it seems like it's not sending more than 10Mbit/s from my dev machine:
C:\> iperf -c 224.0.166.111 -u -T 1 -t 100 -i 1 -b 1000000000
...
4
votes
3answers
5k views
How can I test Multicast UDP connectivity between two servers?
I have a two servers on the same subnet. I have an application installed which uses Multicast UDP to propagate events between the servers and keep them in sync.
This does not seem to be happening, ...
4
votes
4answers
2k views
Multicast File Transfers
I'm looking for some multicast file transfer software. Do you have any suggestions? Must be "quickly implementable", i.e. no Tivoli or other stuff that requires a massive infrastructure. Must run on ...
4
votes
1answer
239 views
Current IP Multicast reference materials [closed]
Can anyone recommend a textbook or online resource for learning the current state of multicast technology, from the perspective of a network engineer/designer?
The 'bible' that most of my more ...
4
votes
2answers
2k views
Multicast routing across two subnets with FreeBSD 9 (Bonjour between subnets)?
I have a FreeBSD 9 router (a Soekris net6501) connected to the internet via a dsl modem (bridged), doing NAT for two internal subnets, 10.0.1.0/24 (LAN) and 10.0.2.0/24 (wifi net).
There are routes ...
4
votes
1answer
676 views
windws server 2008 udp multicast performance problem
I encounter a strange performance problem on 2008 R2 Enterprise SP1.
Here is the setup:
Many processes listening to distinct Multicast UDP streams (5 multicasts
listen by process) bound on a single ...
4
votes
1answer
164 views
Calculating and billing IP multicast usage on the Internet
I've been searching for the reasons why IP multicast isn't widely supported on the Public Internet, and a commonly-cited reason is the difficulty ISPs have in tracking Multicast usage for later ...
4
votes
2answers
895 views
Capturing multicast data with Wireshark with IGMP Snooping Enabled at the switch
I am trying to capture multicast traffic via Wireshark (actually TShark), however the switch has IGMP snooping enabled and will only send Multicast traffic on the ports that have an active IGMP ...
3
votes
11answers
2k views
Most resilient form of (private) DNS clustering?
I'm working on a setup with two datacenters linked by a MAN (bridged) and everything is doubled between them, in fail-over mode with RedHat Cluster, DRBD and that kinf of things.
I have one DNS ...
3
votes
4answers
892 views
Multicast in Rackspace cloud
On Amazon EC2, I cannot use multicast, but how about rackspace cloud? It would be very beneficial to be able to use multicast as most clustering protocols rely on it...
3
votes
4answers
4k views
Why does multicasting make the WAN inaccessible?
I'm hesitant to ask this question as I may not be able to perform the diagnostic steps to find out what is up, but:
I need to re-image a lab in a school, possibly during school hours. I am using a ...
3
votes
4answers
475 views
Is there a good way to keep IPv6 multicast packets off WiFi?
I work on a product that consists of a number of headless Linux boxes that work together as a cluster.
These boxes synchronize their state with each other by sending proprietary-format link-local IPv6 ...
3
votes
1answer
66 views
Streaming root/source in multicasting sparse mode
I'd like to verify if I understand multicasting correctly. In a pim sparse-mode configuration, the RP rtr becomes the "root" of the stream for the rest of the configured routers. Does this mean that ...
3
votes
1answer
663 views
How to monitor a UDP multicast stream on a cisco network, hopefully with SNMP
We have a LAN with 2x Cisco 4500's as gateways running HSRP.
We're using Exterity HD IP Encoders to take HD video and put it onto the network as a multicast UDP stream (playable in VLC).
I have a ...
3
votes
1answer
612 views
Multicast doesn't seem to be working on RHEL 5.5
I'm trying to install Oracle Grid Infrastructure on two machines. Their documentation states:
You must enable multicasting for the cluster on the IP address subnet ranges 224.0.0.0/24 and ...
3
votes
2answers
1k views
IGMP/Multicast routing in Linux
I need to route IGMP/Multicast traffic across two networks. I have a Linux box with two NICs, one public, one private. Need devices on the private network to flow to public. I'm pretty certain I ...
2
votes
4answers
445 views
Should a small company block multicast on their network?
Currently, the firewall at a small company is blocking multicast on their network. Should they continue to block multicast? Are there security concerns to unblocking it? Are there benefits to ...
2
votes
3answers
844 views
Why are my listener-less multicast packets affecting Wifi performance?
I've got a program that sends out a IPv6 multicast packet (to ff12::2:0:8afb:382b:c053:85f%en1) every 50ms. I've got it running on a very simple single-computer LAN (Mac mini <-wifi-> Linksys wifi ...
