以太网交换机常用的光模块有SFP，GBIC，XFP，XENPAK。它们的英文全称，中文名不常用，可以简单了解下:
SFP: Small Form-factor Pluggable transceiver ，小封装可插拔收发器
GBIC ：GigaBit Interface Converter，千兆以太网接口转换器
XFP: 10-Gigabit   small Form-factor Pluggable transceiver   万兆以太网接口小封装可插拔收发器
XENPAK:   10 Gigabit EtherNet Transceiver PAcKage万兆以太网接口收发器集合封装
通过diplay interface命令可以在软件中显示光模块的端口类型信息，显示格式为:
dis interface GigabitEthernet 3/1/1
GigabitEthernet3/1/1 current state : UP
IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 000f-e231-76fc
The Maximum Transmit Unit is 1500
Media type is optical fiber, loopback not set
Port hardware type is 1000_BASE_SX_MMF
1000Mbps-speed mode, full-duplex mode
Link speed type is autonegotiation, link duplex type is autonegotiation
Flow-control is not enabled
The Maximum Frame Length is 1552
Broadcast MAX-ratio: 50%
Allow jumbo frame to pass
PVID: 2
Link-status hold interval:3 Sec
Port link-type: access
Tagged   VLAN ID : none
Untagged VLAN ID : 2
Last 300 seconds input: 26839 packets/sec 131978872 bits/sec     13%
Last 300 seconds output: 29370 packets/sec 134850992 bits/sec     13%
Input(total): 11445215469 packets, 7408683268701 bytes
         - broadcasts, - multicasts
Input(normal): 11445215469 packets, 7408683268701 bytes
         0 broadcasts, 189412 multicasts
Input: 0 input errors, 0 runts, 0 giants, 0 throttles, 0 CRC
         0 frame, 0 overruns, - aborts, 0 ignored, - parity errors
Output(total): 12586012561 packets, 7697511630034 bytes
         - broadcasts, - multicasts, 0 pauses
Output(normal): 12586012561 packets, 7697511630034 bytes
         259 broadcasts, 191785 multicasts, 0 pauses
Output: 0 output errors, - underruns, - buffer failures
         0 aborts, 0 deferred, - collisions, 0 late collisions
         - lost carrier, - no carrier
Receive Packet Peak Value Info: 148254344 bits/sec, happened at 15:05:34 10-31-2007
Transmit Packet Peak Value Info: 138774616 bits/sec, happened at 13:05:52 10-31-2007
1000_BASE_SX_MMF 各字段含义如下：
1000 光模块支持的最高速率
SX    ：传输距离。（SX 短距。LX 中距 LH+传输距离 长距）