The access layer is the initial point at which traffic enters the network. Traffic is marked (orremarked) at Layers 2 and 3 by the access switch as it enters the network, or is trusted that it isentering the network with the appropriate tag
No traffic marking occurs at the core layer. Layer 2/3 QoS tags are trusted from distributionlayer switches and used to prioritize and queue the traffic as it traverses the core
Traffic inbound from the access layer to the distribution layer can be trusted or reset dependingupon the ability of the access layer switches. Priority access into the core is provided based onLayer 3 QoS tags
IP precedence, DSCP, QoS group, IP address, and ingress interface are Layer 2 characteristics that are set by the access layer as it passes traffic to the distribution layer. Thedistribution layer, once it has made a switching decision to the core layer, strips these off
MAC address, Multiprotocol Label Switching (MPLS); the ATM cell loss priority (CLP) bit, theFrame Relay discard eligible (DE) bit, and ingress interface are established by the voicesubmodule (distribution layer) as traffic passes to the core layer
The distribution layer inspects a frame to see if it has exceeded a predefined rate of trafficwithin a certain time frame, which is typically a fixed number internal to the switch. If a frame isdetermined to be in excess of the predefined rate limit, the CoS value can be marked up in a waythat results in the packet being dropped
第1题:
You work as network consultant. Your customer, TestKing Inc, has a class C network license. TestKing wants you to subnet the network to provide a separate subnet for each of its 5 departments. Each subnet must support at least 24 hosts.Which network mask should you use?()
A.255.255.255.192
B.255.255.255.224
C.255.255.255.240
D.255.255.255.248
E.255.255.255.252
F.255.255.255.254
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第3题:
(英译汉)There is no separation for you between work and home.
Even when at home, your work is the top priority.
You are totally committed and driven to work, and your happiness is found in your work.
Work always seems to take precedence over family and leisure time.
You have no social life other than work-related events.
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第8题:
You work as a network administrator in your company. Communication inside the company is ensured by network environments, such as GET VPN, Dynamic Multipoint VPN and Ethernet.Which PIN architecture is applicable in those environments?()
A.Campus
B.Teleworker
C.Branch
D.Data center
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