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New Member

Dual ISP connectivity

ISP A-> 2Mbps link terminated at 36XX router with IP block XX.XX.XX.XX

ISP B-> 2Mbps link terminated at Juniper M20 router with IP block YY.YY.YY.YY

My plan is hook webservers behind above two WAN links.

Requirement: WAN links must work as loadsharing and redundant.

Do I need to run BGP? and what range of IP addresses must be assigned to servers( either of ISP A or ISP B ).

Please comment on this.



Re: Dual ISP connectivity

You would require your own ip subnet as the IP block of one ISP will not be allowed inside the other ISP domain & vice cersa.

If you have your own IP address you would need to run BGP and use maximum paths command.



Re: Dual ISP connectivity


will you please clear some detail... first of all tell us you want to infulance incoming and outgoing both the traffice...

and talking about loadbalancing you can have other option of VRRP as you are using cisco and juniper combination... and also you need to consider the stetfull as well as stetless failover with the help of NAT also for your server...

and your loadbalncing also depens on you network design also... hows you vlan and other IP addressing schem deployed in your network... that will also play important role in you network...

its more better to use static nat for the server... instad of using the global ip address to the server...

ofcourse BGP is the great for that...



Re: Dual ISP connectivity


Well, No doubt BGP will solve you issue here. There also few other options that we can consider here to achieve the load-balancing.

Please paste a network diagram of your connectivity to the internet and we will be able to tell you the things more clearly.

-amit singh

New Member

Re: Dual ISP connectivity


with the 2 ISP?s you should speak EBGP; between your routers IBGP.

So you can influence the outgoing traffic of setting the local preference.

The incomin traffic depends of how your ISP announce you to the internet. Setting prepends you can increase the AS-PAth.

When one link fails, BGP routes all the traffic on the other link.

You can assign IPs from ispA and from ispB to your servers.



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