The last-member query interval is the maximum amount of time between group-specific query messages, including those sent in response to leave-group messages. You can configure this interval to change the amount of time it takes a routing device to detect the loss of the last member of a group. When the routing device that is serving as the querier receives a leave-group message from a host, the routing device sends multiple group-specific queries to the group being left.
The querier sends a specific number of these queries at a specific interval. The number of queries sent is called the last-member query count. The interval at which the queries are sent is called the last-member query interval. Because both settings are configurable, you can adjust the leave latency. The IGMP leave latency is the time between a request to leave a multicast group and the receipt of the last byte of data for the multicast group. You can configure a subsecond interval up to one digit to the right of the decimal point.
The configurable range is 0. You can configure the last-member query count by configuring the robustness variable. The two are always equal.
Help us improve your experience. Let us know what you think. Do you have time for a two-minute survey? Maybe Later. To modify this interval:.In this post we will quickly discuss the use of most commonly needed IGMP timers. First, as we know, multicast routers periodically query hosts on a segment.
The hosts on the segment are supposed to report their group membership in response to the queries. Note that IGMPv2 defines special report suppression procedure, which allows host to suppress its own report, if it saw some other host reporting the same group. The query-interval timer is also used to define the amount of time a router will store particular IGMP state if it does not hear any reports on the group. This interval is 3x query-time and it was the only mechanism available in IGMPv1 to expire a non-needed group.
By default the interval is 60 seconds. From what we said above follows that hosts must respond to a query during some time-window interval. This time window is specified in IGMPv2 packets using special field that defines the maximum response time. You set the value of this field using the command:. When a host receives the query packet, it starts counting to a random value, less that the maximum response time.
When this timer expires, host replies with a report, provided that no other host has responded yet. This accomplishes two purposes:. Naturally, the maximum response timer could not be less than the query-interval. Note that IGMPv1 does not support the maximum response time field in its packets, and this timer is fixed to 10 seconds with version 1.
The next important timer, pertaining to IGMPv2, is last member query interval. This interval is configured using the following command:. This means that at least one host wants to leave the group. After router receives the Leave report, it checks that the interface is not configured for IGMP Immediate Leave single-host on the segment and if not, it sends out an out-of-sequence query.
The maximum-response-time in this query is set to last-member-query-interval which is ms by default. The router sends out maximum of.
Modifying the IGMP Query Response Interval
The whole procedure controls if there are any more members left on the interface. After the last query send router waits some additional time, approximately 0,5 second to finally remove the group. Then the router will treat these groups as having single host member. After the reception of a Leave message, the router immediately removes the multicast forwarding state. The last interesting timer is.
Petr Lapukhov has more than 12 years of experience working with Cisco Systems products. Petr works with all of the technologies covered within his four CCIE tracks on a daily basis, staying current with any changes in the industry. He has also received his Cisco Certified Design Expert CCDE certification, joining a small group of distinguished individuals who have achieved this status. You may contact Petr Lapukhov at petr ine.
Our staff is looking forward to assisting you!The query response interval is the maximum amount of time that can elapse between when the querier router sends a host-query message and when it receives a response from a host.
Configuring this interval allows you to adjust the burst peaks of IGMP messages on the subnet. Set a larger interval to make the traffic less bursty. Bursty traffic refers to an uneven pattern of data transmission: sometimes a very high data transmission rate, whereas at other times a very low data transmission rate.
The query response interval, the host-query interval, and the robustness variable are related in that they are all variables that are used to calculate the group membership timeout. The group membership timeout is the number of seconds that must pass before a multicast router determines that no more members of a host group exist on a subnet.
If no reports are received for a particular group before the group membership timeout has expired, the routing device stops forwarding remotely originated multicast packets for that group onto the attached network. You can configure a subsecond interval up to one digit to the right of the decimal point.
The configurable range is 0. Help us improve your experience. Let us know what you think. Do you have time for a two-minute survey?
Maybe Later. To modify the query response interval:.By examining snooping IGMP membership report messages from interested hosts, multicast traffic is limited to the subset of VLAN interfaces on which the hosts reside. The IGMP snooping software responds to topology change notifications. The term snooping is used because Layer 3 control plane packets are intercepted and influence Layer 2 forwarding decisions. Although not all features of an earlier version of IGMP are supported, the features related to membership query and membership report messages are supported for all IGMP versions.
It does not support snooping based on the source MAC address or on proxy reports. Both IGMPv1 and IGMPv2 support membership report suppression, which means that if two hosts on the same subnet want to receive multicast data for the same group, then the host that receives a member report from the other host suppresses sending its report. Membership report suppression occurs for hosts that share a port.
The fast leave feature does not send last member query messages to hosts. As soon as the software receives an IGMP leave message, the software stops forwarding multicast data to that port. IGMPv1 does not provide an explicit IGMP leave message, so the software must rely on the membership message timeout to indicate that no hosts remain that want to receive multicast data for a particular group. Note Cisco NX-OS ignores the configuration of last member query interval when you enable the fast leave feature because it does not check for remaining hosts.
