Chapter 20. Static Multicast Arp - Lenovo RackSwitch G8264CS Application Manual

Chapter 20. Static Multicast ARP

© Copyright Lenovo 2017
The Microsoft Windows operating system includes Network Load Balancing
(NLB) technology that helps to balance incoming IP traffic among multi‐node
clusters. In multicast mode, NLB uses a shared multicast MAC address with a
unicast IP address. Since the address resolution protocol (ARP) can map an IP
address to only one MAC address, port, and VLAN, the packet reaches only one of
the servers (the one attached to the port on which the ARP was learnt).
To avoid the ARP resolution, you must create a static ARP entry with multicast
MAC address. You must also specify the list of ports through which the multicast
packet must be sent out from the gateway or Layer 2/Layer 3 node.
With these configurations, a packet with a unicast IPv4 destination address and
multicast MAC address can be sent out as per the multicast MAC address
configuration. NLB maps the unicast IP address and multicast MAC address as
follows:
Cluster multicast MAC address: 03‐BF‐W‐X‐Y‐Z; where W.X.Y.Z is the cluster
unicast IP address.
You must configure the static multicast ARP entry only at the Layer 2/Layer 3 or
Router node, and not at the Layer 2‐only node.
Lenovo Enterprise Network Operating System supports a maximum of 20 static
multicast ARP entries. When the ARP table is full, an error message appears in the
syslog.
Note: If you use the ACL profile, an ACL entry is consumed for each Static
Multicast ARP entry that you configure. Hence, you can configure a maximum of
896 ACLs and multicast MAC entries together when using the ACL profile.The
ACL entries have a higher priority. In the default profile, the number of static
multicast ARP entries that you configure does not affect the total number of ACL
entries.
Chapter 20: Static Multicast ARP
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