Hello, this is my first post and I have been banging my head against a wall for days trying to figure out this issue. I have a Cisco 1841 running the latest ROMMON 12.4(13r)T5 and IOS ADVIPSERVICESK9-M 15.1(4)M6. Via CLI (I'm studying for CCNA and despise GUIs anyway) I have configured a basic single NAT'd, DHCP setup. Topology: {ISP} --> {Motorola SB6141} --> Fa0/0 {Cisco 1841} Fa0/1 --> {My Mac}. For the internetwork, all connections are Cat5E/Cat6. I know that the 1841 is not a powerful device, but that in ideal situations it should be able to support 38 Mbps or 4.75 MBps.
Situation: When the SB6141 is plugged directly into my Mac, I see the rated throughput of 50/10 Mbps. When the 1841 enters the equation, I only get 1.4 MB/s up and down. What I've tried: SB6141 doesn't have a way of configuring it AFAIK, but the Fa0/0 port it connects to is set to auto speed and auto duplex. A sh int fa0/0 shows that it has negotiated full-duplex and 100Mb/s. Fa0/1 is auto speed and auto duplex and in either topology it negotiates to full-duplex and 100Mb/s. I have tried manually setting both interfaces to full/100 and that made no difference. When a download hits the 1.4 MB/s mark, brief or sustained, the sh cpu process history for the 1841 shows that it is maxing out at 100%. I have OSPF running, but I had the same issue prior to incorporating that. Here is my config:
Elway#sh run
Building configuration...
Current configuration : 2033 bytes
!
! Last configuration change at 21:34:11 UTC Fri Jan 31 2014 by XXX
version 15.1
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Elway
!
boot-start-marker
boot-end-marker
!
!
!
no aaa new-model
!
dot11 syslog
no ip source-route
!
!
ip dhcp excluded-address 10.0.24.1 10.0.24.50
!
ip dhcp pool mileHIGH
import all
network 10.0.24.0 255.255.255.0
default-router 10.0.24.1
dns-server 75.75.75.75 75.75.76.76
!
!
!
ip cef
ip domain name XXX
ip name-server 75.75.75.75
ip name-server 75.75.76.76
ip name-server 8.8.8.8
no ipv6 cef
!
multilink bundle-name authenticated
!
crypto pki token default removal timeout 0
!
!
!
!
license udi pid CISCO1841 sn FTX0905W15R
archive
log config
hidekeys
username XXX privilege 15 secret 4 XXX
!
redundancy
!
!
ip tcp synwait-time 10
!
!
!
!
!
!
!
interface FastEthernet0/0
description Comcast-Link
ip address dhcp
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip flow egress
ip nat outside
ip virtual-reassembly in
no ip route-cache
ip tcp adjust-mss 1452
duplex auto
speed auto
no cdp enable
!
interface FastEthernet0/1
description LAN
ip address 10.0.24.1 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip flow egress
ip nat inside
ip virtual-reassembly in
no ip route-cache
duplex auto
speed auto
!
interface Serial0/0/0
no ip address
shutdown
no fair-queue
!
interface Serial0/1/0
no ip address
shutdown
!
router ospf 1
network 10.0.24.0 0.0.0.255 area 0
!
ip forward-protocol nd
ip http server
no ip http secure-server
!
!
ip nat inside source list 1 interface FastEthernet0/0 overload
!
access-list 1 permit 10.0.24.0 0.0.0.255
!
!
!
!
!
!
control-plane
!
!
!
line con 0
exec-timeout 0 0
logging synchronous
login local
line aux 0
line vty 0 4
login local
transport input ssh
line vty 5 15
login local
transport input ssh
!
scheduler allocate 20000 1000
end
