Ericsson ECP-206 - Ericsson Certified Associate - IP Networking

Two statements that are true about the Ericsson Router 6000 series are:

The Router 6000 uses the same building practice and accessories as the Ericsson Radio System. The Ericsson Radio System is a modular and scalableradio access network solution that supports multiple standards, bands, and layers. The Router 6000 series is fully integrated into the Ericsson Radio System, using the same building practice and accessories such as mounting kits, cables, power supplies, etc. This simplifies installation, operation, and maintenance of both radio and transport equipment78.

The Router 6000 products range from all-outdoor small site routers to large aggregation routers. The Router 6000 series consists of three main products: the Router 6672 for access, the Router 6675 for pre-aggregation, and the Router 6274 for metro aggregation. The Router 6672 is an all-outdoor small cell site router with high-capacity and low-power consumption. The Router 6675 is a combined access and E-RAN switch with hardware-accelerated IPSec and high-accuracy internal clock. The Router 6274 is a high-capacity metro aggregation router with SDN functionality and flexible interface options78.

References: Router 6000 Series - Ericsson, New Ericsson Router 6000 series couples radio and IP transport for 5G future - Global Brands Magazine

Regarding the BGP decision algorithm, two statements that are correct are:

A higher local-preference attribute will be favored over a lower local-preference attribute. The local-preference attribute is used by BGP routers within an AS to indicate their preference for an exit point from the AS. A higher value means a more preferred path. The local-preference attribute is exchanged only between iBGP peers and does not leave the AS boundary89.

A path cannot be considered if the next-hop is inaccessible. The next-hop attribute is used by BGP routers to determine where to forward packets for a given destination prefix. The next-hop attribute is usually set to the IP address of the eBGP neighbor that advertises the prefix. If there is no IGP route to reach the next-hop address, the path is marked as invalid and ignored by BGP1011.

The other two statements are incorrect because:

The most important criteria is not the administrative distance, but rather the weight attribute. The administrative distance is used by routers to choose between routes from different routing protocols, not within BGP. The weight attribute is a Cisco-specific attribute that is used by BGP routers to prefer one path over another within the same router. The weight attribute is local to the router and not advertised to any peers1213.

A lower local-preference attribute will not be favored over a higher local-preference attribute, as explained above.

References: BGP Best Path Selection Algorithm - Cisco, Understanding BGP Local Preference Attribute - NetworkLessons.com, BGP Next Hop Attribute Explained - NetworkLessons.com, BGP Next Hop Processing - Cisco Press, BGP Weight Attribute Explained - NetworkLessons.com, Understanding BGP Weight Attribute - Cisco Community

A label-edged router (LER) is a PE router. A PE router is a provider edge router, which is a router that connects an MPLS network to a customer network. A LER is a term used in MPLS to describe a router that resides at the ingress and egress points of an MPLS network, handling both labelled and unlabelled packets. A LER performs label operations such as adding, removing, or swapping labels on packets entering or leaving the MPLS network34.

References: What is Label Edge Router (LER)? - Definition from Techopedia, LER - Label Edge Router - Mpirical

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.

References: Ldp | Microsoft Learn, Label Distribution Protocol - Wikipedia

The correct ordering (outer to inner) of packet headers in an IP/MPLS packet is Ethernet, MPLS, IP. An IP/MPLS packet is a packet that is encapsulated with an MPLS label stack between the Ethernet header and the IP header. The Ethernet header contains the source and destination MAC addresses and the EtherType field that indicates the type of the payload. The MPLS label stack contains one or more labels that are used for forwarding decisions by the MPLS routers. Each label consists of four fields: label value, experimental bits, bottom of stack, and time to live. The IP header contains the source and destination IP addresses and other information for routing and fragmentation. The order of the headers is important because it determines how the packet is processed by different devices in the network12.

References: MPLS Label Stack - Cisco, MPLS Fundamentals: 3 - MPLS Packet Forwarding

In an Ethernet frame carrying a VLAN tag, the VLAN tag appears before the type field. A VLAN tag is a 4-byte field that is inserted into an Ethernet frame to indicate the VLAN membership and priority of the frame. The VLAN tag consists of two subfields: the tag protocol identifier (TPID) and the tag control information (TCI). The TPID subfield is a 16-bit field that identifies the frame as an IEEE 802.1Q-tagged frame, with a value of 0x8100. The TCI subfield is a 16-bit field that contains the priority code point (PCP), the drop eligible indicator (DEI), and the VLAN identifier (VID). The VLAN tag appears between the source MAC address and the type fields of the original frame, shifting the type field by four bytes. The type field indicates the type of the payload, such as IP or ARP .

References: [IEEE 802.1Q - Wikipedia], [VLAN Tagging Explained with DTP Protocol - GeeksforGeeks]

The router function that advertises external routes in OSPF is ASBR, which stands for Autonomous System Boundary Router. An ASBR is a router that connects an OSPF domain to another routing domain, such as another OSPF domain or a different routing protocol domain. An ASBR can redistribute routes from other routing domains into OSPF as external routes, which are carried in type 5 or type 7 LSAs. External routes have two types: E1 and E2. E1 routes include the cost from the ASBR to the destination, while E2 routes only include the cost advertised by the ASBR34.

References: OSPF External Routes ⋆ IpCisco, OSPF External Route selection algorithm - Cisco Community

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 is10.57.126.152. References: Ericsson IP Networking - IP Addressing, Software Installation and Upgrade Overview (Junos OS)

According to RFC1918, there are three network blocks reserved as private networks that are not allocated to any specific organization and are not routable on the public Internet. These are:

10.0.0.0/8 (10.0.0.0 - 10.255.255.255)

172.16.0.0/12 (172.16.0.0 - 172.31.255.255)

192.168.0.0/16 (192.168.0.0 - 192.168.255.255)

Out of these, only option B (10.254.1.0/24) falls within one of the private network blocks (10.0.0.0/8). Option A (172.16.1.0/9) is not valid because it exceeds the /12 prefix length of the private network block (172.16.0.0/12). Option C (193.168.1.0/24) is not valid because it does not belong to any of the private network blocks, and is actually assigned to RIPE NCC as a public network block . Option D (172.15.1.0/24) is also not valid because it does not belong to any of the private network blocks, and is actually assigned to ARIN as a public network block . References: RFC 1918: Address Allocation for Private Internets, Private network - Wikipedia, [RIPE NCC IPv4 Address Space Chart], [ARIN WHOIS Database Search]