Cisco 1841 Slow Web Browsing

T

timberdoodle

Gawd
Joined
Sep 22, 2008
Messages
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I aquired an 1841 recently from work. I am trying to use it as my home router. I have set it up with the very basics (dhcp wan, dhcp pool for lan, nat). It is grabbing an address from Comcast. It works, ran speedtest and the speed looks fine at 25/3 or so.

The problem is when I am surfing the net. I'll go to a site like Youtube. It will take forever to load the site, never play the video. I have tried other sites, Autoblog, Break, etc. It seems like anything with a lot of multimedia. If I go to MSN, the first time it will take about 10 seconds to load all the pictures, after that it is instant (probably cached).

Then, if I wait a few minutes, go back to the same site, sometimes it'll be just as slow, sometimes it'll work fine. I have checked a few of the cisco logs and it doesn't show any drops or errors that I can see. If I run a constant ping to something like google.com while it is slow loading, the response time remains normal around 25ms.

I set up my other d-link home router and it works fine with all sites, same speeds from speedtest. I tried plugging a computer directly into the Cisco and same slowness issues.

Any suggestions?
 
Need to see your inside and outside interface configurations at a minimum. I get like 35/6 through my 1841 with no issues.
 
1841 I get 98/98 ish on my 100Mbps leased line but its not doing any firewalling

At home my 1841 is doing IOS firewalling etc and its fine but thats on 13/1 ADSL

I would check for a duplex issue first and post up your config.
 
Using 960 out of 196600 bytes
!
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
!
!
no aaa new-model
!
resource policy
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
ip subnet-zero
ip cef
!
!
no ip dhcp use vrf connected
ip dhcp excluded-address 192.168.0.1
!
ip dhcp pool Home_Clients
import all
network 192.168.0.0 255.255.255.0
default-router 192.168.0.1
!
!
!
!
!
!
interface FastEthernet0/0
ip address dhcp
ip nat outside
duplex auto
speed auto
!
interface FastEthernet0/1
ip address 192.168.0.1 255.255.255.0
ip nat inside
duplex auto
speed auto
!
ip classless
ip route 0.0.0.0 0.0.0.0 FastEthernet0/0
!
ip http server
ip nat inside source list 101 interface FastEthernet0/0 overload
!
access-list 101 permit ip 192.168.0.0 0.0.0.255 any
!
control-plane
!
!
line con 0
line aux 0
line vty 0 4
login
!
end
 
it picks up the comcast one using dhcp on fe0/0

I manually set a client to 4.2.2.2 but same result.

Is there any reason to be concerned about the getting a dhcp address from Comcast or should I set a default gateway for a next hop? I have heard mix reviews on using dhcp on a cisco in this configuration.
 
well your dhcp isn't handing out DNS... you should change it to this:

Code: 
ip dhcp pool Home_Clients
   import all
   network 192.168.0.0 255.255.255.0
   default-router 192.168.0.1
   dns-server 75.75.75.75 75.75.76.76
You don't need the static default route since you are getting your default route in the DHCP lease from Comcast

That and you have absolutely no security configured at all.

There's nothing "screwy" with using DHCP for IP address assignment on a router.
 
Watch the exclusion of the gateway of the last resort or default gateway command (ip route 0.0.0.0 0.0.0.0). This command is not needed for dynamic public IP address assignment via DHCP since that's the whole point of using DHCP. In other words, the default gateway should appear in routing table due to DHCP process with the ISP and not by manual configuration.

The only time you need to manually configure the default gateway using DHCP is when you need to change the route administrative distance into something that fits your need. Should this be your choice, the command is the following.
ip route 0.0.0.0 0.0.0.0 dhcp [ENTER NEW ADMINISTRATIVE DISTANCE HERE]
 
mattjw916 said:
well your dhcp isn't handing out DNS... you should change it to this:

Code: 
ip dhcp pool Home_Clients
   import all
   network 192.168.0.0 255.255.255.0
   default-router 192.168.0.1
   dns-server 75.75.75.75 75.75.76.76
You don't need the static default route since you are getting your default route in the DHCP lease from Comcast

That and you have absolutely no security configured at all.

There's nothing "screwy" with using DHCP for IP address assignment on a router.
Click to expand...

This should block ICMP by default I would assume. Is there anything else I need to take into consideration for security?
 
mattjw916 said:
well your dhcp isn't handing out DNS... you should change it to this:

Code: 
ip dhcp pool Home_Clients
   import all
   network 192.168.0.0 255.255.255.0
   default-router 192.168.0.1
   dns-server 75.75.75.75 75.75.76.76
You don't need the static default route since you are getting your default route in the DHCP lease from Comcast

That and you have absolutely no security configured at all.

There's nothing "screwy" with using DHCP for IP address assignment on a router.
Click to expand...

Import all should grab his ISP's DNS.
 
Hi,

If I was to have basic firewall and NAT (port forward for torrents etc) can the 1841 do 100Mbps ?

This is for DOCSIS 3.0 cable internet.

Thanks,
K.

Jay_oasis said:
1841 I get 98/98 ish on my 100Mbps leased line but its not doing any firewalling

At home my 1841 is doing IOS firewalling etc and its fine but thats on 13/1 ADSL

I would check for a duplex issue first and post up your config.
Click to expand...
 
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