CCNP Multicast and IPv6 Flashcards

What is the purpose of 6to4 tunneling in IPv6 transition?

Answer: Encapsulates IPv6 packets inside IPv4 packets to traverse IPv4-only networks using the 2002::/16 prefix

6to4 automatically embeds the IPv4 address into a 2002::/16 IPv6 prefix, allowing isolated IPv6 sites to communicate over an IPv4 backbone without manual tunnel configuration.

What is ISATAP (Intra-Site Automatic Tunnel Addressing Protocol) used for?

Answer: Provides IPv6 connectivity between dual-stack nodes within an IPv4 site by using IPv4 addresses as the interface identifier

ISATAP enables IPv6 communication within a site by embedding the IPv4 address into the interface ID (::0:5EFE:) to create an IPv6-over-IPv4 tunnel automatically.

What is MLDv2 (Multicast Listener Discovery version 2) used for in IPv6 networks?

Answer: Allows IPv6 hosts to report multicast group membership including source-specific requests to their local router

MLDv2 is the IPv6 equivalent of IGMPv3 and allows hosts to signal both group membership and specific source preferences to their local router for SSM support.

What is the key difference between PIM Dense Mode (PIM-DM) and PIM Sparse Mode (PIM-SM)?

Answer: PIM-DM floods and prunes multicast traffic assuming receivers everywhere, while PIM-SM only forwards toward explicit receivers

PIM-DM floods multicast traffic to all routers and then prunes branches without receivers, while PIM-SM uses explicit join messages and an RP, making it more scalable for WAN environments.

What is Bidirectional PIM (Bidir-PIM) and when is it preferred over PIM-SM?

Answer: A PIM mode where traffic flows in both directions along a shared tree, preferred for many-to-many multicast applications

Bidir-PIM builds a bidirectional shared tree rooted at the RP, allowing traffic to flow both toward and away from the RP, making it more scalable for many-to-many communication patterns.

In a dual-stack IPv6 deployment, what is the purpose of a DHCPv6 prefix delegation (DHCPv6-PD)?

Answer: Allows an ISP or upstream router to delegate an IPv6 prefix to a customer router for sub-allocation to its downstream interfaces

DHCPv6-PD (RFC 3633) enables an upstream device to delegate an IPv6 prefix (typically /48 or /56) to a CPE router, which then sub-delegates /64 prefixes to its LAN interfaces.