NEC INTELLIGENT L2 SWITCH N8406-022A Application Manual

Also see for N8406-022A: Reference guide

Contents

NEC INTELLIGENT L2 SWITCH N8406-022A Application Manual Manual pdf 29 page image

Ports and trunking 29Statistical load distributionIn a configured trunk group containing more than one port, the load distribution is determined by informationembedded within the data frame. For IP traffic, the switch will calculate the trunk port to use for forwarding trafficby implementing the load distribution algorithm on value equals to modulus of (XOR of last 3 bits of Source and last3 bits of Destination IP address). For non-IP traffic, the switch will calculate the trunk port to use for forwardingtraffic by implementing the load distribution algorithm on value equals to modulus of (XOR of last 3 bits of Sourceand last 3 bits of Destination MAC address).Built-in fault toleranceSince each trunk group is composed of multiple physical links, the trunk group is inherently fault tolerant. As long aseven one physical link between the switches is available, the trunk remains active.Statistical load distribution is maintained whenever a link in a trunk group is lost or returned to service.Before you configure trunksWhen you create and enable a trunk, the trunk members (switch ports) take on certain settings necessary forcorrect operation of the trunking feature.Before you configure your trunk, you must consider these settings, along with specific configuration rules, asfollows:1. Read the configuration rules provided in the “Trunk group configuration rules” section.2. Determine which switch ports (up to six) are to become trunk members (the specific ports making up thetrunk).3. Ensure that the chosen switch ports are set to enabled, using the /cfg/port command.4. Trunk member ports must have the same VLAN configuration.5. Consider how the existing spanning tree will react to the new trunk configuration. See the “Spanning TreeProtocol” chapter for spanning tree group configuration guidelines.6. Consider how existing VLANs will be affected by the addition of a trunk.Trunk group configuration rulesThe trunking feature operates according to specific configuration rules. When creating trunks, consider the followingrules that determine how a trunk group reacts in any network topology:• All trunks must originate from one device, and lead to one destination device. For example, you cannotcombine a link from Server 1 and a link from Server 2 into one trunk group.• Any physical switch port can belong to only one trunk group.• Trunking must comply with Cisco® EtherChannel® technology.• All trunk member ports must be assigned to the same VLAN configuration before the trunk can be enabled.• All trunk member ports must be set to full duplex mode.• All trunk member ports must be configured for the same speed.• If you change the VLAN settings of any trunk member, you cannot apply the change until you change theVLAN settings of all trunk members.• When an active port is configured in a trunk, the port becomes a trunk member when you enable the trunkusing the /cfg/l2/trunk x/ena command. The spanning tree parameters for the port then change toreflect the new trunk settings.• All trunk members must be in the same spanning tree group and can belong to only one spanning tree group.However if all ports are tagged, then all trunk ports can belong to multiple spanning tree groups.• When a trunk is enabled, the trunk spanning tree participation setting takes precedence over that of any trunkmember.• You cannot configure a trunk member as a monitor port in a Port Mirroring configuration.• A monitor port cannot monitor trunks; however, trunk members can be monitored.