Ericsson ECP-206 Exam Dumps

A P router is a provider router that is part of the service provider's core network in an MPLS environment. A P router does not have any customer routes or VPN information, but only has information about how to reach other P routers and PE routers in the same MPLS domain. A P router performs label switching, which means that it forwards labeled packets based on their top label in the label stack. A P router can perform two possible label actions:

Swap: The P router replaces the incoming label with a new label that corresponds to the next hop along the label-switched path (LSP). The new label is determined by looking up the label forwarding information base (LFIB) based on the incoming label and interface.

PHP: The P router removes the top label from the packet at the penultimate hop before reaching the egress PE router. This is done to avoid an extra lookup on the egress PE router, which can forward the packet based on its IP header or another label in the stack.

A P router does not perform push or drop actions on labels. A push action means adding one or more labels to the packet, which is done by an ingress PE router when initiating an LSP. A drop action means discarding a packet, which is done by any router when there is no matching entry in its LFIB or routing table.Reference:Provider (P) Router in IP MPLS Network - Cisco Community,MPLS Fundamentals: Forwarding Labeled Packets - Cisco Press,MPLS Label Switching | MPLS Operation | Push, Swap,Push IPCisco

The subnet address for 10.57.126.156/29 is 10.57.126.152. To find the subnet address, we need to perform a bitwise AND operation between the IP address and the subnet mask. The subnet mask for /29 is 255.255.255.248, which in binary is 11111111.11111111.11111111.11111000. The IP address in binary is 00001010.00111001.01111110.10011100. The result of the AND operation is 00001010.00111001.01111110.10011000, which in decimal is 10.57.126.152.Reference:Ericsson IP Networking - IP Addressing,Software Installation and Upgrade Overview (Junos OS)

IPv6 link-local addresses are designed to be used in three situations: for neighbor discovery, for local IP communication on the IPv6 capable routers, and for addressing on a single link for purposes such as auto-address configuration. Neighbor discovery is a protocol that allows IPv6 nodes to discover each other and learn their link-layer addresses on a local network.Neighbor discovery uses link-local addresses to send and receive messages such as router advertisements, router solicitations, neighbor advertisements, and neighbor solicitations34. Local IP communication on the IPv6 capable routers refers to the ability of routers to exchange routing information or management traffic using their link-local addresses as source and destination addresses.This reduces the need for global unicast addresses on router interfaces that are not reachable from outside the local network35. Addressing on a single link for purposes such as auto-address configuration refers to the use of link-local addresses to enable IPv6 nodes to obtain an address without manual configuration or a DHCP server. Link-local addresses can be automatically derived from the interface identifier in the modified EUI-64 format or randomly generated.Link-local addresses can also be used to test the connectivity of a link before obtaining a global unicast address36.

Two statements that are correct for LDP are:

LSRs send UDP hello messages for neighbor discovery. LDP is a protocol that distributes labels for MPLS forwarding along the shortest path calculated by an IGP. LDP uses two types of messages: discovery messages and session messages. Discovery messages are used to discover and maintain adjacency with other LSRs that support LDP.Discovery messages are sent as UDP datagrams to the well-known multicast address 224.0.0.2 (all routers on this subnet) on port 64634.

LSRs use TCP to negotiate LDP session parameters. Session messages are used to establish, maintain, and terminate LDP sessions between LSRs. Session messages are also used to exchange label mappings, notification messages, and keepalive messages.Session messages are sent as TCP segments to port 64634.

Link-state routing protocols are one of the two main classes of routing protocols used in packet switching networks for computer communications, the other being distance-vector routing protocols. Examples of link-state routing protocols include Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS). The basic concept of link-state routing is that every node constructs a map of the connectivity to the network, in the form of a graph, showing which nodes are connected to which other nodes. Each node then independently calculates the next best logical path from it to every possible destination in the network. Each collection of best paths will then form each node's routing table.

Two statements that are true about link-state routing protocols are:

The advertisement exchange is mainly triggered by a change in the network. Link-state routing protocols use a flooding mechanism to distribute information about the network topology to all routers in the same area or domain. This information is encapsulated in link-state packets (LSPs) or link-state advertisements (LSAs), which contain information about the router, its directly connected links, and the state of those links. LSPs or LSAs are sent only when there is a change in the topology, such as a link failure or recovery, or when a periodic refresh timer expires. This way, link-state routing protocols can quickly adapt to network changes and maintain an accurate and consistent view of the network.

Each router uses a reliable update mechanism to exchange topology information with its neighbors. Link-state routing protocols use a reliable update mechanism to ensure that all routers receive and acknowledge the LSPs or LSAs sent by their neighbors. This mechanism involves sending hello messages to establish and maintain adjacencies with neighbors, sending acknowledgment messages to confirm the receipt of LSPs or LSAs, and requesting missing or outdated LSPs or LSAs from neighbors. This mechanism ensures that all routers have a synchronized database of LSPs or LSAs, which is used to build a complete network connectivity map and to calculate the shortest path to destinations.