ccnp sw ch 11

  1. Which of the following arrangements can be considered interVLAN routing?

  2. How many interfaces are needed in a "router on a stick" setup for inter-vlan routing among 4 VLANs?

    a. 1
    b. 2
    c. 4
    d. Can't be determined
  3. Which of the following cmds configures a sw port for layer 2 operations?

  4. Which of the following cmds configures a sw port for layer 3 operations?

  5. Which one of the following interfaces is an SVI?

  6. What information must be learned before CEF can forward packets?

  7. Which of the following best describes an adjacency?

  8. Assume that CEF is active on a switch. What happens to a packet that arrives needing fragmentation?

  9. Suppose that a host sends a packet to a destination IP address and that the CEF-based switch does not yet have a valid MAC address for the destination. How is the ARP entry (MAC address) of the next-hop destination in the FIB obtained?

  10. During a packet rewrite, what happens to the source MAC address?

  11. What cmd can you use to view the CEF FIB table contents?

  12. Which one of the following answers represents config cmds needed to implement DHCP relay function?

    a. int vlan 5
    ip add
    ip helper-add

    b. int vlan 5
    ip add
    ip dhcp-relay

    c. ip dhcp pool staff

    d. hostname Switch
    ip helper-address
  13. Describe inter-vlan routing.
    where packets between vlans are sent.  This must be accomplished by a L3 device.

    multi-interfaces from sw to the router

    single int from sw to router (rtr on a stick) using trunking protocol

    multilayer sw
  14. Define a SVI  (Switched Virtual Interface)

    What is the common name for a SVI?
    where a logical interface is made and assigned an IP address that represents the whole VLAN.

    The VLAN id
  15. what cmd puts a L3 port into L2 mode?
    • G  int fa 0/1
    • I  switchport
  16. what cmd puts a L2 port into L3 mode?

    what cmd lets you see the status of the switchport?
    • G  int fa 0/1
    • I   no switchport
    • I   ip add
    • I   no shut

    • sh int fa 0/1 switchport
    • look for line -  Switchport:  (enabled or disabled)
    • switchport enabled = L2
  17. For CEF, describe the two paths a packet can take, and what functions are in each path.
    Layer 3 engine - routing table and ARP table - works like a router,

    Layer 3 forwarding engine - FIB table and Adjacency table.  Adjacency table drops into the rewrite engine.

    • FIB - Forwarding Information Base -
    • reformatted routing table, longest prefix first
    • next-hop address for each entry
    • host route (route to directly connected vlans)

    FIB works with Routing table and ARP table on L3 Engine to stay updated.
  18. describe CEF punt
    Where any number of things are missing and the L3 forwarding engine can't process the packet.

    • no entry in FIB
    • table is full
    • IP TTL is expired
    • MTU is exceeded
    • ICMP redirect
    • bad encap type
    • tunneled packets
    • access-list with logging
    • NAT
  19. Describe the function of the adjacency table.
    part of FIB that holds L2 info for every L3 next hop entry. 

    MAC addresses

    Adjacency table is built from the ARP table. If ARP entry is aged out, then the next packet is punted to the L3 engine to generate a ARP request.  This is called CEF glean
  20. After FIB table processing, the packet gets sent to the re-write engine.  What changes are made to the packet?
    • L2 dest address - changed to next hop MAC address
    • L2 source add - changed to outbound L3 sw int MAC adress
    • L3 IP TTL
    • L3 IP checksum
    • L2 frame checksum
  21. What cmd verifies configuration of L3 switchport?
    sh int fa 0/16 switchport

    • note:
    • switchport: disabled       = L3 port
    • switchport: enabled       = L2 port
  22. what cmd shows you the configuration of an SVI?
    sh int vlan <vlan-id>
  23. cmd that displays list of configured VLANs?
    sh vlan

    sh vlan brief
  24. cmd that shows ip related info about a switch int?
    sh ip int vlan 101
  25. display a summary list of interfaces routing IP traffic?
    sh ip int bri
  26. display contents of FIB

    display FIB details for a specific interfact
    sh ip cef

    sh ip cef vlan 101 [detail]
  27. What are the 4 steps for DHCP process?
    dhcp discover message broadcast

    server sends dhcp offer message

    client sends dhcp request

    dhcp server with dhcp ack message
  28. detail DHCP cmds inside a sw or router.

    how do you verify addresses leases?
    • G  ip dhcp excluded-address
    • G  ip dhcp pool <pool-name>
    • d  network
    • d  default-router
    • d  lease {infinite | {days, hours, minutes}}

    sh ip dhcp binding
  29. what cmd relays dhcp broadcasts to the correct subnet?

    ip helper-address

    • G  int vlan5
    • I   ip address
    • I   ip helper-address
    • I   exit
  30. cmd for viewing FIB info for an IP prefix?
    sh ip cef [longer-prefixes] [detail]
  31. view counters for packets not switched by CEF?
    sh cef not-cef-switched
  32. view FIB adjacency table
    show adjacency [int fa 0/1 | vlan vlan5]  [summary | detail]
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ccnp sw ch 11
ch 11