我有一个直接连接到我的 ISP 调制解调器的 Cisco 2621XM。我在路由器的第二个接口上有一台计算机。

拓扑：

ISP -> Modem -> Cisco Router -> Computer

当我在我的计算机上运行速度测试时，我得到 30/10。当我将计算机直接连接到调制解调器时，得到 100/10。我还有另一个 Cisco 路由器 871。同样的结果，当我将计算机连接到它时，我得到 30/10。

我开始认为这是路由器内置的默认设置？这是我的配置：

version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
enable secret 5 <REMOVED>
!
no aaa new-model
!
resource policy
!
no network-clock-participate slot 1
no network-clock-participate wic 0
ip subnet-zero
ip cef
!
no ip dhcp use vrf connected
ip dhcp excluded-address 10.4.4.1 10.4.4.100
!
ip dhcp pool ALL_ACCESS
   network 10.4.4.0 255.255.255.0
   dns-server 8.8.8.8 8.8.4.4
   default-router 10.4.4.1
!
interface FastEthernet0/0
 ip address 10.4.4.1 255.255.255.0
 ip nat inside
 speed 100
 full-duplex
!
interface Serial0/0
 no ip address
 shutdown
!
interface FastEthernet0/1
 ip address dhcp
 ip nat outside
 duplex auto
 speed auto
!
ip classless
!
no ip http server
no ip http secure-server
ip nat inside source list 1 interface FastEthernet0/1 overload
!
access-list 1 permit 10.4.4.0 0.0.0.255
!
control-plane
!
line con 0
 logging synchronous
line aux 0
line vty 0 4
 login
line vty 5 181
 login
!
end

输出show interface：

Router#sh interfaces FastEthernet0/1
FastEthernet0/1 is up, line protocol is up
  Hardware is AmdFE, address is 000e.3836.ff41 (bia 000e.3836.ff41)
  Internet address is xxx.xxx.xxx.xxx/xx
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 1/75/128247/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 51000 bits/sec, 41 packets/sec
  5 minute output rate 4000 bits/sec, 6 packets/sec
     16778657 packets input, 2855708480 bytes
     Received 5967982 broadcasts, 0 runts, 0 giants, 0 throttles
     69379 input errors, 0 CRC, 0 frame, 15274 overrun, 54105 ignored
     0 watchdog
     0 input packets with dribble condition detected
     3231581 packets output, 590804149 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 babbles, 0 late collision, 0 deferred
     484 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

sh interfaces FastEthernet0/1 status - 不输出任何东西