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CCNP SPVI > 9-4 - Use 6PE to Deploy IPv6 Connectivity over MPLS Environment > Flashcards

9-4 - Use 6PE to Deploy IPv6 Connectivity over MPLS Environment Flashcards

1
Q

Describe 6PE.

A

6PE enables IPv6 islands to communicate with each other over an MPLS IPv4 core network by using MPLS label-switched paths (LSPs).

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2
Q

T/F: The method (6PE) relies on BGP extensions in the IPv4 network PE routers (Cisco 6PE routers) to exchange IPv6 reachability information and an MPLS label for each IPv6 address prefix that is announced. Cisco 6PE routers are dual stack (IPv4 and IPv6).

A

True

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3
Q

T/F: With Cisco 6PE, IPv6 forwarding in the core of the MPLS network occurs by label switching, which eliminates the need for either IPv6-over-IPv4 tunnels or an extra Layer 2 encapsulation.

A

True

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4
Q

T/F: Each involved PE router does not need to support dual-stack to support 6PE.

A

False. You must upgrade each PE router that must support IPv6 connectivity to dual stack (so that it becomes a Cisco 6PE router) and configure it to run MPLS on the interfaces that connect to the core.

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5
Q

T/F: The Cisco 6PE routers encapsulate IPv6 traffic by using two levels of MPLS labels. The top label is distributed by an LDP or Tag Distribution Protocol (TDP) that devices in the core use to carry the packet to the egress Cisco 6PE router by using IPv4 routing information. The second or bottom label associates with the IPv6 prefix of the destination through MP-BGPv4.

A

True

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6
Q

Multiprotocol extensions for BGPv4 are characterized as follows:

A
  • BGPv4 is the primary mechanism to exchange IPv6 reachability information for Cisco 6PE and IPv6 VPN Provider Edge (6VPE).
  • Label binding information piggybacks with the prefix advertisement in a Network Layer Reachability Information (NLRI) attribute.
  • BGP protocol extensions, which carry routing information about other protocols, include multicast, MPLS, IPv6, VPN-IPv4, labeled IPv6 unicast (Cisco 6PE), and Cisco 6VPE.
  • The exchange of multiprotocol NLRI must be negotiated at the session setup. The exchange uses BGP capability advertisement negotiation procedures.
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7
Q

This process describes how the reachability establishes between Cisco 6PEs:

A
  1. IGPv4 advertises the reachability of PE routers. The Cisco 6PE routers exchange IPv6 routing information through MP-BGP. The Cisco 6PE routers peer together through MP-BGPv4 to exchange IPv6 reachability with the MPLS cloud and to perform IPv6 forwarding. IGP advertises the reachability of the BGP next-hop address, which is 192.0.2.133.
  2. LDPv4 binds labels to create LSPs.
  3. The 6PE2 router sends MP-BGP advertisements to the ingress PE router, 6PE1.
  4. The BGP next hop for the destination IPv6 prefix is set to an IPv4-compatible address, which is built from the 6PE2 router. The MPLS label binds to the IPv4- or IPv6-mapped address, which is formed from the IPv4 address of 6PE2 (192.0.2.133). Thus, other Cisco 6PE routers (which are part of the mesh edges around the MPLS core) see 6PE2 ::FFFF:192.0.2.133 as the next-hop IPv6 address when a packet must forward to the 2001:DB8:4:: network.
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8
Q

Follow these steps to deploy Cisco 6PE:

A
  • Configure Cisco 6PE routers as dual-stack routers. The CE-facing interfaces have IPv6 addresses. The core-facing interfaces have IPv4 addresses.
  • Configure Cisco 6PE routers to be part of the IPv4 network and configure MPLS. This configuration does not display in the example. The OSPFv3 process 10 on each PE router is enabled to provide CE-PE IPv6 routing.
  • Configure MP-IBGP. The MP-IBGP session originates from the Loopback 0 IPv4 address of each PE router.
  • Enable MP-BGP label exchange for IPv6 networks. In Cisco IOS XR devices, you must enable address-family ipv6 labeled-unicast in the BGP neighbor configuration mode. You must configure label allocation policy. In this example, 6PE1 will allocate labels to all IPv6 routes as a result of the allocate-label all command. In Cisco IOS and Cisco IOS XE devices, you must enable lab
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9
Q

IOS-XR Command:
show bgp ipv6 labeled-unicast
show bgp ipv6 labeled-unicast <ipv6></ipv6>

A
  • Show IPv6 labelled routes information in BGP
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10
Q

T/F: You can monitor the label-swapping operation by using the traceroute utility

A

True

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11
Q

What is true about using 6PE?

A. Cisco 6PE enables IPv6 islands to communicate with each other over an MPLS IPv4 core network by using OSPF.
B. Each PE router that must support IPv6 connectivity must be upgraded to dual stack.
C. Cisco 6PE uses MPLS to maximize changes in the ISP core network.
D. Cisco 6PE routers are dual stack (MPLS and OSPF).

A

B

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CCNP SPVI (59 decks)

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