Member Avatar for Member #1095573

My questions are

What exactly is QoS ?

How does It work ?

Does It work on any network or like the RIP service It needs to be enabled on router/server side too ? / Is it client side ?
I have a D-Link 2730U ADSL modem , It has Enable DSCP/TC Mark & Enable 802.1P Mark & Scheduling Strategy (SP , WRR , CAR) what are all these ?

Whats values "Precedence" (also known as priority) can have ?

Is there any free PDF explaining about this ? (free because I can't buy anything on the internet due to restrictions -- I live in Iran)

I really hope this would also help others .

  • 3 Contributors
  • 2 Replies
  • 393 Views
  • 14 Hours Discussion Span
  • Latest Post Latest Post by Greg_z

Dani AI

Generated

Building on and : QoS isn’t a single switch — it’s a toolkit of functions used at the network edge and inside switches/routers: classification (identify flows), marking (set DSCP in IPv4/IPv6 or Traffic Class in IPv6), policing/shaping (limit or smooth bursts), queuing and scheduling (how marked packets are dequeued). The Differentiated Services (DSCP) field and service-class guidelines are the standards foundation for this behavior. (rfc-editor.org)

What the DSL‑2730U GUI items do (practical): “Enable DSCP/TC Mark” writes DSCP into the IP header (or Traffic Class for IPv6); “Enable 802.1P Mark” writes the 3‑bit PCP (0–7) into an 802.1Q tag for Layer‑2 CoS; the router’s Scheduling Strategy chooses how queues are served: SP = strict (priority) queuing, WRR = weighted round‑robin (shares bandwidth by weight), CAR = committed access rate (rate‑limit/police). For a home ADSL link, enable DSCP marking and configure a WAN queue that shapes upstream; prefer WRR with a small strict queue for voice rather than pure SP (to avoid starving lower queues). (manualslib.com)

Precedence and DSCP numbers: IP Precedence is 3 bits (0–7) and maps to Class Selector DSCPs (CS0..CS7 → decimal DSCP 0, 8, 16, …, 56). Expedited Forwarding (EF, DSCP 46) is the usual voice PHB; endpoints (softphones/PBX) can mark packets, but enforcement only happens where devices honor marks — and DSCP can be re‑marked or ignored further along the Internet, so edge shaping is the reliable way to protect real‑time traffic. (cisco.com)

Quick, practical checklist (fits the DSL‑2730U): measure real upstream speed, set the router’s upstream shaper to ~90–95% of measured upstream, enable DSCP marking, map EF to the voice queue, use WRR for the rest (weights for video/gaming/bulk). Read the DSL‑2730U QoS chapter and the DiffServ RFCs for exact values and examples: the DSL‑2730U manual, RFC 2474 (DS field) and RFC 4594 (service‑class guidelines) are good free reads. (ipaddresslocation.net)

References and further reading (free):

Recommended Answers

All 2 Replies

Member Avatar for CimmerianX

QOS is the term describing the prioritization of certain network services.

In a nutshell, an administrator can assign different levels of importance to network traffic. As an example, VOIP traffic should always be given highest priority while outbound http traffic could be relegated to a lower tier since no one cares if the cat video takes 10 seconds instead of 8 seconds to load.

Precedence is really defined by the equipment you use. But they all use a low-medium-high-highest style of assignment. Even prosumer routers can now be found with QOS settings. My home netgear even allows me to QOS my SIP traffic.

ANy gooogle search will show you dozens of pages explaining QOS. All for free.

Member Avatar for Greg_z

QOS can be maintained at either the hardware or software level. Most routers manufactured these days, will have QOS built into the firmware, but most will not allow end-user changes.

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.