Specifications

Terms and Definitions
May 09, 2011 Page 36 of 38
s-series(rw)->set policy rule admin-profile vlantag 12 mask 12 port-string
ge.1.10-13 admin-pid 1
s-series(rw)->set policy rule 1 vlantag 12 mask 12 vlan 12 cos 9
s-series(rw)->set cos port-resource irl 2.1 0 unit mbps rate 1
s-series(rw)->set cos reference irl 2.1 9 rate-limit 0
s-series(rw)->set cos 9 priority 5 tos-value 184.0 txq-reference 8 irl-reference 1
s-series(rw)->set policy profile 2 name H323CallSetup cos 5 tci-overwrite enable
s-series(rw)->set policy rule admin-profile port ge.1.10 mask 16 port-string
ge.1.10 admin-pid 2
s-series(rw)->set policy rule 1 tcpdestportIP 1720:10.0.0.1 cos 10 port-string
ge.1.10
s-series(rw)->set cos port-resource irl 3.1 2 unit pps rate 5
s-series(rw)->set cos reference irl 3.1 10 rate-limit 1
s-series(rw)->set cos 10 priority 5 tos-value 184.0 txq-reference 8 irl-reference
2
s-series(rw)->set cos state enable
Terms and Definitions
Table 3liststermsanddefinitionsusedinthisQualityofServiceconfigurationdiscussion.
Table 3 Quality of Service Configuration Terms and Definitions
Term Definition
Class of Service
(CoS)
The grouping of priority and forwarding behaviors that collectively determine packet
bandwidth behavior as it transits the link, including: 802.1p, IP ToS rewrite, priority
Transmit Queue (TxQ), Inbound and/or outbound Rate Limiter (IRL) and outbound
rate shaper.
DSCP Differentiated Services Code Point. The lower 6 bits of the ToS field defined by RFC
2474.
Flows In a QoS context, a sequence of IP packets that share a common class of service
and forwarding treatment as they transit the interface.
Forwarding
Treatment
Queue behavior during the packet egress stage (strict priority, weighted fair, hybrid).
Jitter The change in a flow’s packet spacing on the link due to the bursty and congestive
nature of the IP network. This irregular spacing - jitter - can severely degrade the
quality of voice calls or multimedia presentations.
Port Group The grouping of ports based upon the same CoS features and port type.
Port Type The differentiation of ports based upon TxQ, IRL, ORL, and flood control resource
capabilities.
Priority The preference of one packet (classification) or queue (packet forwarding) over
another.
Quality of Service
(QoS)
A bandwidth management mechanism able to preferentially treat packets based
upon packet classification and forwarding treatment.
Rate Limiting The bounding of bandwidth used by a QoS packet flow such that excess packets are
dropped/clipped.