session1, part2. carrier ethernet and Ethernet Transport Fundamentals

C. Enables Ethernet to be deployed in large complex networks

• B. Ethernet has high bandwidth capabilities
• C. Ethernet is a low cost solution compared to other technologies

• A. Ethernet service management
• C. Supports large networks that spans metro, national, and international 
• D. Standardized services

• B. A set of standardized services transported over the network
• D. A set of network elements that make up the Ethernet Transport

• A. Provides a certification program to ensure interoperability of networks and services
• C. Global alliance of Service Providers and network vendors
• D. Organization defining Carrier Ethernet networks and services

• C. It is difficult to manage Ethernet over multiple operatordomains
• D. Provider needs a way to manage end to end connectivity

• A. E-LAN
• B. E-Tree
• D. E-Line

• A. Mobile Backhaul
• C. Data Center point to point E-Line connection
• D. Triple Play Backhaul

A. 802.21ah

Provider Backbone Bridges (PBB, known as "mac-in-mac") is a set of architecture and protocols for routing over a provider's network allowing interconnection of multiple Provider Bridge Networks without losing each customer's individually defined VLANs.

The idea of PBB is to offer complete separation of customer and provider domains. For this purpose, a new Ethernet header has been defined.

D. There is only one active patch between any two points

The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of bridge loops, or the need for manual enabling/disabling of these backup links.

D. BPDU (Bridge Protocol Data Units)

A bridge sends a BPDU frame using the unique MAC address of the port itself as a source address, and a destination address of the STP multicast address 01:80:C2:00:00:00.

• There are three types of BPDUs:
• Configuration BPDU (CBPDU), used for Spanning Tree computation
• Topology Change Notification (TCN) BPDU, used to announce changes in the network topology
• Topology Change Notification Acknowledgment (TCA)

BPDUs are exchanged regularly (every 2 seconds by default) and enable switches to keep track of network changes and to start and stop forwarding at ports as required.

C. Root Port

The bridges have to determine the root bridge and compute the port roles (root, designated, or blocked) with only the information that they have. To ensure that each bridge has enough information, the bridges use special data frames called Bridge Protocol Data Units (BPDUs) to exchange information about bridge IDs and root path costs.

B. 802.1qay

Provider Backbone Bridge Traffic Engineering (PBB-TE) is an approved telecommunications networking standard, IEEE 802.1Qay-2009.PBB-TE adapts Ethernet technology to carrier class transport networks. It is based on the layered VLAN tags and MAC-in-MAC encapsulation defined in IEEE 802.1ah (Provider Backbone Bridges (PBB)), but it differs from PBB in eliminating flooding, dynamically created forwarding tables, and spanning tree protocols.

B. 4096 in total

IEEE 802.1Q is the networking standard that supports Virtual LANs (VLANs) on an Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the accompanying procedures to be used by bridges and switches in handling such frames. The standard also contains provisions for a quality of service prioritization scheme commonly known as IEEE 802.1p and defines the Generic Attribute Registration Protocol.

C. Spanning Tree Disabled

A. TRUE

B. Flush FDB Message

Ethernet Ring Protection Switching, or ERPS, is an effort at ITU-T under G.8032 Recommendation to provide sub-50ms protection and recovery switching for Ethernet traffic in aring topology and at the same time ensuring that there are no loops formed at the Ethernet layer. G.8032v1 supported a single ring topology and G.8032v2 supports multiple rings/ladder topology.

B. 48

A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies, including Ethernet. Logically, MAC addresses are used in the Media Access Control protocol sub-layer of the OSI reference model.

A. Master

B. Data Link

• The data link layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer. 
• Practical, connectionless LANs began with the pre-IEEE Ethernet specification, which is the ancestor of IEEE 802.3. This layer manages the interaction of devices with a shared medium, which is the function of a media access control (MAC) sublayer. Above this MAC sublayer is the media-independent IEEE 802.2 Logical Link Control (LLC) sublayer, which deals with addressing and multiplexing on multiaccess media.

A. Half Duplex

A hub works at the physical layer (layer 1) of the OSI model.[1] The device is a form of multiport repeater. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision.

• C. Redundancy
• D. Increased Bandwidth

Link aggregation is a computer networking term to describe various methods of combining (aggregating) multiple network connections in parallel to increase throughput beyond what a single connection could sustain, and to provideredundancy in case one of the links fails.

C. Dedicated

• Rapid Spanning Tree Operation
• RSTP adds new bridge port roles in order to speed convergence following a link failure.

• RSTP bridge port roles:
• Root - A forwarding port that is the best port from Nonroot-bridge to Rootbridge
• Designated - A forwarding port for every LAN segment
• Alternate - An alternate path to the root bridge. This path is different than using the root port.
• Backup - A backup/redundant path to a segment where another bridge port already connects.
• Disabled - Not strictly part of STP, a network administrator can manually disable a port

A. Listening

• STP switch port states:
• Blocking - A port that would cause a switching loop, no user data is sent or received but it may go into forwarding mode if the other links in use were to fail and the spanning tree algorithm determines the port may transition to the forwarding state. BPDU data is still received in blocking state. Prevents the use of looped paths.
• Listening - The switch processes BPDUs and awaits possible new information that would cause it to return to the blocking state. It does not populate the MAC address table and it does not forward frames.
• Learning - While the port does not yet forward frames it does learn source addresses from frames received and adds them to the filtering database (switching database). It populates the MAC Address table, but does not forward frames.
• Forwarding - A port receiving and sending data, normal operation. STP still monitors incoming BPDUs that would indicate it should return to the blocking state to prevent a loop.
• Disabled - Not strictly part of STP, a network administrator can manually disable a port

D. Between the Source Address and type field

D. LACP

Within the IEEE specification the Link Aggregation Control Protocol (LACP) provides a method to control the bundling of several physical ports together to form a single logical channel. LACP allows a network device to negotiate an automatic bundling of links by sending LACP packets to the peer (directly connected device that also implements LACP).

B. Collisions

A. in hardware

B. in software

B. Source Address

A. Ethernet has no Time To Live Field

• Ethernet frame:
• 

D. Listening

• STP switch port states:
• Blocking - A port that would cause a switching loop, no user data is sent or received but it may go into forwarding mode if the other links in use were to fail and the spanning tree algorithm determines the port may transition to the forwarding state. BPDU data is still received in blocking state. Prevents the use of looped paths.
• Listening - The switch processes BPDUs and awaits possible new information that would cause it to return to the blocking state. It does not populate the MAC address table and it does not forward frames.
• Learning - While the port does not yet forward frames it does learn source addresses from frames received and adds them to the filtering database (switching database). It populates the MAC Address table, but does not forward frames.
• Forwarding - A port receiving and sending data, normal operation. STP still monitors incoming BPDUs that would indicate it should return to the blocking state to prevent a loop.
• Disabled - Not strictly part of STP, a network administrator can manually disable a port

• RSTP:
• As of RSTP, the protocol now includes not only states (learning, forwarding and discarding) and roles (designated, root, alternate, backup (and master for MST)).
• Basically, the state have been simplified: listening and blocking are now just "discarding". These three mean exactly the same from an operational point of view. It's just that we kept the old naming in our implementation. So you can still see the difference between listening and blocking, which is of little use in fact