By default, the software tracks hosts on each VLAN port. The explicit tracking feature provides a fast leave mechanism. Because every IGMPv3 host sends membership reports, a report suppression feature limits the amount of traffic the switch sends to other multicast capable routers. The proxy feature builds group state from membership reports from the downstream hosts and generates membership reports in response to queries from upstream queriers.
Even though the IGMPv3 membership reports provide a full accounting of group members on a LAN segment, when the last host leaves, the software sends a membership query. You can configure the parameter last member query interval.
Cisco Nexus 5000 Series NX-OS Software Configuration Guide
If no host responds before the timeout, the software removes the group state. When a host connected to the switch wants to join an IP multicast group, it sends an unsolicited IGMP join message, specifying the IP multicast group to join.
Network Engineering Stack Exchange is a question and answer site for network engineers. It only takes a minute to sign up. What adverse effects could occurred if I set the igmp snooping querier query-interval to 1 second in the switch? IGMP is between a host and a router, not a switch. Set to 1 one second would result in a broadcast storm as every multicast capable device answers the query.
Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Asked 4 years, 4 months ago. Active 2 years, 1 month ago. Viewed times. The default in switch is 60 seconds.
Hendrik Hendrik 13 3 3 bronze badges. Active Oldest Votes. Decreasing the query interval could needlessly increase the traffic on your LAN segment.
IGMP queries are between a router and the hosts.
The switch would normally be ignorant of IGMP, but IGMP snooping allows the switch to snoop on the queries so that it can send multicasts to only those switch ports which have hosts actually listening for those multicasts. Normally, a switch would flood multicasts to all ports.
Thanks for your reply ron. I still have not understand it clearly, So without a router, is a host could get the multicast traffic send from the multicast source? I'm currently facing issue for the implementation of IPTV.
When a host in my case is android setopbox with igmp support just recently boot up, the host couldn't play the IPTV channel.I am trying to set up Multicast communication for Shure audio devices on the network. Vlan68 is up, line protocol is up Internet address is Global IGMP switch querier status admin state : Enabled admin version : 2 source IP address : 0.
Vlan IGMP switch querier status elected querier is Buy or Renew. Find A Community. We're here for you! Turn on suggestions. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
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Showing results for. Search instead for. Did you mean:. Sakun Sharma. Some outputs: sh ip igmp inter vla 68 Vlan68 is up, line protocol is up Internet address is Labels: Other Collaboration Topics. Everyone's tags 4. Tags: igmp. Latest Contents. Created by kathyMill on AM. We are always looking for new topics to cover in our training to improve customer learning.
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Cisco IOS IP Multicast Command Reference
Related Content. Follow our Social Media Channels.Your software release may not support all the features documented in this module.
For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module. Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www. An account on Cisco. Multicast traffic becomes flooded because a device usually learns MAC addresses by looking into the source address field of all the frames that it receives.
A multicast MAC address is never used as the source address for a packet. Such addresses do not appear in the MAC address table, and the device has no method for learning them.
An EVC is an end-to-end representation of a single instance of a Layer 2 service being offered by a provider. In the Cisco EVC framework, bridge domains are made up of one or more Layer 2 interfaces known as service instances. A service instance is the instantiation of an EVC on a given port on a given device.
A service instance is associated with a bridge domain based on the configuration. Each bridge domain represents a Layer 2 broadcast domain. The bridge domain interface creates one entry per subnet in the Layer 2 forwarding table for each Layer 2 multicast group from which it receives an IGMP join request.
All hosts interested in this multicast traffic send IGMP join requests and are added to the forwarding table entry. During a Layer 2 lookup on a bridge domain to which the bridge domain interface belongs, the bridge domain forwards the packets to the correct EFP.
When the bridge domain interface hears the IGMP Leave group message from a host, it removes the table entry of the host. Layer 2 multicast groups learned through IGMP snooping are dynamic. However, you can statically configure Layer 2 multicast groups. If you specify group membership for a multicast group address statically, your static setting supersedes any automatic manipulation by IGMP snooping.
Multicast group membership lists can consist of both user-defined and IGMP snooping-learned-settings. Optional Enables device to send TCN query solicitation even if it is not the spanning-tree root. The default is 2 milliseconds. Optional Configures the length of time after which the group record is deleted if no reports are received.
The default is milliseconds. When both immediate-leave processing and the query count are configured, fast-leave processing takes precedence. Optional Configures the interval for snooping query messages sent in response to receiving an IGMP leave message.IP Multicast in OVN - IGMP Snooping and Relay
The EFP and bridge domain must be previously configured. The Cisco Support and Documentation website provides online resources to download documentation, software, and tools.
Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco. The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train.
Unless noted otherwise, subsequent releases of that software release train also support that feature. The following commands were introduced or modified: ip igmp snoopingip igmp snooping checkip igmp snooping explicit-track ing limitip igmp snooping immediate leaveip igmp snooping last-member-query countip igmp snooping last-member-query intervalip igmp snooping report-suppressionip igmp snooping robustness-variableip igmp snooping staticip igmp snooping tcn flood if-srvip igmp snooping tcn flood queryip igmp snooping tcn flood query solicitrouter guard ip multicast efps.
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