Cisco Etherchannel


Hola, os voy a mostrar como configurar Cisco Etherchannel entre dos switches Cisco, en concreto dos 2950. Lo primero enseñaros que es un Etherchannel.
Un etherchannel consiste en juntar varios puertos de u switch y hacer que funcionen como si fuera un unico puerto aumentando asi el ancho de banda. Por ejemplo, si uno con etherchannel 4 bocas de un switch a 100Mb la boca tendre un unico canal de 400Mb que si lo ponemos a FULL seran 800Mb.
Como sabeis cuando conectais dos switches entre si por mas de un cable, el protocolo Spanning-Tree se encarga de tumbar todos menos uno, con lo cual aunque tuvieramos conectados cuatro cables de switch a switch solo uno enviaria y recibiria datos, ganamos tolerancia pero no ancho de banda.
Vamos a configurar entonces un Etherchannel de cuatro puertos
SW1#configure terminal
SW1(config)#interface range fastethernet 0/5 – 8
SW1(config-if-range)#channel-group 1 mode desirable
SW2#configure terminal
SW2(config)#interface range fastethernet 0/5 – 8
SW2(config-if-range)#channel-group 1 mode desirable


Esto crea nuestro Etherchannel como vemos con un show
SW2#show interface | include line
Vlan1 is administratively down, line protocol is down
FastEthernet0/1 is down, line protocol is down (notconnect)
FastEthernet0/2 is down, line protocol is down (notconnect)
FastEthernet0/3 is down, line protocol is down (notconnect)
FastEthernet0/4 is down, line protocol is down (notconnect)
FastEthernet0/5 is up, line protocol is up (connected)
FastEthernet0/6 is up, line protocol is up (connected)
FastEthernet0/7 is up, line protocol is up (connected)
FastEthernet0/8 is up, line protocol is up (connected)
FastEthernet0/9 is down, line protocol is down (notconnect)
FastEthernet0/10 is down, line protocol is down (notconnect)
FastEthernet0/11 is down, line protocol is down (notconnect)
FastEthernet0/12 is down, line protocol is down (notconnect)
Port-channel1 is up, line protocol is up (connected)

Podemos utilizar el show etherchannel para ver el ancho de banda
SW1#show interface port-channel 1
Port-channel1 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 000a.8ab9.7e46 (bia 000a.8ab9.7e46)
MTU 1500 bytes, BW 400000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Full-duplex, 100Mb/s, media type is unknown media type
input flow-control is off, output flow-control is off
Members in this channel: Fa0/5 Fa0/6 Fa0/7 Fa0/8
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:30, output hang never
Last clearing of “show interface” counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2000 bits/sec, 4 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
140 packets input, 14252 bytes, 0 no buffer
Received 131 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 131 multicast, 0 pause input
0 input packets with dribble condition detected
37 packets output, 3791 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out