Zte ZXR10 5900E Product Description page 45

policies is also based upon the capability of the cache. It makes sure services of
different queues and different priorities can be scheduled according to certain
policies. When too many services are congested, and the queue length has
reached its threshold, all new arrivals will be discarded. This discarding mechanism
may cause TCP entire synchronization where messages of multiple TCP
connection queues will decrease at the same time, so that TCP connections start
congestion avoidance and slow start status to adjust traffic. What is worse, traffic
peak will pear at the same time making the network traffic fluctuate between
insufficient and saturation, which badly influence user's service experience.
To improve network quality, ZXR10 5900E adopts WRED to avoid congestion. ZXR10
5900E WRED can be aware of services, set policies for discarding messages of different
priorities, so that different messages can have different discarding policies.
3.2.12.2 Ethernet QoS
Because of the dramatic development of Metro Ethernet Service, there are more and
more Ethernet services in the network. ZXR10 5900E can process service scheduling
and congestion management as per the priority of VLAN frame. It can map IP message
priority or EXP priority of MPLS message to VLAN priority of Ethernet message to realize
integrated service scheduling. In QinQ mode, inner user VLAN priority can be mapped to
outer operator's VLAN priority automatically, or outer VLAN priority can be modified
according to user's service. This realizes integrated and manageable services from user
service to operator service tunnel.
Traditional Ethernet service is actually VLAN priority guarantee service based upon
Ethernet message. Normally there are 8 corresponding service types, and these services
can not be colored, so that, Ethernet service can not color services according to CIR/PIR
service marks to provide more differentiated service quality. In order to enhance Ethernet
service quality control and realize 5P3D model based upon VLAN service, ZXR10 5900E
classifies services according to 802.1P DE(Drop Eligible) which makes user services into
5 levels and 3 discarding priorities to color services.
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ZXR10 5900E Product Description
43