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BGP/ WAN Load Balancing and Redundancy + Allternatives

Calling all Cisco experts ….

I’m looking for any advice and recommendations for a couple of my customers who are looking for High Availability for their Internet Edge.  They don’t have their own CIDR block but do have multiple ISPs.  I was thinking they could apply for their own /24 and pursue BGP peering with their providers  but would imagine they just aren’t handing out /24s anymore.  Does anyone know what the minimum requirements providers are looking for to allow BGP advertisements?  I’m also curious as to what router at a minimum would be recommended.  I’m thinking the 2900 ISR G2s could probably handle a full BGP table with enough memory.

I was also wondering if anyone of you have seen IPv6 being deployed anywhere between smaller customers and ISPs or anywhere in general. 

With internet access being so cheap a lot of people have multiple providers, but I don’t know of any other solution to provide redundancy other than the primary/backup ISP capabilities on the ASA/ link state tracking etc.  That can really only provide outbound redundancy since they usually have their web presence using the provider assigned IPs from their primary connection.  I have also seen some people using basic Load Balancing Solutions ( Barracuda ) that can do some nice things with DNS fairly cheap to provide resiliency that way.  But if there is a similar Cisco solution I would rather push that.

Thank you,


  • WAN Routing and Switching

Re: BGP/ WAN Load Balancing and Redundancy + Allternatives


For BGP peering you need a router (not an ASA).
Depending on the amount of routes that the router is supposed to handle you can use a relative small router or you need a high-end
router to be able to handle the entire Internet routing table.

If these are remote sites, they could just use a default gateway to the Internet and some specific routes if talking BGP.
I have not seen IPv6 widely deployed, though all equipment is IPv6-capable now, it's not fully in use as of yet.

For high availability and redundancy you can talk BGP to your ISPs, enable HSRP, VRRP or GLBP on your routers and Failover on the
ASAs and the tracking feature.

I would say, that it depends on the amount of remote sites, the kind of traffic passing through the links and the type of redundancy
that you're looking for (performance against budget), you can design a very stable network.


New Member

Re: BGP/ WAN Load Balancing and Redundancy + Allternatives

Federico, I appreciate the quick response.

If I have one customer who has three internet connetions each to different ISPs, and wants to Load Share/ Balance traffic inbound to applications hosted on their servers and provide Redundancy, is BGP the only answer?  I'm also curious as to if they need to obtain their own IPv4 address space and ASN.

Also, If you know of any alternatives to BGP provided by Cisco for this type of topology please let me know.

Thanks again!


Re: BGP/ WAN Load Balancing and Redundancy + Allternatives

I would say BGP is the preferred way in terms of talking the the ISPs.

Using BGP you can manipulate incoming traffic because you can exchange routing information between one or multiple ISPs.

Normally, your organization will have one ASN and you will peer with three ASN if having three ISPs.

The ISP will give you the public block of IPs, and you can use a private scheme on the local network.

You will use the public blocks to manipulate the routing so that traffic enter and leave in the way you like.


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