# Single/Dual Homed and Multi-homed Designs **URL:** https://forum.networklessons.com/t/single-dual-homed-and-multi-homed-designs/1545 **Category:** Lessons Discussion **Created:** [March 3, 2017, 2:47pm UTC](https://forum.networklessons.com/t/single-dual-homed-and-multi-homed-designs/1545 "2017-03-03T14:47:41Z") **Posts on this page:** 1 **Showing post:** 16
### Author: ![lagapidis](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/lagapidis/32/4949_2.png) [@lagapidis](https://forum.networklessons.com/u/lagapidis) #### Post date: [August 18, 2019, 5:31am UTC](https://forum.networklessons.com/t/single-dual-homed-and-multi-homed-designs/1545/16 "2019-08-18T05:31:32Z")
Hello Raunak There are two issues involved here. The first has to do with outgoing traffic. If your network is connected to multiple ISPs, then you have full control over which ISP will be used for outgoing traffic. This can be accomplished in several ways including IGP dynamic routing protocols such as OSPF or EIGRP, as well as gateway redundancy protocols such as HSRP. If you have BGP running on a portion of the edge of your network, you can accomplish this by adjusting BGP attributes to favour one ISP as well. Now the technical details of how you can do this depends on the method you are using. If you are using a routing protocol, you can change the metrics to prefer one ISP over the other. If you’re using HSRP, you can change the active router to the one connecting to the ISP of your choice. You can also do equal or unequal load balancing. Here are some lessons that will help you in these configurations: > **[EIGRP Unequal Cost Load Balancing](https://networklessons.com/eigrp/eigrp-unequal-cost-load-balancing)** > > EIGRP can be configured for unequal cost load balancing. You will learn how it works and how to configure it in this lesson. > **[OSPF Path Selection explained](https://networklessons.com/ospf/ospf-path-selection-explained)** > > OSPF will select a path based on the origin BEFORE looking at the cost of the path. In this lesson, I'll explain to you how it works. > **[BGP Attributes and Path Selection](https://networklessons.com/bgp/bgp-attributes-and-path-selection)** > > BGP (Border Gateway Protocol) uses an attribute list for path selection. In this lesson, you learn the BGP attributes and how BGP selects the best path. The other issue is incoming traffic, for traffic that is initiated from the outside, such as when you want to access a web server on the Enterprise from the Internet at large. This can only be achieved using BGP. You will have to use various BGP attributes to inform both ISPs of your internal IP addresses, and you can adjust these parameters in order to **influence** incoming traffic to take either the path of one ISP or another. More information on how you can do this both technically and in cooperation with your ISPs can be found at this post: > [@Cisco Campus Network Design Basics](https://forum.networklessons.com/t/cisco-campus-network-design-basics/1162/38): > > Hello AZM I order to achieve such redundancy, you will need to use BGP in a dual or multi-homed configuration. Specifically, this means that the IP addresses of your web servers must be advertised via all three ISP connections, with varying attributes to indicate which is the primary, secondary, and so on, route to get to your servers. Now there are several “administrative” issues involved here. If your public IP addresses are provided by your ISP, and you have different ISPs at each site, y… I hope this has been helpful! Laz --- _[View the full topic](https://forum.networklessons.com/t/single-dual-homed-and-multi-homed-designs/1545)._