How exactly does peering at an IXP lower my bandwidth bill?

Question

I run a small gaming community and our monthly transit bill from our ISP is getting pretty high due to all the traffic between our users. I've been reading that connecting to an Internet Exchange Point (IXP) is a primary way to reduce these costs. I get the basic idea of peering, but I'm fuzzy on the direct financial mechanics. Since the traffic is exchanged directly at the IXP instead of going through our ISP's network, does our ISP simply charge us less because they're handling less of our data? I'm trying to understand the direct cause and effect before I look into buying a port.

admin · Accepted Answer

The direct financial benefit of IXP peering is that traffic exchanged with other peers at the exchange bypasses your transit provider entirely, eliminating the cost for that data from your transit bill. Your ISP charges for transit based on the volume of data they carry for you across their network to the broader internet. When you peer at an IXP, traffic destined for other networks present at the same exchange is routed directly over the IXP's shared switch fabric, never entering your ISP's paid transit service. This directly reduces the volume counted toward your 95th percentile or committed data rate billing with your ISP. The cost model shifts from paying for all traffic via transit to a fixed fee for the IXP port and potential cross-connect, plus reduced transit costs. For example, configuring your router to prefer the IXP route for peers involves setting a higher Local Preference for routes received via your peering session:



route-map PEER-IN permit 10

 set local-preference 200

!

router bgp 65001

 neighbor 192.0.2.1 route-map PEER-IN in

The underlying concept is that you are substituting paid transit for settlement-free peering where mutually beneficial, thereby lowering your aggregate cost per megabit.

route-map PEER-IN permit 10
 set local-preference 200
!
router bgp 65001
 neighbor 192.0.2.1 route-map PEER-IN in

The underlying concept is that you are substituting paid transit for settlement-free peering where mutually beneficial, thereby lowering your aggregate cost per megabit.

How exactly does peering at an IXP lower my bandwidth bill?

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