I am trying to do a bit of planning and would like some clarification.

Will the overall network speed be degraded when the default gateway port speed is only 100Mbps?

For instance. Our network has a MPLS router that has a port speed of 100Mbps set as the default gateway for that office. That location does also have a 1Gbps and 10Gbps fiber connection connecting other offices together.

Can someone point me in the correct direction of a diagram of how packet traffic flows across/through the default gateway and the network? Does an initial packet hit the default gateway to get the route and then all following packets understand the route the first packet took after the default gateway?


9/30/2014 The picture below is an overview of the network. The SBN network in the upper right hand corner is all one VLAN. That network is all flat and nothing special. All end users and servers are on the same VLAN and subnet. That location as well as all of the other locations get their internet piped through the the Metronet device. (This Metronet is a city wide fiber ring shared among several businesses in the area. We do not manage the routers that deal with that network) All of our servers are currently in the SBN office and will soon be moving over to our new location at the MC office in the upper left corner of the diagram.

The GAP location is a shared datacenter space we have that is setup in bridged mode with our SBN location. The default gateway for the SBN and GAP locations is the 100Mbps MPLS router labeled GAP MPLS. There is a 1Gbps fiber link between the SBN and GAP locations.

We use the MPLS devices for phone and some specialized data. The ASA and Comcast devices are setup to connect the offices for the rest of their data needs to the SBN/GAP office.

We are looking into transitioning the GAP SW25 switch to a better layer 3 switch and do some of our own routing on that device instead of the MPLS router that we do not manage.

Network Overview

  • 1
    Do the fiber connections use the same MPLS router? A simple diagram would be helpful.
    – Ron Trunk
    Sep 29, 2014 at 21:34
  • Without a diagram, it's tough to determine what will be impacted. Generally, if you have multiple VLANs in a switched infrastructure, it's a bad idea to have your default gateway for those VLANs be on an upstream device ("router on a stick") and not on the core or distro layers themselves. Sep 29, 2014 at 23:00
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 10, 2017 at 15:37

3 Answers 3


There are many things you can to do improve the manageability and reliability of your network. I would start with breaking up the large and geographically diverse layer 2 network ( into smaller layer 3 subnets and route between. But to answer your specific question, if the traffic flows through the MPLS router to the WAN network, then the interface speed may be a factor, depending on the WAN bandwidth. But if traffic goes through one of the firewalls, then the MPLS router should issue a redirect to the host so it will send traffic directly to the firewall. In that case the router is not involved in the traffic flow.


Not long after posting this we ditched the MPLS and re-configured the core network switch to be the default gateway for the network. This did several things for us:

  • Removed the bottleneck of using our providers equipment for the default gateway
  • Removed equipment that was not 1Gb from the network
  • Gave us complete control over internal routing

We are soon to be splitting the bridge network from one of our locations to the datacenter and making them two separate L3 networks.


Will the overall network speed be degraded when the default gateway port speed is only 100Mbps?

Depends on the current traffic capacity. As i understood from your explanation you have 2 modes for connecting both locations.

  1. via dedicated bw
  2. via MPLS

You need to carefully monitor the current traffic utilization to see how much you route via MPLS.

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