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单选题
How many bits does EXP occupy in the MPLS label header？（）
A
8
B
4
C
3
D
1
E
2
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更多 “单选题How many bits does EXP occupy in the MPLS label header？（）A 8B 4C 3D 1E 2” 相关考题
考题
An ERX Edge Router is operating in an MPLS network using interface label space.What is used to make a forwarding decision?()
A. EXP bitsB. VPI / VCIC. shim headerD. SNAP header
考题
A router receives a packet from a neighbor with an MPLS shim header value of 0.What does the router do with this packet?()
A. It performs a label pop operation and an IP lookup.B. It performs a label swap operation and an IP lookup.C. It sends an error message toward the egress router.D. It sends an error message toward the ingress router.
考题
Which two QoS classification and marking statements are true？ （）A、 In a Frame Relay network， delay sensitive traffic is tagged with the discard eligible （DE） bit.B、 In an MPLS network， the three most significant bits of the DSCP or the IP precedence of the IP packet are copied into the MPLS EXP field.C、 In an MPLS network， the MPLS EXP bits are used to identify up to 16 CoS values.D、 The differentiated services code point （DSCP） field consists of the first three bits of the IP precedence field in the header of an IP packet.E、 The 802.1Q standard uses a three bit field referred to as the user priority bits （PRI） to mark packets as belonging to a specific CoS.
考题
Which two QoS classification and marking statements are true？（）A、 In a Frame Relay network， delay sensitive traffic is tagged with the discard eligible （DE） bit.B、 In an MPLS network， the three most significant bits of the DSCP or the IP precedence of the IP packet are copied into the MPLS EXP fieldC、 In an MPLS network， the MPLS EXP bits are used to identify up to 16 CoS values.D、 The differentiated services code point （DSCP） field consists of the first three bits of the IP precedence field in the header of an IP packet.E、 The 802.10 standard uses a three bitfield referred to as the user priority bits （PRI） to mark packets as belonging to a specific CoS.
考题
In the context of MPLS，what is the correct action to be performed when an aggregate label is received ？（）A、It adds the VPN label into the top label in the MPLS label stackB、It replaces the top label in the MPLS label stack with a VPN label and propagatesC、It replaces the bottom label in the MPLS label stack with a VPN label and propagatesD、It removes the top label in the MPLS label stack and does a Layer 3 lookup on underlying IP packetsE、None of above
考题
What is the action of "pop" in the context of MPLS switching？（）A、It removes the top label in the MPLS label stack.B、It adds a top label in MPLS label stack.C、It replaces the top label in the MPLS label stack with another value.D、It replaces the top label in the MPLS label stack with a set of labels.E、None of above.
考题
A router receives a packet from a neighbor with an MPLS shim header value of 0.What does the router do with this packet?（）A、It performs a label pop operation and an IP lookup.B、It performs a label swap operation and an IP lookup.C、It sends an error message toward the egress router.D、It sends an error message toward the ingress router.
考题
Which statement correctly describes the disabling of IP TTL propagation in an MPLS network？（）A、The TTL field from the IP packet is copied into the TTL field of the MPLS label header at the ingress edge LSRB、TTL propagation cannot be disabled in an MPLS domainC、TTL propagation is only disabled on the ingress edge LSRD、The TTL field of the MPLS label header is set to 255E、The TTL field of the IP packet is set to 0
考题
Where is the MPLS label imposed？（）A、after the Layer 3 header and before the Layer 2 payloadB、after the Layer 3 header and before the Layer 4 payloadC、after the Layer 2 header and before the Layer 1 payloadD、after the Layer 1 header and before the Layer 2 payloadE、after the Layer 2 header and before the Layer 3 payload
考题
In Any Transport over MPLS （AtoM） Control word is an optional 4-byte field used in the pseudowire packet.The control word carries generic and Layer 2 payload-specific information to emulate L2 packets correctly.In pseudowire packet， where is this Control Word inserted？（）A、Inserted between the MPLS label stack and the Layer 3 payloadB、Inserted between the MPLS label stack and the Layer 3 HeaderC、Inserted between the MPLS label stack and the Layer 2 payloadD、Inserted between the MPLS label stack and the Layer 2 header
考题
Which of the following is true about the MPLS header and its EXP field size？（）A、The MPLS header is 2 bytes，and the EXP field is 3 bits long.B、The MPLS header is 1 byte，and the EXP field is 3 bits long.C、The MPLS header is 4 bytes，and the EXP field is 3 bits long.D、The MPLS header is 3 bytes，and the EXP field is 3 bits long.
