12 - Introducing Virtualisation Protocols and Techniques

Question 1

___ refers to the creation of independent logical traffic paths over a shared physical infrastructure

Answer 1

path isolation

Question 2

What is a hypervisor?

Answer 2

• Thin OS between hardware and virtual machine
• allocates resources to virtual machines
• Manages VMs (create, modify, destroy, move)

Question 3

The virtualisation of the interconnection between devices is called…

Answer 3

data path virtualisation

Question 4

___ combines the used of VRF instances with either 802.1q trunking for hop-by-hop path isolation or GRE/multipoint GRE for multihop path isolation

Answer 4

VRF-lite

Question 5

__ can also be used to extend VRFs across an IP infrastructure, and would be the best choice for large scale enterprises that require more than 32 virtual networks per device, or require traffic engineering and optimal path selection with Fast Reroute capabilities along with the ability to provide extremely scalable full mesh connectivity.

Answer 5

MPLS

Question 6

Within each networking device, there are two planes to virtualise. What are these?

Answer 6

• Control plane – all the protocols, databases and tables necessary to make forwarding decisions and maintain a functional network toplogy free of loops or unintended black holes
• Forwarding plane – all the processes and tables used to forward traffic

Question 7

A VRF consists of…

Answer 7

• IP routing table
• A derived forwarding table
• Set of interfaces that use the forwarding table
• Set of rules and routing protocols that determine what goes into the forwarding table

Question 8

What are some advantages of VRF-lite technology?

Answer 8

• Allows for routing and forwarding separation
• Simplifies the management and troubleshooting of traffic belonging to specific VRF
• Enables support for alternate default routes

Question 9

How do you apply a VRF to an interface?

Answer 9

ISP(config)# interface Ethernet 0/1
ISP(config-if)# ip vrf forwarding CUST-A
% Interface Ethernet0/1 IPv4 disabled and address(es) removed due to enabling VRF CUST-A
ISP(config-if)# ip address 172.16.2.18 255.255.255.240

Question 10

Why does applying a VRF remove the addressing?

Answer 10

Because the interface is being moved from global routing table to VRF routing table

Question 11

What commands verifies a VRF?

Answer 11

show ip vrf , show ip vrf interfaces

Question 12

Generic routing encapsulation – a tunnelling protocol which provides a secure path for transporting packets over a public network by encapsulating packets inside a ___ protocol

Answer 12

transport

Question 13

What are the main characteristics of GRE?

Answer 13

• One of many tunnelling protocols
• IP protocol 47 defines GRE packets
• Allows routing information to pass between connected networks
• No encryption used

Question 14

GRE adds a __ byte IP header and a _ byte GRE header, hiding existing packet headers

Answer 14

20, 4

Question 15

A GRE header contains a ___ field and ___ field to identify the L3 protocol being transported. It may contain a tunnel checksum, tunnel key and tunnel sequence

Answer 15

flag, protocol type

Question 16

GRE does not __ traffic or use any strong security measures to protect traffic

Answer 16

encrypt

Question 17

GRE can be used along with ___ to provide data source authentication and data confidentiality, and data integrity

Answer 17

IPSec (IP security)

Question 18

GRE over IPsec tunnels are typically configured in a___ topology over an untrusted WAN in order to minimise the number of tunnels that each router must maintain

Answer 18

hub and spoke

Question 19

A tunnel interface supports a header for each of the following…

Answer 19

• A passenger protocol or encapsulated protocol such as ipv4 or ipv6, this protocol is the one being encapsulated
• A carrier or encapsulation protocol (GRE, in this case)
• A transport deliver protocol, such as IP, which is the protocol that carries the encapsulated protocol

Question 20

You may have to adjust the __ on GRE tunnels by using the __ interface configuration command. This must match both sides.

Answer 20

MTU, ip mtu

Question 21

How do you configure a GRE tunnel?

Answer 21

Create a tunnel interface.
• Router(config)# interface tunnel tunnel-id
Configure the GRE tunnel mode. This mode is a default tunnel mode so it is not necessary to configure it.
• Router(config-if)# tunnel mode gre ip
Configure an IP address for the tunnel interface.
• Router(config-if)# ip address ip-address mask
Specify the tunnel source IP address.
• Router(config-if)# tunnel source ip-address
Specify the tunnel destination IP address.
• Router(config-if)# tunnel destination ip-address

Question 22

How do you verify if tunnel interface is up or down?

Answer 22

show ip inter brief tunnel tunnel-id

Question 23

How do you show the state of GRE tunnel?

Answer 23

show interface tunnel tunnel-id