Sometimes your system may display the message “Troubleshooting Linux Multicast”. This problem can be caused by a number of reasons.
I was looking for a lightweight tool to help me troubleshoot multicast on a VXLAN transport network (document). vCNS and NSX have built-in tools (pings of all sizes and broadcastspackets) which is a little more flexible where I can record any IGMP connection and output.
CentOS virtual machine with interface directly to Exchange network and SMCRoute software. The link contains this important binary package that runs on RHEL / CentOS. Some other notes:
If you have multiple interfaces, make sure the multicast passes through the most appropriate one: route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
I also had to install the glibc package:
yum -y glibc install.i686
Make sure the multicast core is
cat works with / boot / config- | grep CONFIG_IP_MULTICAST
Enable ICMP ECHO for Broadcast / Multicast
sysctl net.ipv4.icmp_echo_ignore_broadcasts = 0
Start by starting the smcroute daemon: smcroute -d
Use the -j and -l group commands to join and exit a multicast: smcroute -j eth0 239.0.0.1 smcroute -l eth0 239.0.0.1
To view hosts as well as members of a specific IGMP group, just check the connection with them and see who is responsible:
[root @ CentOS ~] # ping 239.1.0.10 PING 239.1.0.10 (239.1.0.10) 56 (84) data bytes. 64 bytes at the beginning of 1.1.0.1: icmp_seq = 1 ttl = 64 time = 0.141 ms At 64 bytes from 1.1.0.3: icmp_seq = 1 ttl = 64 time = 0.256 Microsoft Windows (DUP!)
Hosts 1.1.0.1 and 1.1.0.3 responded to ping 239 from multicast group 1.0.10.
This chapter contains suggestions for troubleshooting IP multicast configuration issues. With IP multicasting, WebLogic Server instances in each cluster can share one IP address and one port number. This capability allows all cluster members to be designed as a single unit and provides automatic communication between cluster parts.
For general information on using and configuring multicastin the cluster see Cluster And design config.xml.
For more information on configuring a multicast address to match the console, see the “Cluster: Configuration: Multicast” section in the Oracle Weblogic Administration Console Server Online Help.
For general cluster troubleshooting suggestions, see Chapter 14, Troubleshooting Common Problems.
Check Multicast Address And Port Configuration
The first step in troubleshooting multicast issues is to verify that you can securely access the configured multicast port and address. The multicast address must be compiled correctly for each cluster.
Problems with multicast and port alignment are some of the most common reasons why a cluster won’t join or start collecting data. Remember the following when using multicast addresses:
The multicast address must be an IP address between 224.0.0.0 and 239.255.255.255 or an organization namewith an IP address in this range.
By default, WebLogic Server 239 uses the multicast address 192.0.0.
Do not use all x.0.0.1 multicast addresses where x is in the range 7 through 9, inclusive.
Possible Errors
The following types, as well as errors, often occur due to multicast issues:
Multicast socket could not be created during socket clustering
Multicast error
Error capturing multicast socket
Check Multicast Address And Port
To check all multicast addresses and ports, do one of the following:
Check the cluster multicast address and even the port using the WebLogic Server Administrator Console.
Check the influencer information in config.xml using multicast.
Identify Network Configuration Problems
After verifying that the multicast address and port are generally configured correctly, determine if the network has multicast issues
Physical Connections
Check the online connection of each computer hosted by the support team in the cluster.
Make sure all network components, including the router’s DNS and help desk, are connected and working properly.
Address Conflicts
Use the netstat utility to check if other resources on the cellular network are using a multicast address.
Make sure each computer has a specific IP address.
Nsswitch.conf Settings For UNIX Systems
The UnkownHostExceptions error can occur on UNIX systems. This error can happen by accident, even if the server is not only heavily loaded. Check /etc/nsswitch.conf and improve the order to avoid 'files, dns, nis' before this error appears.
For more information, see your system’s nsswitch.conf page.
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After verifying that the multicast address connector is configured correctly and that there are probably no physical or config issues Guided by your network, you can use utils.MulticastTest to verify that multicast is working and what to do. Find out if multicast works. unwanted traffic exists between clusters.
For instructions on using MulticastTest, see multicasttest “Using Oracle WebLogic Server Java Utilities” in the Oracle WebLogic Server Command Reference.
If MulticastTest fails and the engine is multihomed, make sure to use the primary address. See Multicast machines as well as multihomed.
You must set -Djava.net.preferIPv4Stack = true when displaying the IPv4 address format for a multicast address on Linux machines with dual IPv4 / IPv6 stacks.
Define Multicast Functions
The following sections describe how to configure the various features of the server’s web logic to work with multicast. Waiting time
Multicast
Multicast Timeouts Can Now Occur During NIC Failover. Timeouts Can Cause Error In New GoodTheir News, For Example:
Timed Out
Disable NIC Failover.
I Would Disable The Igmp Snooping Switch. This Switch Is A Component Of The Internet Group Management Protocol (IGMP) And Is Used To Prevent Torrent Multicast Problems On The Managed Switch.
Check The IGMP Level On Windows 2003 To Ensure That Multicast Packets Are Supported.
Set Multicast Lifetime To:
Multicast TTL = 32
For More Information, See Configuring Time To Live (TTL) Multicast.
Cluster Heartbeat
Each WebLogic Server event in the cluster uses multicast to send a regular heartbeat message announcing its availability. By monitoring heartbeat messages, the instance servers running in the cluster determine when the server hosting the instance has exited ands building.
For possible help with cluster heart rate problems, see the sections.
Use the “ifconfig” payload to check if multicast is already enabled for an IP address. # ifconfig eth0 | grep -i multi-ply UP BROADCAST RUNNING MULTICAST MTU: 1500 Metric: 1.How to disable multicast on a specific IP / interface:To support multicast on a specific IP / interface:
Step by step tiny multicast using the mtrace command.mstat.Ring.Displays the number of routes of the IP address.ip mroute is active.Debug internet packages.
To really make sure that multicast is working correctly on your network, you can use the important quick test tcpdump / ping. If the multicast is working fine, you should see packets arriving at the first node. Now repeat this process on each node to check if multicast is working on your network.
