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VLANs and LAGs
When Ethernet interfaces are added to a LAG, they are removed from all
existing VLAN membership and take on the VLAN membership of the LAG.
When members are removed from a LAG, the members regain the Ethernet
interface VLAN membership as per the configuration.
LAG Thresholds
In many implementations, a LAG is declared as up if any one of its member
ports is active. This enhancement provides configurability for the minimum
number of member links to be active to declare a LAG up. Network
administrators can also utilize this feature to automatically declare a LAG
down when only some of the links have failed.
LAG Hashing
The purpose of link aggregation is to increase bandwidth between two
switches. It is achieved by aggregating multiple ports in one logical group. A
common problem of port channels is the possibility of changing packets order
in a particular TCP session. The resolution of this problem is correct selection
of an Ethernet port within the port channel for transmitting the packet to
keep the original packet order.
The hashing algorithm is configurable for each LAG. Typically, an
administrator is able to choose from hash algorithms utilizing the following
attributes of a packet to determine the outgoing port:
•
Source MAC, VLAN, EtherType, and incoming port associated with the
packet.
•
Source IP and Source TCP/UDP fields of the packet.
•
Destination MAC, VLAN, EtherType, and incoming port associated with
the packet.
•
Source MAC, Destination MAC, VLAN, EtherType, and incoming port
associated with the packet.
•
Destination IP and Destination TCP/UDP Port fields of the packet.
•
Source/Destination MAC, VLAN, EtherType, and incoming port
associated with the packet.
Layer 2 Switching Commands
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