考题
An ERX Edge Router is operating in an MPLS network using interface label space.What is used to make a forwarding decision?（）A、EXP bitsB、VPI / VCIC、shim headerD、SNAP header
考题
单选题Which statement correctly describes the disabling of IP TTL propagation in an MPLS network？（）A
The TTL field from the IP packet is copied into the TTL field of the MPLS label header at the ingress edge LSRB
TTL propagation cannot be disabled in an MPLS domainC
TTL propagation is only disabled on the ingress edge LSRD
The TTL field of the MPLS label header is set to 255E
The TTL field of the IP packet is set to 0
考题
单选题MPLS Header长度为32bits，包括长度为20bits的标签，该标签用于报文转发；长度为3bits的EXP通常用来承载IP报文中的优先级，长度为1bit的栈底标志s，用来表明是否是最后一个标签（）A
作用类似IP头部的TTL，用来防止报文环路B
主要是用于标签管理时的控制C
用于标签分发时对上游设备的控制D
对于LSR进行限制
考题
单选题MPLS Header长度为32bits，包括长度为20bits的标签，该标签用于报文转发；长度为3bits的EXP通常用来承载IP报文中的优先级；长度为1bit的栈底标志S用来表明是否是最后一个标签（MPLS标签可以多层嵌套）；长度为8bits的TTL，对TTL的描述正确的是（）。A
作用类似IP头部的TTL，用来防止报文环路等B
主要是用于标签管理时的控制C
用于标签分发时对上游设备的控制D
对于LSR这块进行限制
考题
多选题Which three statements about classification marking of traffic at Layer 2 are true？ （）Aa Frame Relay header includes a 1-bit discard eligible （DE） bit to provide the class of service （CoS）Ban ATM header includes a 1-bit DE field to provide the CoSCan MPLS EXP field is inserted in the Layer 3 IP precedence field to identify the CoSDthe CoS field only exists inside Ethernet frames when 802.1Q or Inter-Switch Link （ISL） trunking is usedEin the IEEE 802.1p standard， three bits are used to identify the user priority bits for the CoSFin the IEEE 802.1q standard， six bits are used to identify the user priority bits for the CoS
考题
单选题Which of the following is true about the MPLS header and its EXP field size？（）A
The MPLS header is 2 bytes，and the EXP field is 3 bits long.B
The MPLS header is 1 byte，and the EXP field is 3 bits long.C
The MPLS header is 4 bytes，and the EXP field is 3 bits long.D
The MPLS header is 3 bytes，and the EXP field is 3 bits long.
考题
多选题Which two QoS classification and marking statements are true？ （）AIn a Frame Relay network， delay sensitive traffic is tagged with the discard eligible （DE） bit.BIn an MPLS network， the three most significant bits of the DSCP or the IP precedence of the IP packet are copied into the MPLS EXP field.CIn an MPLS network， the MPLS EXP bits are used to identify up to 16 CoS values.DThe differentiated services code point （DSCP） field consists of the first three bits of the IP precedence field in the header of an IP packet.EThe 802.1Q standard uses a three bit field referred to as the user priority bits （PRI） to mark packets as belonging to a specific CoS.
考题
单选题In a frame ，the MPLS label is imposed（）.A
After the Layer3 header and before Layer2 headerB
After the Layer2 header and before Layer3 headerC
Within the Layer 3 headerD
Before the layer 2 header
考题
单选题Where is the MPLS label imposed？（）A
after the Layer 3 header and before the Layer 2 payloadB
after the Layer 3 header and before the Layer 4 payloadC
after the Layer 2 header and before the Layer 1 payloadD
after the Layer 1 header and before the Layer 2 payloadE
after the Layer 2 header and before the Layer 3 payload
考题
单选题An ERX Edge Router is operating in an MPLS network using interface label space.What is used to make a forwarding decision?（）A
EXP bitsB
VPI / VCIC
shim headerD
SNAP header
考题
单选题In the context of MPLS，what is the correct action to be performed when an aggregate label is received ？（）A
It adds the VPN label into the top label in the MPLS label stackB
It replaces the top label in the MPLS label stack with a VPN label and propagatesC
It replaces the bottom label in the MPLS label stack with a VPN label and propagatesD
It removes the top label in the MPLS label stack and does a Layer 3 lookup on underlying IP packetsE
None of above
考题
单选题A router receives a packet from a neighbor with an MPLS shim header value of 0.What does the router do with this packet?（）A
It performs a label pop operation and an IP lookup.B
It performs a label swap operation and an IP lookup.C
It sends an error message toward the egress router.D
It sends an error message toward the ingress router.
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