CCIE Service Provider Flashcards

In MPLS L3VPN, which protocol is used to distribute VPN labels and VPNv4 routes between PE routers?

Answer: MP-BGP

Multiprotocol BGP (MP-BGP) with the VPNv4 address family distributes customer routes and associated VPN labels between PE routers across the MPLS backbone.

What is the purpose of a Route Distinguisher (RD) in MPLS L3VPN?

Answer: Making overlapping customer IP prefixes unique in the BGP table

An RD prepended to customer IPv4 prefixes creates unique VPNv4 routes, allowing BGP to differentiate between identical prefixes from different VPN customers.

What mechanism in MPLS service provider networks controls which VPN routes are imported/exported between VRFs?

Answer: Route Target (RT) community

Route Targets are BGP extended communities used to control VPN route import and export between VRFs, determining which sites can communicate.

In a service provider network, which IS-IS level is used for routing within a single area?

Answer: Level 1

IS-IS Level 1 routing handles intra-area routing within a single IS-IS area, analogous to OSPF intra-area routing.

What is the function of RSVP-TE (Resource Reservation Protocol - Traffic Engineering) in MPLS networks?

Answer: Signaling LSPs with bandwidth reservations for traffic engineering

RSVP-TE signals explicitly-routed Label Switched Paths (LSPs) with bandwidth reservations, enabling traffic engineering in MPLS networks.

Which BGP feature allows ISPs to aggregate customer routes and prevent specific customer prefixes from being advertised to the internet?

Answer: BGP aggregate-address with summary-only

The 'aggregate-address' command with 'summary-only' suppresses more-specific component routes and advertises only the aggregate to reduce internet routing table size.