27-2
Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 27 Configuring EtherChannels
Unders tanding Ether Channels
Figure 27-1 Typical EtherChannel Configuration
Each Et h erCha nne l ca n co ns is t of up to eigh t com pa tib ly configur ed Ethe rn et i nte rface s. A ll in te rface s
in ea ch E ther Cha nn el must be the same spe ed, an d all mu st b e c onfigured a s L aye r 2 int erfac es .
Note Th e net work device to w hic h you r switc h is c onn ect ed c an im pose i ts own limit s on t he nu mbe r of
interfaces in th e EtherC hannel . For Catalyst 2950 swi tches, the num ber of Ethe rCha nnels is limi ted to
six with ei ght po rts per Et herCh ann el.
If a link within an EtherChannel fails, traffic previously carried over that failed link changes to the
remaining links within the EtherChannel. A trap is sent for a failure, identifying the switch, the
EtherChannel, and the failed link. Inbound broadcast and multicast packets on one link in an
Ether Channe l a re b loc ked f rom re turnin g o n a ny othe r link of the E the rChann el.

Understanding Port-Channel Interfaces

When you create an EtherChannel for Layer 2 interfaces, a logical interface is dynamically created. You
then manually assign an interface to the EtherChannel by using the channel-group interface
configurati on comma nd as shown in Figure 27-2.
Each EtherChannel has a logical port-channel interface numbered from 1 to. 6.
Catalyst 8500, 6000,
5500, or 4000
series switch
Catalyst 3550-12T
switch
Gigabit EtherChannel
Catalyst 3550-12T
switch
Workstations
10/100
Switched
links
74618
Catalyst 2950G-24
switch
Workstations
10/100
Switched
links
1000BASE-X 1000BASE-X