Router Charts

Router Charts

Router Ranker

Router Ranker

Router Chooser

Router Chooser

NAS Charts

NAS Charts

NAS Ranker

NAS Ranker

More Tools

More Tools

LAN & WAN

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15

Introduction

After our tours through port management and security, it's time to wrap up this series with a review of what a smart switch can do for bandwidth management. In the GS108T, these functions fall under the QoS tab.

Rate Control

I'll come back to the Global Configuration screen and instead skip right to where you can start ratcheting down bandwidth with minimal muss or fuss. Figure 1 shows the port-based Rate Control settings.

QoS Rate Control

Figure 1: QoS Rate Control

All you need to do is decide whether you want to control the rate of traffic coming into (Ingress Rate) or out of (Egress Rate) a port, select the desired rate from the dropdown and save the settings. The main limitation of the GS108T's rate control is that it may not be much help for limiting Internet traffic because there aren't a lot of "clicks" below 10 Mbps and only one below 1 Mbps. But if you need to limit traffic on your LAN, the settings are probably fine.

I ran a quick IxChariot test to see how smooth rate limiting was. Figure 2 starts with no limiting and then applied limits of 60, 200 and 400 Mbps. Implementations of bandwidth limiting that I have seen on previous generation smart switches and more notably in consumer routers, appeared to control bandwidth by completely turning traffic on and off and varying the ratio of "on" and "off" time. In contrast, the GS108T's rate limiting looks very smooth.

Rate limiting in action
Click to enlarge image

Figure 2: Rate limiting in action

Note that because a smart switch is a Layer 2 device, it can't rate limit specific services such as BitTorrent, FTP, etc. and it also can't rate limit by IP address. Rate limiting works only by physical port and all traffic through that port.

Priority Based QoS

With the simple stuff out of the way, let's move on to packet priority QoS features. Figure 3 shows the Global Configuration screen where you set the switch to handle packet priority via DSCP (Diffserv) or 802.1p. Both are protocols for communicating the priority of network packets, with the difference being that 802.1p is a Layer 2 protocol and DSCP is Layer 3.

QoS Global Configuration

Figure 3: QoS Global Configuration

The significance of the difference is that choosing 802.1p means that traffic will be prioritized on your LAN only. Once 802.1p packets hit a router, the 802.1p header will probably be dropped. This post, by a Microsoft QoS expert also mentions other reasons why 802.1p headers get lost. So, to me, 802.1p sounds like a not-so-good choice.

As a Layer 3 protocol, DSCP will survive going through routers (assuming they are DSCP-capable) and generally is considered more robust. DSCP also has the advantage of being visible to network sniffers like Wireshark, where 802.1p tags generally aren't. The reason why is mentioned in the Microsoft link above and in more detail here.

Actually, you probably won't be using either 802.1p or DSCP in a small LAN, since the sending and receiving devices actually have to set and act on the priorities communicated in the data. But if you do, the GS108T lets you map the eight 802.1p priorities (numbered 0 to 7) to four switch priority queues (Lowest, Low, Normal, Highest) if you select 802.1p based QoS.

If you select DSCP Based QoS, the DSCP Priority Mappings would be in effect. Figure 4 shows what those mapping look like. Aren't you glad that you have the simple Rate Limiting controls?

QoS Global Configuration

Figure 4: DSCP to Priority Mapping

Featured Sponsors

Win This!

TP-LINK Archer C9 & TL-PA4010KIT

You could win a TP-LINK Archer C9 AC1900 class router and AV500 Powerline Adapter kit

Learn How!

Top Performing Routers

AC3200
AC2350
AC1900
AC1750
AC1200

Top Performing NASes

NoRAID
RAID1
RAID5

Over In The Forums

Hi All, I've been following this guide to set up a secure vpn between two sites and have run into an issue. For the server side, I've installed open...
RT-AC87U 3.0.0.4.378_4608 Unofficial Beta Download: http://bit.ly/1HcAYC5 Better to keep this separate from the Official firmware posts. For ...
I know these builds are alphas, but I didn't know where to post this, so I'll post in here for you merlin. Last week I was having problems flashing m...
Do many people use these channels with on 5Ghz? Wondering what the advantage is, if any, to using them, opposed to 149,153,157,161?
Hey guys i just brought the Asus RT87U now im on my way home what firmware is the best Asus or Merlins firmware. ?? Im gonna use this router for gamin...

Don't Miss These

  • 1
  • 2
  • 3