Chapter 1 – Implement VLAN based solution, given a network design and a set of requirements
QUESTION NO: 46
Which of the following technologies would an Internet Service Provider use to support overlapping customer VLAN ID’s over transparent LAN services?
A. 802.1q tunneling
B. ATM
C. SDH
D. IP Over Optical Networking
E. ISL
Answer: A
Explanation:
Understanding How 802.1Q Tunneling Works: The 802.1Q tunneling feature supports secure virtual private networks (VPNs). 802.1Q tunneling enables service providers to keep traffic from different customers segregated in the service provider infrastructure while significantly reducing the number of VLANs required to support the VPNs. 802.1Q tunneling allows multiple customer VLANs to be carried by a single VLAN on the Catalyst 6000 family switch without losing their unique VLAN IDs. When you configure 802.1Q tunneling on the Catalyst 6000 family switch, traffic to be tunneled comes into the switch from an 802.1Q trunk port on a neighboring device and enters the switch through a port configured to support 802.1Q tunneling (a tunnel port). When the tunnel port receives traffic from an 802.1Q trunk port, it does not strip the 802.1Q tags from the frame header but, instead, leaves the 802.1Q tags intact and puts all the received 802.1Q traffic into the VLAN assigned to the tunnel port. The VLAN assigned to the tunnel port then carries the tunneled customer traffic to the other neighboring devices participating in the tunnel port VLAN. When the tunneled traffic is received by an 802.1Q trunk port on a neighboring device, the 802.1Q tag is stripped and the traffic is removed from the tunnel.
QUESTION NO: 47
If you were to configure an ISL Ethernet trunk between two Cisco switches, named R1 and R2, what would you have to include at the end of the link for the trunk to operate correctly? (Select two)
A. An identical VTP mode.
B. An identical speed/duplex.
C. An identical trunk negotiation parameter.
D. An identical trunk encapsulation parameter.
Answer: B,D
Explanation:
In order for a trunk to be operational, the speed and duplex settings must match at each end of the trunk, and both switches must use the same trunking encapsulation (802.1Q or ISL).
QUESTION NO: 48
You are the network administrator at Company and switch R1 is configured as shown below:
Interface gigethernet 0/1 Switchport mode trunk
Switchport trunk encapsulation dot1q
Switchport trunk native vlan 5
If untagged frames are arriving on interface gigethernet 0/1 of R1, which of the following statement are correct?
A. Untagged frames are automatically assumed to be in VLAN 5.
B. Untagged frames are defaulted to VLAN 1 traffic.
C. Untagged frames are dropped because all packets are tagged when dot1q trunked.
D. Untagged frames are determined on the other switch
E. Untagged frames are not supported on 802.1Q trunks.
Answer: A
Explanation:
Each physical port has a parameter called PVID. Every 802.1Q port is assigned a PVID value that is of its native VLAN ID (default is VLAN 1). All untagged frames are assigned to the LAN specified in the PVID parameter. When a tagged frame is received by a port, the tag is respected. If the frame is untagged, the value contained in the PVID is considered as a tag. All untagged frames will be assigned to the native VLAN. The native VLAN is 1 by default, but in this case the native VLAN is configured as VLAN 5 so choice A is correct.
QUESTION NO: 49
If you were to set up a VLAN trunk over a Fast Ethernet link on switch R1, which trunk mode would you set the local port to on R1 if you wanted it to respond to requests from its link partner (R2) and become a trunk?
A. Auto
B. Negotiate
C. Designate
D. No negotiate
Answer: A
Explanation:
Only ports in desirable and auto mode will negotiate a channel (either desirable-auto or desirable?desirable). Ports in on mode will only form a functional channel with other ports in on mode (they will not negotiate a channel with ports in desirable or auto mode). Reference: Cisco, Troubleshooting Tips
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