Redundant ISP connection through VWIC

[M Talha]

Dear All,

I am looking for a solution where i can connect my Cisco router 2821 through a second ISP in case primary link goes down. The router has vwic-2mft-g703 installed. So is it possible to have second ISP connecting on this module so that i have redundancy on my network ?

Regards,

Talha

[Georg Pauwen · Accepted solution]

Hello,

the VWIC-2MFT-G703 has two E1 ports, so redundancy is definitely possible. As for the configuration, it depends on how you connect to the ISPs. With e.g. BGP, you could configure load balancing/failover, with e.g. static routes you could achieve the same.

[M Talha]

Thank you so much for replying. I will be using static route for backup ISP link. Now i want that if my primary link goes down the secondary link automatically takes over so the users wont have to face internet connectivity issue. What should i do for that ? Hope to have your reply soon. Please share any web links to configure E1 as backup link.

[Georg Pauwen]

Hello,

you could use IP SLA to track the availability of your primary link. If the ping to 8.8.8.8 (the Google DNS server in this example) fails, the connection to the secondary link will be activated.

Of course this is just an example. If you post the full configuration of your 2821, I can add the necessary bits.

----------

interface Vlan 10

ip address 172.16.1.1 255.255.255.0

ip nat inside

interface Serial0/0:1
ip address 10.0.0.1 255.255.255.0

ip nat outside
!
interface Serial0/1:1
ip address 10.0.0.2 255.255.255.0

ip nat outside

!
ip nat inside source route-map PRIMARY interface Serial0/0:1 overload
ip nat inside source route-map BACKUP interface Serial0/1:1 overload
ip route 0.0.0.0 0.0.0.0 Serial0/0:1 track 1
ip route 0.0.0.0 0.0.0.0 Serial0/1:1 10
!
access-list 10 permit 172.16.1.0 0.0.0.255
!
ip sla 1
icmp-echo 8.8.8.8 interface Serial0/0:1
timeout 150
frequency 2
ip sla schedule 1 life forever start-time now
!
track 1 ip sla 1 reachability
!
route-map PRIMARY permit 1
match ip address 10
match interface Serial0/0:1
!
route-map BACKUP permit 1
match ip address 10
match interface Serial0/1:1

[M Talha]

Thank you so much for your response, much appreciated. I am sharing the configuration. kindly add the necessary configuration.

[Georg Pauwen]

Hello Muhammad,

thanks for the config. One question: you have the following configured:

interface GigabitEthernet0/1
description *** CORE SWITCH ***
ip address 10.1.10.18 255.255.255.0
ip nat outside
ip virtual-reassembly
duplex auto
speed 100
!
interface Serial0/0/0:0
description
ip address 221.X.X.14 255.255.255.252
ip virtual-reassembly
load-interval 30
no fair-queue
!
interface Serial0/0/1:0
ip address 172.16.1.1 255.255.255.252
ip nat outside
ip virtual-reassembly
load-interval 30
no fair-queue

There is no further NAT configured, is that on purpose ?  Also, are the two ISPs going to be connected to Serial0/0/0:0 and  Serial0/0/0:1 ? 

[M Talha]

interface Serial0/0/0:0
description
ip address 221.X.X.14 255.255.255.252
ip virtual-reassembly
load-interval 30
no fair-queue
!
interface Serial0/0/1:0
ip address 172.16.1.1 255.255.255.252
ip nat outside
ip virtual-reassembly
load-interval 30
no fair-queue

i am currently not using these interfaces, secondly the two interfaces that are in use -- int gig0/1 and the other int gig0/3/0(ISP). I have configured NAT on firewall so such things configured here.

[Georg Pauwen]

Hello Muhammad,

so the firewall is directly connected to an ISP ? The configuration sample I have posted works for one router directly connected to two different ISPs, which does not seem to reflect your setup. Can you post a schematic drawing of how your devices are physically connected ?