ers swapped out Because the individual links are physical, these interfaces can be shown in the same manner as any physical interface on an IOS device, via the show interface command: Switch-1-IOS# sho int g3/1 GigabitEthernet5/1 is up, line protocol is up (connected) Hardware is C6k 1000Mb 802.3, address is 0011.7f1a.791c (bia 0011.7f1a.791c) Description: Link #1 in Po1 MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Full-duplex, 1000Mb/s input flow-control is off, output flow-control is off Clock mode is auto ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:45, output 00:00:03, output hang never Last clearing of "show interface" counters 30w6d Input queue: 0/2000/1054/0 (size/max/drops/flushes) Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 924000 bits/sec, 187 packets/sec 5 minute output rate 86000 bits/sec, 70 packets/sec 190820216609 packets input, 207901078937384 bytes, 0 no buffer Received 48248427 broadcasts (1757046 multicast) 0 runts, 0 giants, 0 throttles input errors, 0 CRC, 0 frame, 1054 overrun, 0 ignored 0 watchdog, 0 multicast, 0 pause input 0 input packets with dribble condition detected 129274163672 packets output, 80449383231904 bytes, 0 underruns 0 output errors, 0 collisions, 0 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 Notice that no mention is made in the output of the fact that the interface is a mem- ber of an EtherChannel, other than in the description. This reinforces the notion that all ports should be labeled with the description command. Configuring and Managing EtherChannel CHAPTER 8 Spanning Tree The Spanning Tree Protocol (STP) is used to ensure that no layer-2 loops exist in a LAN. As you'll see in this chapter, layer-2 loops can cause havoc. Spanning tree is designed to prevent loops among bridges. A bridge is a device that connects