2
votes
2answers
184 views
MS NLB: why are multicast packets received by all servers on the LAN, not just members of the cluster
I have a MS NLB cluster (Win 2003) which includes just two hosts. The cluster is configured to use Multicast operation mode (not IGMP).
For some reason I am seeing packets intended for the NLB ...
2
votes
2answers
622 views
Can a TCP/IP be efficiently multicast among clients without UDP
I have a high bandwidth application in which a server is to be producing data a rate of ~300Mb/s on a gigabit network. Is there a way other than UDP to multicast to 1 to 10 clients through a reliable ...
2
votes
2answers
300 views
Multicast IP Addresses
I posted this on StackOverflow and was told it might be more appropriate here.
I'm having trouble understanding how multicast addresses work.
First off, is it true that if I have N clients or peers ...
2
votes
1answer
814 views
Confusion about HSRP Groups
If I have a router that has several LANs on it, and each of these LAN is attached to a second router, do I need to use different HSRP groups for each LAN?
With this set up, each virtual gateway will ...
2
votes
1answer
81 views
How does iptables determine which packets are multicast?
Are packets assumed to be multicast solely based on their ip address? I've been looking at the RFC 1112 and a quick scan doesn't appear to indicate any other flags on the ip packet.
2
votes
1answer
2k views
How do I know if IP Multicasting is enabled on my network in Windows?
How do I know if IP Multicasting is enabled on my network?
It is same question as above but for windows.
2
votes
2answers
55 views
Why would IGMP and MLD be required to forward unregistered packets to all ports?
First, a little background: My understanding is that the purpose of IGMP (and its IPv6 cousin, MLD) is to avoid wasted bandwidth by ensuring that multicast packets only get transmitted to ...
2
votes
2answers
653 views
Can I test broadcast packets on a single machine?
I want to have a server sending broadcast UDP packets and two other clients, in the same machine, receiving them. Can I do that somehow? What IP address would I use?
@gravyface gave me hope but I ...
2
votes
1answer
2k views
multicast tcpdump and subscriptions
From the multicast howto:
IP_ADD_MEMBERSHIP.
Recall that you need to tell the kernel which multicast groups you are interested
in. If no process is interested in a group, packets destined to it that ...
2
votes
1answer
299 views
What is the difference between bind, network (interface) and multicast addresses?
The DatagramSocketImpl in Java has a joinGroup method that takes a socket address (IP and PORT) plus the interface address (IP and PORT). I am trying to understand the difference and purpose of each ...
2
votes
1answer
287 views
altnet parameter into pimd.conf file
I need to route a multicast streams in my private network.
I'm using pimd for multicast routing.
The multicast routing did not work until I put altnet <multicast_source_ip> masklen 24 to the ...
2
votes
1answer
81 views
Server Unresponsive with Spike in Multicast Packets Received
I got a server from UbiquityServers about a week ago, I installed a simple Apache server and it just serves up images. The server is under very little load because it simply is an origin server behind ...
2
votes
1answer
657 views
openSUSE 11.3 multicast IGMP v2 works on one vlan, but not the other vlan
I have a server running openSUSE 11.3, with vlan5 and vlan40 configured on eth7.
I want to join two multicast IGMP v2 groups, one on vlan5 and one on vlan40.
When I send out the IGMP v2 Membership ...
2
votes
3answers
2k views
Basic multicast network performance problems
I've been using mpong from 29west's mtools package to get some basic idea of multicast latency across various Cisco switches: 1Gb 2960G, 10Gb 4900M and 10Gb Nexus N5548P. The 1Gb is just for ...
2
votes
1answer
349 views
Multicast accross the subnets
My application sends some UDP packets on a multicast address.
In our office we have 3 subnets connected via routers.
Sitting in my subnet I'm able to ping the IP of the other subnet.
Will multicast ...
2
votes
1answer
831 views
Video-on-demand/surveillance server setup
I'm planning to set up a service that would allow people to connect their ip-cameras to and watch video embedded into a website. Scheduled saving and replaying would also be available. What hardware ...
2
votes
1answer
40 views
is there a way to “multicast” a request with haproxy?
I have a configuration with a cloud of servers behind haproxy. Haproxy is loadbalancing between the servers. However there's some action that needs to be sent to each server. Currently I do it ...
2
votes
2answers
98 views
Solaris doesn't know which MAC address to use to send an UDP multicast message
I have a pair of Solaris 10 boxes which are supposed to send multicast UDP packets to a group of hosts. One of them works just fine, whereas the other one does not.
The problem with the second ...
2
votes
0answers
271 views
Turn on multicast packets in the wired LAN and keep them off the WiFi on ASUS WL-520gc router
After I enabled multicast routes on the ASUS WL-520gc router, whenever there is such multicast traffic (because TV is being watched somewhere in the wired LAN), WiFi is "dead": devices can't even ...
