Loadbalancing DUAL ISP on Cisco ISR 4321 router

[Sankarsomasundaram]

Hi,

I have two ISP, primary line is 50 MB ILL, secondary line is 30 MB ILL connection, and also i'm using Cisco ISR4321 model router. the current configuration is primary ILL line configured in WAN0, secondary line configured in WAN1 port. and also VPN tunnel configured between two different locations, with the same Cisco ISR.

IF primary line down i have to remove unplug WAN0, then only secondary line gets wakup.

is there any possible to automatic wakup.

another one question, Is there any possible to use both bandwidth at the same time which means 50MB and 30MB at the same time.

i have to set up load balance, automatic failure line backup at the same time VPN also work.

Please advice 

Thanks 

Sankar S

[Julio E. Moisa · Accepted solution]

Hi,

If you are using BGP protocol at the edge, yes you could have load balance and use both Bandwidth at the same time. Now if you are using default static route you cannot but you can have an automatic failover, using: IP SLA, Object Track and EEM script in order to run a script once an event occurs, for example, it can delete the current default route and create other one with a different next hop (secondary ISP)

Hope it is useful

:-)

[Sankarsomasundaram · Accepted solution]

Thanks for your input.

Regards

Sankar S

[Mark Malone · Accepted solution]

Hi

Yes you can do that with ip sla tracking , track a route upstream on primary circuit when it fails ip sla will auto switch it over , you can use it in conjunction with a route-map and ip verify reachability command

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/861-cisco-router-pbr-ipsla-auto-redirect.html

[Sankarsomasundaram · Accepted solution]

Thanks for your input.
Regards
Sankar S

[Georg Pauwen · Accepted solution]

Hello,

in addition to Julio's post, IF you do use static routing, you can achieve load balancing by configuring two (three is better) static routes. Since one link is 50MB and the other is 30MB, configuring two static routes for the same 50MB link and only one for the other link, would send more traffic down the first link.

Then, if one link fails, you could use an EEM script that removes the static route(s) to the failed link, and also clear the NAT translations for faster failover.

That said, we need to see your full configuration to decide what the best solution is...

[paul driver · Accepted solution]

Hello

Another more elegant feature would to be use PER ( Performance Edge routing) with this you can utilize both links based on the primary links utilization which at a certain % set by you can then automatically begin using the secondary link.

Have a read here to see if this would be applicable to you?

res
Paul

[Joseph W. Doherty · Accepted solution]

Possible the same as what Paul has noted, Performance Routing (PfR) can dynamically load balance your two links, also in proportion to their carrying capacity. It does egress easily, ingress, through, can be complicated.

As to detecting, and rerouting, traffic due to a link outage, there are several way to do that. Generally, it often happens "automatically" if the link is seen as going down, but if the link doesn't go down, then you need some form of lost of path detection. (PfR can do that too.)

One issue with using something like PfR, you might need a feature upgrade and/or feature license to use it.