Cisco 3560G 48TS Software Configuration Guide - Page 594

LACP Modes, LACP Interaction with Other Features, Load Balancing and Forwarding Methods

Page 594 highlights

Understanding EtherChannels Chapter 29 Configuring EtherChannels LACP Modes Table 29-2 shows the user-configurable EtherChannel LACP modes for the channel-group interface configuration command. Table 29-2 EtherChannel LACP Modes Mode active passive on Description Places a port into an active negotiating state in which the port starts negotiations with other ports by sending LACP packets. Places a port into a passive negotiating state in which the port responds to LACP packets that it receives, but does not start LACP packet negotiation. This setting minimizes the transmission of LACP packets. Forces a port to channel without PAgP or LACP. With the on mode, a usable EtherChannel exists only when a port group in the on mode is connected to another port group in the on mode. Both the active and passive LACP modes enable ports to negotiate with partner ports to an EtherChannel based on criteria such as port speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers. Ports can form an EtherChannel when they are in different LACP modes as long as the modes are compatible. For example: • A port in the active mode can form an EtherChannel with another port that is in the active or passive mode. • A port in the passive mode cannot form an EtherChannel with another port that is also in the passive mode because neither port starts LACP negotiation. LACP Interaction with Other Features The DTP and the CDP send and receive packets over the physical ports in the EtherChannel. Trunk ports send and receive LACP PDUs on the lowest numbered VLAN. In Layer 2 EtherChannels, the first port in the channel that comes up provides its MAC address to the EtherChannel. If this port is removed from the bundle, one of the remaining ports in the bundle provides its MAC address to the EtherChannel. LACP sends and receives LACP PDUs only from ports that are up and have LACP enabled for the active or passive mode. Load Balancing and Forwarding Methods EtherChannel balances the traffic load across the links in a channel by reducing part of the binary pattern formed from the addresses in the frame to a numerical value that selects one of the links in the channel. EtherChannel load balancing can use MAC addresses or IP addresses, source or destination addresses, or both source and destination addresses. The selected mode applies to all EtherChannels configured on the switch. You configure the load balancing and forwarding method by using the port-channel load-balance global configuration command. 29-6 Catalyst 3560 Switch Software Configuration Guide 78-16156-01

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29-6
Catalyst 3560 Switch Software Configuration Guide
78-16156-01
Chapter 29
Configuring EtherChannels
Understanding EtherChannels
LACP Modes
Table 29-2
shows the user-configurable EtherChannel LACP modes for the
channel-group
interface
configuration command.
Both the
active
and
passive
LACP
modes enable ports to negotiate with partner ports to an EtherChannel
based on criteria such as port speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers.
Ports can form an EtherChannel when they are in different LACP modes as long as the modes are
compatible. For example:
A port in the
active
mode can form an EtherChannel with another port that is in the
active
or
passive
mode.
A port in the
passive
mode cannot form an EtherChannel with another port that is also in the
passive
mode because neither port starts LACP negotiation.
LACP Interaction with Other Features
The DTP and the CDP send and receive packets over the physical ports in the EtherChannel. Trunk ports
send and receive LACP PDUs on the lowest numbered VLAN.
In Layer 2 EtherChannels, the first port in the channel that comes up provides its MAC address to the
EtherChannel. If this port is removed from the bundle, one of the remaining ports in the bundle provides
its MAC address to the EtherChannel.
LACP sends and receives LACP PDUs only from ports that are up and have LACP enabled for the active
or passive mode.
Load Balancing and Forwarding Methods
EtherChannel balances the traffic load across the links in a channel by reducing part of the binary pattern
formed from the addresses in the frame to a numerical value that selects one of the links in the channel.
EtherChannel load balancing can use MAC addresses or IP addresses, source or destination addresses,
or both source and destination addresses. The selected mode applies to all EtherChannels configured on
the switch. You configure the load balancing and forwarding method by using the
port-channel
load-balance
global configuration command.
Table 29-2
EtherChannel LACP Modes
Mode
Description
active
Places a port into an active negotiating state in which the port starts negotiations with other
ports by sending LACP packets.
passive
Places a port into a passive negotiating state in which the port responds to LACP packets
that it receives, but does not start LACP packet negotiation. This setting minimizes the
transmission of LACP packets.
on
Forces a port to channel without PAgP or LACP. With the
on
mode, a usable EtherChannel
exists only when a port group in the
on
mode is connected to another port group in the
on
mode.