Contents
Which address is a multicast MAC address?
The multicast MAC address is a special value that begins with 01-00-5E in hexadecimal. The remaining portion of the multicast MAC address is created by converting the lower 23 bits of the IP multicast group address into 6 hexadecimal characters.
How do I find my multicast MAC address?
For example, if the IPv4 multicast address of a group is 224.0. 1.1, the IPv4 multicast MAC address of this group is 01-00-5E-00-01-01. In an IPv6 multicast MAC address, the leftmost 16 bits are 0x3333 and the rightmost 32 bits are mapped to the rightmost 32 bits of an IPv6 multicast address.
What is multicast in NLB?
Multicast – NLB adds a layer 2 MAC address to the NIC of each node. Each NLB cluster node basically has two MAC addresses, its real one and its NLB generated address. With multicast, you can create static entries in the switch so that it sends the packets only to members of the NLB cluster.
What is the MAC address used for IPv4 multicast?
IPv4 multicast packets are delivered using the Ethernet MAC address range 01:00:5E:00:00:00 through 01:00:5E:7F:FF:FF (with an OUI owned by the IANA). This range has 23 bits of available address space.
What is the difference between Unicast and multicast in NLB?
* MS NLB supports two configurations: unicast mode, or multicast mode. Unicast mode replaces the existing MAC address of all cluster members with a new cluster MAC address, which is shared by all nodes. Multicast mode adds the cluster MAC address to the node adapter, but also leaves the original one.
What is multicast MAC address used for?
Ethernet MAC Multicast addresses allow a source device to send a packet to a group of devices. Devices that belong to a multicast group are assigned a multicast group IP address. The range of IPv4 multicast addresses is 224.0. 0.0 to 239.255.
What happens to MAC address in multicast NLB?
When Network Load Balancing (NLB) is operating in multicast mode, the Network Load Balancing (NLB) cluster’s Media Access Control (MAC) address is assigned to the server’s Network Interface Card (NIC) and the card’s permanently burned MAC address is also maintained so that both MAC addresses can be used.
What’s the difference between multicast and source MAC addresses?
Then it looks in its MAC address table to see it it has an interface for the destination address. Multicast is s special form of broadcast, and a multicast MAC address is only a destination MAC address. A host sending a frame will use its own MAC address as the source address, not a multicast address.
Why does the NLB cluster use the Bf MAC address?
So, to summarize, each client connecting to the NLB cluster will use the bf MAC address as the destination which causes the switches to flood all ports with the traffic. Each NLB node sends data using the priority number instead of bf to stop the switch from learning the bf MAC address and trying to map it to a single port.
Is it good or bad to use NLB unicast mode?
NLB unicast mode works differently. From a network perspective, it’s the worst option. By using bogus MAC addresses (treated as unknown unicast), it forces a switch to act like a hub. The only “good” thing is, that no extra configuration is needed on network devices.