What is QoS?
QoS stands for Quality of Service. This means that on the Internet as well as other networks, the delivery of information via packets can be measured and improved by analyzing transmission rates, error rates, and other characteristics and even to guaranteed the delivery in advance.
What is the Problem?
Assume an organization has a 1 Gb LAN and a 10 Mbps Internet connection. As long as computer send requests across the LAN internally, the transmission will not reach a bottleneck. But if the transmission has to hit the router to go to another network or to the Internet then there will be a problem. The Lan transmits data faster than the router can forward. The router has to hold the outgoing requests in queue and send each request as more bandwidth becomes available. The default setting for routers is first in-first out. So critical traffic could end up waiting in the queue behind less critical traffic.
Without QoS low priority traffic is treated like high priority traffic
How does QoS work?
When QoS is enabled, Windows marks outgoing packets with a code number, DSCP, Differentiated Services Code Point. Routers will examine the DSCP value and determine the priority value. In this way, the default queue configuration, first in-first out can be overriden when a DSCP value in a packet is higher than another.
QoS in Windows
Earlier versions of Windows addressed the QoS problem by prioritizing applications, IP addresses, and port numbers. This allowed them to match traffic to needs. High volume critical traffic on a server could be prioritized over a lesser critical server.
However, this was not granular enough. It became necessary to find ways to prioritize Web Traffic. One example of this problem would manefest itself when a server would handle a critical customer service database, and a non-critical customer forum on the same server. IP QoS would be of limited value in this case. Indeed, IT managers would need to find a way tohandle the traffic from each application differently, database-high, forum-low.
URL based QoS
URL priority can be defined in Windows 7. From the preceding example, it would be possible to assign the database application, with its URL a higher priority than the customer-forum.
URL based QoS allows IT professionals to prioritize Web traffic
How to Setup URL-based QoS
Click start – > Control Panel
Select Local Area Connection
QoS Packet Scheduler
Precedence Rules for URL based Policies
URL based policies are prioritized in a left-to-right reading order. So from the highest priority to the lowest priority, the URL fields are:
1. URL Scheme
2. URL Host
From the highest priority to the lowest, they are:
- Hostname
- IPv6 address
- IPv4 address
- wildcard
3. URL Port
4. URL Path
URL-Based QoS is an important step in managing web applications as they head out of the network. This gives the network administrator an addition tool by which to monitor traffic and reset priorities as needed.
