Ip Address Forwarding - Cisco Catalyst 2960 series Configuration Manual

Information About EtherChannels
load-balancing, packets from different hosts use different ports in the channel, but packets from the same host
use the same port in the channel.
With destination-MAC address forwarding, when packets are forwarded to an EtherChannel, they are distributed
across the ports in the channel based on the destination host's MAC address of the incoming packet. Therefore,
packets to the same destination are forwarded over the same port, and packets to a different destination are
sent on a different port in the channel.
With source-and-destination MAC address forwarding, when packets are forwarded to an EtherChannel, they
are distributed across the ports in the channel based on both the source and destination MAC addresses. This
forwarding method, a combination source-MAC and destination-MAC address forwarding methods of load
distribution, can be used if it is not clear whether source-MAC or destination-MAC address forwarding is
better suited on a particular switch. With source-and-destination MAC-address forwarding, packets sent from
host A to host B, host A to host C, and host C to host B could all use different ports in the channel.
Related Topics
Configuring EtherChannel Load-Balancing
EtherChannel Configuration Guidelines, on page 338
Layer 2 EtherChannel Configuration Guidelines, on page 340
Default EtherChannel Configuration, on page 337

IP Address Forwarding

With source-IP address-based forwarding, packets are distributed across the ports in the EtherChannel based
on the source-IP address of the incoming packet. To provide load balancing, packets from different IP addresses
use different ports in the channel, and packets from the same IP address use the same port in the channel.
With destination-IP address-based forwarding, packets are distributed across the ports in the EtherChannel
based on the destination-IP address of the incoming packet. To provide load balancing, packets from the same
IP source address sent to different IP destination addresses could be sent on different ports in the channel.
Packets sent from different source IP addresses to the same destination IP address are always sent on the same
port in the channel.
With source-and-destination IP address-based forwarding, packets are distributed across the ports in the
EtherChannel based on both the source and destination IP addresses of the incoming packet. This forwarding
method, a combination of source-IP and destination-IP address-based forwarding, can be used if it is not clear
whether source-IP or destination-IP address-based forwarding is better suited on a particular switch. In this
method, packets sent from the IP address A to IP address B, from IP address A to IP address C, and from IP
address C to IP address B could all use different ports in the channel.
Related Topics
Configuring EtherChannel Load-Balancing
EtherChannel Configuration Guidelines, on page 338
Layer 2 EtherChannel Configuration Guidelines, on page 340
Default EtherChannel Configuration, on page 337
Load-Balancing Advantages
Different load-balancing methods have different advantages, and the choice of a particular load-balancing
method should be based on the position of the switch in the network and the kind of traffic that needs to be
load-distributed.
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
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