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Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
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Chapter 7 Configuring the Switch Ports
Creating EtherChannel Port Groups
In
Figure 7-1
, a port group of two workstations communicates with a router.
Because the router is a single-MAC-address device, source-based forwarding
ensures that the switch uses all available bandwidth to the router. The router is
configured for destination-based forwarding because the large number of stations
ensures that the traffic is evenly distributed through the port-group ports on the
router.
Figure 7-1
Source-Based Forwarding
The switch treats the port group as a single logical port; therefore, when you
create a port group, the switch uses the configuration of the first port for all ports
added to the group. If you add a port and change the forwarding method, it
changes the forwarding for all ports in the group. After the group is created,
changing STP or VLAN membership parameters for one port in the group
automatically changes the parameters for all ports. Each port group has one port
that carries all unknown multicast, broadcast, and STP packets.
Port Group Restrictions on Static-Address Forwarding
The following restrictions apply to entering static addresses that are forwarded to
port groups:
•
If the port group forwards based on the source MAC address (the default),
configure the static address to forward to all ports in the group. This method
eliminates the chance of lost packets.
•
If the port group forwards based on the destination address, configure the
static address to forward to only one port in the port group. This method
avoids the possible transmission of duplicate packets. For more information,
see the
“Adding Static Addresses” section on page 6-59
.
FEC port group
12650
Source-based
forwarding
Destination-based
forwarding
Cisco router
Catalyst 2900 XL
or Catalyst 3500 XL switch