cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
4429
Views
3
Helpful
2
Replies

Dual ISP Multihoming, IP NAT & DNS

delano1981
Level 1
Level 1

Good Day,

I'm trying to accomplish the following on my Cisco 1841 Router;

Dual ISP Multihoming - I want to be able to route traffic through ISP A and if ISP A goes down I want to re-route traffic through ISP B. I think I've got this part all sorted out... So its just the latter that I'm having problems with.

Web Browsing on ISP B - As an addition to the above... I want to be able to send all http(s) traffic to ISP B. I'm having some issues with this.. Can someone please assist.

Additionaly is it a best practice to run DNS on this Cisco 1841? and does this router have the resources to do so... I'm tempted to use the router as a DNS server because when switching between ISP's the DNS becomes an issue. ISP A does not allow the use of ISP B DNS and vice verse.

Please see config below.

Building configuration...

Current configuration : 3003 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
!
boot-start-marker
boot-end-marker
!
logging buffered 50000

!
no aaa new-model
clock timezone Guyana -3
ip cef
!
!
no ip dhcp use vrf connected
ip dhcp excluded-address 10.10.10.1 10.10.10.10
!
ip dhcp pool testFH_Guyana
   import all
   network 10.10.10.0 255.255.255.0
      default-router 10.10.10.1
   dns-server 190.124.220.2 190.124.220.3
!
!
multilink bundle-name authenticated
!
!
archive
log config
  hidekeys
!
!
!
track 10 ip route 69.147.114.224 255.255.255.255 reachability
!
!
!
interface Loopback0
ip address 1.1.1.1 255.255.255.255
ip nat inside
ip virtual-reassembly
!
interface FastEthernet0/0
description ISP1 128Kbps Dedicated Circuit
ip address 190.108.199.64 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat outside
ip nat enable
no ip virtual-reassembly
duplex auto
speed auto
no cdp enable
!
interface FastEthernet0/1
description ISP2 512Kbps Dedicated Circuit
ip address 190.80.2.70 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip nat outside
ip nat enable
no ip virtual-reassembly
duplex auto
speed auto
no cdp enable
!
interface FastEthernet0/0/0
!
interface FastEthernet0/0/1
!
interface FastEthernet0/0/2
!
interface FastEthernet0/0/3
!
interface Vlan1
ip address 10.10.10.1 255.255.255.0
ip nat inside
ip nat enable
ip virtual-reassembly
!
no ip forward-protocol nd
ip route 0.0.0.0 0.0.0.0 190.108.199.1 track 10
ip route 0.0.0.0 0.0.0.0 190.80.2.69 10
ip route 10.0.0.0 255.0.0.0 10.10.10.0
ip route 69.147.114.224 255.255.255.255 190.108.199.1
!
!
no ip http server
ip nat inside source route-map isp1 interface FastEthernet0/0 overload
ip nat inside source route-map isp2 interface FastEthernet0/1 overload
ip nat inside source static 10.10.10.6 190.80.2.197 route-map isp2static
ip nat inside source static 10.10.10.6 190.108.199.101 route-map isp1static
!
ip sla 10
icmp-echo 69.147.114.224
timeout 1000
frequency 5
ip sla schedule 10 life forever start-time now
access-list 100 permit ip 10.10.10.0 0.0.0.255 any
no cdp run
route-map isp2static permit 10
match interface FastEthernet0/1
!
route-map isp1static permit 10
match interface FastEthernet0/0
!
route-map isp2 permit 10
match ip address 100
match interface FastEthernet0/1
!
route-map isp1 permit 10
match ip address 100
match interface FastEthernet0/0
!
!
!
control-plane
!
banner motd ^C UnAuthorized Users STAY OUT ^C
!
line con 0
password 7 0968093E181C13175A555C7B
logging synchronous
login
line aux 0
line vty 0 4
exec-timeout 5 0
logging synchronous
login
transport input telnet
!
scheduler allocate 20000 1000
end

2 Replies 2

sean_evershed
Level 7
Level 7

The following Optimised Edge Routing config example for two ISPs should help. It is using two IP SLA configs, one for each ISP.

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_configuration_example09186a00808d2b72.shtml

As for DNS you could point your PCs to one or more public DNS servers, eg Google.

http://code.google.com/speed/public-dns/

Please rate all posts that are helpful.

Thanks for the DNS info... but the config for load balancing does not allow me to choose a more-desirable connection over a less-desirable connection, which is what i required as well as to route all tcp 80 traffic through the alternate interface.

Review Cisco Networking for a $25 gift card