Objectives of QoS
To ensure VoIP is an adequate backup for accepted PSTN telephony services, customers
must accept the aforementioned consistently aerial affection of articulation manual they receive
with basal blast services. Like added real-time applications, VoIP is acutely sensitive
to issues accompanying to bandwidth and delay. To ensure VoIP transmissions are intelligible
to the receiver, articulation packets cannot be dropped, badly delayed, or be accountable to
variations in adjournment (jitter). A acknowledged VoIP deployment charge accommodate an adequate level
of articulation affection by affair VoIP cartage requirements for issues accompanying to bandwidth,
latency, and jitter.
QoS refers to the adeptness of a arrangement to accommodate bigger account to called network
traffic over assorted basal technologies including Frame Relay, ATM, Ethernet and
802.1 networks, SONET, and IP-routed networks. VoIP guarantees high-quality voice
transmission alone if the signaling and audio approach packets accept antecedence over other
kinds of arrangement traffic.
In particular, QoS appearance accommodate bigger and added anticipated arrangement account by
implementing the afterward services:
■ Abutment affirmed bandwidth: Designing the arrangement so the all-important bandwidth
is consistently accessible to abutment articulation and abstracts traffic
■ Improve accident characteristics: Designing the Frame Relay network, for example, so
discard accommodation is not a agency for frames absolute voice, befitting articulation beneath the
committed advice amount (CIR)
■ Avoid and administer arrangement congestion: Ensuring the LAN and WAN infrastructure
can abutment the aggregate of abstracts cartage and articulation calls
■ Shape arrangement traffic: Using Cisco traffic-shaping accoutrement to ensure bland and consistent
delivery of frames to the WAN
■ Set cartage priorities beyond the network: Marking articulation cartage as antecedence and queuing
it first