How is an IGMP querier elected?
Querier election process: when there are two routers in the same subnet then only one of them should send query messages. The election ensures only one router becomes the active querier. The router with the lowest IP address becomes the active querier.
How is PIM Dr elected?
On a multi-access network, one of the PIM routers is elected as a Designated Router (DR). On the last hop LAN, the PIM DR is responsible for tracking local multicast listeners and forwarding traffic to these listeners if the group is operating in PIM-SM.
What is PIM Dr priority?
ip pim dr-priority DRs are responsible for encapsulating multicast data from local sources into PIM-SM register messages and for unicasting them to the Rendezvous Point. The router with the highest priority wins the DR election.
What is PIM in router?
Protocol Independent Multicast (PIM) is a collection of multicast routing protocols, each optimized for a different environment. PIM control messages are sent as raw IP datagrams (protocol number 103), either multicast to the link-local ALL PIM ROUTERS multicast group, or unicast to a specific destination.
Which router is elected the IGMP querier when more than one router is in the same LAN segment?
If there are multiple queriers (routers) on the subnet, a designated router (DR) is elected using PIM to avoid sending duplicate multicast packets. The elected querier is the router with the highest IP address.
How a querier is selected in IGMPv2?
When an IGMPv2 router receives a General Query message, the election of IGMPv2 Querier starts by comparing the source IP address in the message with its own interface address. The router having the lowest IP address on the subnet will be elected the IGMP Querier.
What is PIM assert?
Assert Messages contain the metric of the unicast route to the source in question, the Administrative Distance of the protocol that discovered the route, the multicast source and the group itself, and are used to elect what is called the PIM Forwarder.
How does PIM Sparse Mode work?
PIM Sparse Mode uses an explicit request approach, where a router has to ask for the multicast feed with a PIM Join message. PIM Sparse Mode is indicated when you need more precise control, especially when you have large volumes of IP multicast traffic compared to your bandwidth.
What is the difference between IGMP and PIM?
IGMP snooping allows a device to only forward multicast streams to the links on which they have been requested. PIM Sparse mode requires specific designated routers to receive notification of all streams destined to specific ranges of multicast addresses.
Why do we need IGMP querier?
The responsibility of the Querier is to send out IGMP group membership queries on a timed interval, to retrieve IGMP membership reports from active members, and to allow updating of the group membership tables.
What is the difference between the Dr and the IGMP querier?
The DR and the IGMP querier are selected based on different criteria and may be different devices on the same subnet. The DR is the device with the highest IP address on the subnet, whereas the IGMP querier is the device with the lowest IP address. Query messages are used to elect the IGMP querier as follows:
How to elect the DR on a PIM network?
To elect the DR,each PIM router on the network examines the receive Hello messages and compare its IP address with those neighbors. The router with the highest IP address is the DR In the following diagram: Does the DR main tasks are the following:
How does IGMP work with multiple multicast receivers?
If more than one multicast receiver exists for the same multicast group, only one of these hosts sends an IGMP report message; the other hosts suppress their report messages. In IGMPv1, there is no election of an IGMP querier. If more than one device on the segment exists, all the devices send periodic IGMP queries.
What is the Pim Dr and Pim forwarder for Shared tree?
if multiple multicast routers are present on the LAN segment with default settings one acts as the PIM DR and the one other one as the IGMP querier. The PIM forwarder concept is specially important in PIM bidirectional. for shared tree the PIM assert competiotion happens using a source the RP address.
