TS INE V1:1.1

USEFULL COMMANDS:

sh cdp neighbor
sh int status
sh vlan br
ping
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PROBLEMS FACED:
1) In the output of sh cdp ne cmd some devices are missing based on L2 diag.
- Because, directly connected interfaces were shutdown.
- based on the L2-diag we know the directly connected devices.
- After using no shutdown on  connected interfaces  then only directly connected devices appear in sh cdp neigh cmd.
2) un successful of ping cmd
- some times interfaces were shutdown
- some times switches between source & destination have

• required vlans are not created
• in between source to destination every switch must contain corresponding vlan
• check the required vlans & corresponding interfaces by using sh vlan br
• then create vlans according l3-diag
• create vlan around switches from diagrom
• Some interfaces of switches are connected routers but not showed in L3-dag
• easily identified by a straight line connected to 2 or more devices
• some times simply a straight line
• That inter faces are connected to switches
• 
  

Label Switching Functions

• In label switching, analysis of the layer 3 header is done only once.
• After this analysis, add a fixed length, unstructured value called a label.
• Many different header add to the same label (those headers are have same next hop)
• i.e. a label represents a forwarding equivalence class
• Means a set of packets which are different but they are indistinguishably by the forwarding function.
• The initial choice of label may not depend upon the content of layer 3 packet header
• Ex: Forwarding decisions at subsequent hops can also be based on routing policies.
• The packet header need not be reanalysis  during packet transit through the network.
• Because the label is fixed length and unstructured.
• So the MPLS forwarding table lookup process is straight forward & fast