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New Member

BGP - multi home and dual home

Hi,

What is the difference btn multi and dual and when is it used?

4 REPLIES
New Member

Re: BGP - multi home and dual home

how do i know which one has been configured? we have links to two different ISP's at 2 different locations.

Re: BGP - multi home and dual home

I think both means the same, i.e redundantly connected to a single or multiple ISPs

Narayan

Bronze

Re: BGP - multi home and dual home

dual-homed = 2

multi-homed = 2 or more

New Member

Re: BGP - multi home and dual home

I know this post is really old but someone quoted it to me recently so I wanted to update it for accuracy and help anyone else searching for this question as it comes up in google search. This is something that a lot of people miss use. It's really good to have a clear understanding on. I've seen CCIE's get this wrong and cause major miss-understandings.

Here's a quote from the Cisco Press book:

CCNP Routing and Switching Quick Reference (642-902, 642-813, 642-832), 2nd Edition

Types of ISP Connections

A site with a single ISP connection is single-homed. This is  fine for a site that does not depend heavily on Internet or WAN  connectivity. Either use static routes, or advertise the site routes to  the ISP and receive a default route from the ISP.

A dual-homed site has two connections to the same ISP,  either from one router or two routers. One link might be primary and the  other backup, or the site might load balance over both links. Either  static or dynamic routing would work in this case.

Multihoming means connecting to more than one ISP at the  same time. It is done for redundancy and backup if one ISP fails, and  for better performance if one ISP provides a better path to frequently  used networks. This also gives you an ISP-independent solution. BGP is  typically used with multihomed connections.

You can take multihoming a step further and be dual-multihomed,  with two connections to multiple ISPs. This gives the most redundancy.  BGP is used with the ISPs and can be used internally also.

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