3-6 - Implementing Extranet and Shared Services in Layer 3 MPLS VPNs

Question 1

What is an extranet?

Answer 1

An extranet is a private network that connects two or more businesses.

Question 2

What is a shared services VPN?

Answer 2

A shared services VPN is an MPLS L3VPN that imports route targets from other VRFs, enabling resources from two or more L3VPNs to communicate with one another.

Question 3

T/F: RDs can identify participation in more than one VPN.

Answer 3

False. RDs cannot identify participation in more than one VPN.

Question 4

Describe route targets (RTs).

Answer 4

• Route targets (RTs) support the capability to identify a site that participates in more than one VPN
• You can import and export multiple different route-targets
• BGP extended communities are used to implement RTs, where the higher-order 16 bits of the 64-bit extended community encodes the value that corresponds to the VPM membership of the particular site.

Question 5

T/F: The selective import feature allows you to choose the routes to import into a VRF that are based on criteria other than the RT of the VRF

Answer 5

True

Question 6

T/F: The selective export feature allows you to attach specific RTs to a subset of routes that export from a VRF (by default, the same RTs attach to all exported routes)

Answer 6

True

Question 7

T/F: MPLS VPN RTs exist on the customer route as soon as the customer announces it upstream to the PE router.

Answer 7

False. MPLS VPN RTs attach to a customer route at the moment that the PE router converts it from an IPv4 route to a VPNv4 route.

Question 8

IOS/IOS-XE Command:
route-target [import | export | both] [route-target-ext-community value]

Answer 8

in VRF subconfig mode, this configures an RT to be used for import, export, or both

Question 9

You can specify RTs in one of these two formats.

Answer 9

• 16-bit AS number followed by a 32-bit decimal number (ASN:nn)
• 32-bit IP address followed by a 16-bit decimal number (A.B.C.D:nn)

Question 10

IOS-XR Command:
[export | import] route-target

Answer 10

in VRF/address-family subconfig mode, this configures an RT to be used for import or export

Question 11

IOS-XR Command:
[import | export] route-policy [route-policy name]

Answer 11

apply a route-policy that controls the import or export of routes into the VRF based on other criteria/conditions defined in the route-policy

Question 12

T/F: You can use the “additive” keyword to add a route target to other export route targets

Answer 12

True

Question 13

Name some use-cases for shared service VPNs.

Answer 13

• Extranet VPN
• Network Management VPN
• Internet Access VPN

Question 14

What is true about selective route propagation and filtering?

A. The RDs that attach to the route are called export RDs.
B. RDs can identify a site that participates in more than one VPN.
C. A single prefix associates to only one export route target.
D. A virtual routing table in a PE router can have multiple configured import RTs.

Answer 14

D