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)
Question 2
How is a BGP session established between two routers?
Options:
A.
The BGP router sends a unicast NOTIFICATION message.
B.
The BGP router sends a unicast OPEN message.
C.
The BGP router sends a multicast CONNECT message.
D.
The BGP router sends a multicast HELLO packet.
Answer:
B
Explanation:
Explanation:
A BGP session is established between two routers by sending a unicast OPEN message. BGP uses TCP as its transport protocol, which means that before exchanging any BGP information, a TCP connection must be established between the routers. The TCP connection uses port 179 as both source and destination port. After establishing a TCP connection, each router sends an OPEN message to its neighbor, containing parameters such as BGP version number, AS number, hold time, BGP identifier, and optional capabilities. The OPEN message also serves as a keepalive message for BGP. If both routers agree on these parameters, they proceed to exchange UPDATE messages containing routing information and establish a BGP session.
A BGP router does not send a NOTIFICATION message to establish a session, but rather to terminate a session due to an error or a manual shutdown. A BGP router does not send a CONNECT message, as this is a TCP state, not a BGP message. A BGP router does not send a multicast HELLO packet, as this is an OSPF message, not a BGP message. References: BGP Neighbor States > BGP Fundamentals | Cisco Press, Demystifying BGP Session Establishments - Packet Pushers, The TCP/IP Guide - BGP Connection Establishment: Open Messages
Question 3
What is the purpose of the RT attribute?
Options:
A.
to identify the destination VPN on the efress PE
B.
to prevent OSPF routing loops in an L3VPN environment
C.
to indicate an MPLS LSP as the next hop routing target
D.
to request BGP neighbors to avoid routing through a private AS
Answer:
A
Explanation:
Explanation:
The purpose of the RT attribute is to identify the destination VPN on the egress PE. RT stands for route target, which is a BGP extended community attribute that is used in MPLS VPNs. RT is attached to VPN routes by the ingress PE router and is used to control the import and export of routes between different VPNs. The egress PE router uses the RT value to determine which VPN routes belong to which VPN customers and installs them in the appropriate VRF table56.
References: IP Routing: BGP Configuration Guide - BGP-RT and VPN … - Cisco,