Quality of Service (QoS) in networking is the use of mechanisms or technologies that work on a network to control traffic and ensure the performance of critical applications with limited network capacity.
Network QoS Architectures
QoS architectures:
- Best-effort
- IntServ
- DiffServ
- MPLS QoS
Best-effort
Best-effort is the simplest QoS architecture and offers no guarantee.
Integrated Services
Integrated Services (IntServ) or hard QoS model needs a request for resource reservation by applications to the network, and does not escalate well.
It is defined as fine-grained, in contrast to DiffServ coarse-grained.
It makes use of the protocol Resource Reservation Protocol (RSVP) on the OSI model layer 4 / transport. You can read this post about RVSP.
DiffServ
Differentiated Service (DiffServ) or soft QoS model is based on statistical preferences per traffic class. It is more scalable than integrated.
It uses the DiffServ Code Point (DSCP) field within the IPv4 header on the OSI model layer 3. You can read this post about IPV4 and its header structure.
MPLS QoS
MPLS networks support QoS natively by using packet labeling and classification.
You can read this post about MPLS.
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External References
- QoS Architectures
- Cisco; “QoS architecture models“; Cisco
- IntServ
- Wikipedia community; “Integrated Service“; Wikipedia
- DiffServ
- Wikipedia community; “Differentiated Service“; Wikipedia