Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Router C2811 with 4 ADSL lines

Hi everybody.

We've got a customer with a router C2811 for his Internet access. It has 4 ADSL links, with the same ISP. The summary of the configuration is:

ADSL1 - interface ATM0/0/0.1 - fixed ip address

ADSL2 - interface ATM0/1/0.1 - fixed ip address

ADSL3 - interface ATM0/2/0.1 - fixed ip address

ADSL4 - interface ATM0/3/0.1 - fixed ip address

ip cef

ip route 0.0.0.0 0.0.0.0 ATM0/0/0.1

ip route 0.0.0.0 0.0.0.0 ATM0/1/0.1

ip route 0.0.0.0 0.0.0.0 ATM0/2/0.1

ip route 0.0.0.0 0.0.0.0 ATM0/3/0.1

ip nat inside source route-map adsl1 interface ATM0/0/0.1 overload

ip nat inside source route-map adsl2 interface ATM0/1/0.1 overload

ip nat inside source route-map adsl3 interface ATM0/2/0.1 overload

ip nat inside source route-map adsl4 interface ATM0/3/0.1 overload

!

ip access-list extended NAT_1

permit ip 192.168.100.0 0.0.0.255 any

route-map adsl2 permit 10

match ip address NAT_1

match interface ATM0/1/0.1

!

route-map adsl3 permit 10

match ip address NAT_1

match interface ATM0/2/0.1

!

route-map adsl1 permit 10

match ip address NAT_1

match interface ATM0/0/0.1

!

route-map adsl4 permit 10

match ip address NAT_1

match interface ATM0/3/0.1

!

We realized that web browsing was very slow and then we figured out that the problem was DNS traffic. With wireshark we observed that it was many more DNS requests than DNS responses.

So we created a default route for all traffic to public DNS servers were routed by the adsl1 and it worked perfectly:

ip route 80.58.0.33 255.255.255.255 ATM0/0/0.1

ip route 80.58.61.250 255.255.255.255 ATM0/0/0.1

ip route 194.224.52.36 255.255.255.255 ATM0/0/0.1

Which can be an explanation for that? The rest of traffic is load balanced correctly, why cannot be the same for DNS traffic?

Thank you very much, Juan.

406
Views
0
Helpful
0
Replies
CreatePlease login to create content