【Answer】1.B 2.ABCDE 3.AC 4.C 5.A
【Winner】Vien，SMILEIQ，Wassim，IndianKid，nagu
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Hello, everyone!
Join the Community Learning week Network Routing&Switching MPLS topic!
Network class learning time of this phase: April 19th - April 24th.
Answer time of this class: April 23th, 2 AM - April 24th, 10 AM (UTC+0)
Class topic
Post 1. MPLS Basics concept
Label Switch Router (LSR) is a router that supports MPLS. LSRs can learn MPLS labels and exchange MPLS-labeled packets with each other at the data link layer. Forwarding Equivalence Class (FEC) is a data flow that is processed in the same mode during forwarding... More
Post 2. LDP Peer Relationship Establishment
LDP uses Hello packets to discover peers on a link. Hello packets are sent in multicast mode. The source IP address is the interface IP address, and the destination IP address is 224.0.0.2... More
Post 3. PHP Mechanism
Penultimate Hop Popping (PHP) is a basic mechanism of MPLS. Once the PHP mechanism is used, the router assigns special label 3 for the local route. When a label switching router (LSR) receives a labeled packet and searches the LFIB table, if the egress label value is 3, the LSR needs to pop out the top label from the packet... More
Post 4. MPLS Label Distribution, Advertisement, and Management
The label distribution mode is the prerequisite for a label switching router (LSR) to map or allocate a label to an FEC. An LSR can assign a label to an FEC without the need to wait for the Label Mapping message from the downstream node in the independent control mode... More
Post 5. MPLS VPN Overview
The MPLS VPN backbone network is constructed by a carrier. The network provides VPN services for customers so that the routes and data of different customers can be transmitted through this public network without interference. Routes and data between customers are completely isolated even if they are carried over the same carrier network... More
Class Questions
After attending this class, please answer the following questions and comment with the answers below this post.
1. The label stack is placed after the network layer header.
A.True
B.False
2. (Multiple-Choices Question)Which of the following are LDP peer state machines?
A. Non-Existent
B. Innitialized
C. Open-Recived
D. Open-sent
E. Operational
3. (Multiple-Choices Question)Which of the following are the lable types involved in the PHP mechanism?
A. Implicit null label with label value 3
B. Implicit null label with label value 0
C. Explicit null label with label value 0
D. Explicit null label with label value 3
4. What is the length of an RD? (bit)
A. 16
B. 32
C. 64
D. 128
5. If the LSR works in liberal retention mode, it retains all label mappings sent by all its peers into the label database. This increases the device burden, but enables LSPs to be quickly switched if the network topology changes. By default, Huawei devices work in the liberal retention mode.
A. True
B. False
Hope you get good grades, come and enjoy this learning party! 
Click to learn: >>> previous class – Access Network topic
