Get ECP-206 Dumps : Verified Ericsson Certified Associate - IP Networking

P routers forward packets based on the LSP label. The LSP label is the label that corresponds to the label-switched path (LSP) that is established between two PE routers in an MPLS network. The LSP label is also called the outer label or the transport label, because it is used to transport packets across the MPLS core network. P routers are also called LSRs (label switch routers) or transit routers, because they switch packets based on their labels or remove the labels. P routers do not need to look at the IP header or any other information in the packet, except for the top label in the label stack. P routers perform one of three possible operations on labels: swap, pop, or PHP (penultimate hop popping). In a swap operation, the label is swapped with a new label, and the packet is forwarded along the path associated with the new label. In a pop operation, the label is removed from the packet, and the packet is forwarded based on its IP header or another label in the stack. In a PHP operation, the label is removed from the packet at the last P router before reaching the egress PE router, and the packet is forwarded without any label to the egress PE router.

The LSP label is different from other types of labels that may be used in MPLS networks, such as VPN labels or service labels. These labels are used to identify different VPNs or services that run over MPLS networks, such as Layer 2 VPNs, Layer 3 VPNs, traffic engineering, or QoS. These labels are also called inner labels or payload labels, because they are related to the payload of the packet. These labels are not used by P routers for forwarding decisions, but only by PE routers for delivering packets to their destinations.

Therefore, the answer is C.

References: Ericsson IP Networking - Routing Protocols, MPLS Fundamentals: Forwarding Labeled Packets - Cisco Press, MPLS Labels and Devices - NetworkLessons.com, Multiprotocol Label Switching - Wikipedia, VPN Packet Forwarding > MPLS/VPN Architecture Overview | Cisco Press, Basic concepts - Hewlett Packard Enterprise

LDP relies on IGP for all routing-related decisions. LDP is a protocol that distributes labels in an MPLS environment, but it does not perform any routing functions. LDP uses the underlying routing information provided by an IGP, such as OSPF or IS-IS, to forward label packets. LDP and IGP do not exchange their databases at regular intervals, but rather use hello messages to maintain adjacencies and sessions. References: Ericsson IP Networking - Routing Protocols, Label Distribution Protocol - Wikipedia

Referring to the exhibit, the correct statement is that the service provider’s P routers are not aware of the customers’ routes. This is because P routers only need to forward MPLS packets based on their labels, without looking into their IP headers or VPN information. The P routers do not have any VRFs configured for the customers, nor do they participate in MP-BGP sessions with other PE routers. The PE routers are responsible for maintaining VRFs for each customer and for exchanging VPN routes with other PE routers using MP-BGP910.

References: Layer 3 VPNs (L3VPN) - Cisco, MPLS VPN - Wikipedia

Route summarization is a technique that reduces the number of routes that a router advertises to its neighbors by creating a single summary route that covers multiple subnets or networks. Route summarization has several benefits, such as:

• It reduces the size of a routing table, which saves memory and CPU resources on the router. A smaller routing table also improves the lookup efficiency and convergence time of the routing protocol.
• It reduces signaling, which means that less bandwidth is consumed by routing updates and less processing is required by neighboring routers. This also enhances the stability and scalability of the network, as fewer routing changes are propagated.
• It improves route aggregation, which means that more specific routes are replaced by a less specific route that can be advertised to other autonomous systems or routing domains. This simplifies the inter-domain routing and hides the internal topology details.

Route summarization does not necessarily summarize the routing table entries into a default route, although a default route can be considered a special case of route summarization where all destinations are covered by one route. Route summarization also does not improve the best route calculation, as it may introduce suboptimal routing or black holes if not done properly. References: Introduction to Route Summarization - NetworkLessons.com, Route Summarization > Example for Understanding Route Summarization - Cisco Press

Two roles of the DHCP protocol in a network are:

• It is used by hosts to obtain the IP address and other parameters from the DHCP server. DHCP stands for Dynamic Host Configuration Protocol, which is a protocol that provides automatic and centralized management of IP addresses and other network configuration parameters for devices connected to a network. A host that needs an IP address can send a request to a DHCP server, which will assign an available IP address from a pool and lease it to the host for a certain period of time34.
• It is used to inform hosts about the default gateway. The default gateway is the IP address of the router that connects the host to other networks. The default gateway is one of the parameters that can be delivered by the DHCP server to the host, along with other parameters such as subnet mask, DNS server, domain name, etc. The host can use the default gateway to send packets to destinations outside of its local network34.

References: What Is DHCP? (Dynamic Host Configuration Protocol) - Lifewire, Dynamic Host Configuration Protocol - Wikipedia