I have 4 different WAN links for redundancy one of them is 15mbps MPLS and the other ones are 30mbps Internet , 50 mbps Internet and 10 mbps MPLS , the way that it is set up is that we have load balancing across the 4 links with TINA (Traffic Intelligence over IPSEC) , now the primary link is the MPLS link because of lower latency that it offers , and secondary is the 50 mbps and both load balance the traffice sent out , now the problem and question is the following there are occassions where the link of of the 15mbps gets saturated the interfaces that connects the mpls router and my equipment are both 1Gig interfaces but since the bandwidth provided by ISP is 15mbps, and I'm trying to understand if there is a way that the interface of the ISP router can let my interface know that its limit is 15mbps ?

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    Research the term QoS. Depending on your router model, you can certainly configure the interfaces to shape traffic to the specified speed, and you can give priority to certain traffic classes that you can define. The big vendors, e.g. Cisco and Juniper, have some very extensive QoS support.
    – Ron Maupin
    Nov 10, 2019 at 16:45
  • Thank you Ron , I have some knowledge of QoS I definetly need more , in this case I was wondering if there a was a way like the windowing process for interfaces to inform about their forwarding limit , I dont if that makes sense . But seems like there isnt
    – Kejimire
    Nov 10, 2019 at 17:25
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    The thing is that your WAN link bandwidth is not dynamic. You order a particular speed, so you can configure QoS for that speed on that interface. If you order a speed upgrade for the interface, then you just change the configuration. There really is no way for the carrier equipment to inform your equipment about the speed that it is limiting to (usually just policing traffic above the rate you buy).
    – Ron Maupin
    Nov 10, 2019 at 17:29

1 Answer 1


There is no interface rate that runs at precisely 15 Mbit/s. The most common handover interface is Ethernet which exists for 10, 100, 1000 Mbit/s or faster.

Your plan's data rate is implemented as the forwarding rate of the router, possibly by the ISP uplink's data rate (between CPE and COE) or a software limitation. That is of no consequence to you, however.

The router simply doesn't transport packets that exceed these limits but queues them or drops them when the queue is filled up.

  • Thank you for your response Zac , I know there is not interface rate that runs at precisly at 15Mbit/s , why I would like to know if there is a way that at the software level per say , the COE can let the CPE known some how of its forwarding rate , in order for the CPE to understand to stop sending traffic across that link and start using any of the other links that I have?
    – Kejimire
    Nov 10, 2019 at 14:18
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    @Kejimire You mean between CPE and your router, don't you? There is no standard way of doing that. You can consult your data plan or ask the ISP and then configure a WAN interface limit on your router, so the CPE's buffer doesn't bloat (that much) and you can improve traffic shaping or balancing.
    – Zac67
    Nov 10, 2019 at 14:42

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