DELL 8132 ユーザーズマニュアル

Port Channel Commands

Trunking, which is also called Port Channels or Link Aggregation, is initiated 

and maintained by the periodic exchanges of Link Aggregation Control PDUs 

(LACPDUs). 
From a system perspective, a LAG is treated as a physical port. A LAG and a 

physical port use the same configuration parameters for administrative 

enable/disable, port priority, and path cost. When a physical port is 

configured as part of a LAG, it no longer participates in forwarding operations 

until the LAG becomes active.
A LAG failure of one or more of the links stops traffic on the failed link. Upon 

failure, the flows mapped to a link are dynamically reassigned to the 

remaining links of the LAG. Similarly when links are added to a LAG, the 

conversations may need to be shifted to a new link.

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 a physical port within the port channel for transmitting the packet to keep 

original packets 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. 

2CSPC4.X8100-SWUM102.book  Page 613  Friday, March 15, 2013  8:56 AM