| A | B |
|---|
| Frame Relay frame field: Flag | Frame Relay frame fields: |
| Frame Relay frame field: Address | Indicates the length of the Address field. |
| Frame Relay addresses are currently all _____ bytes long | 2 |
| The _______ bit of each byte of the Address field is used to indicate the address. | eighth |
| The Address contains the following information | DLCI Value, Congestion Control |
| DLCI Value | Consists of the first 10 bits of the Address field |
| Congestion Control | The last 3 bits in the address field, which control the FECN, BECN, and discard eligible (DE) bits |
| Frame Relay frame field: Data | Variable-length field that contains encapsulated upper-layer data. |
| Frame Relay frame field: FCS (Frame check sequence) | used to ensure the integrity of transmitted data |
| DLCI address space is limited to ______ bits | 10 |
| There are a possible _______ DLCI addresses | 1024 |
| The usable portion of the DLCI addresses are determined by | the LMI type used. |
| The Cisco LMI type supports a range of DLCI addresses from DLCI 16-1007 for | carrying user-data |
| The DLCI addresses not used for carrying user-data are | reserved for vendor implementation. |
| The network uses ____ to keep the two locally significant PVC identifiers distinct | internal mechanisms |
| Local Management Interface (LMI) | Set of enhancements to the basic Frame Relay specification. |
| LMI includes support for a keepalive mechanism, which | verifies that data is flowing |
| LMI includes support for a multicast mechanism, which | provides the network server with its local DLCI and the multicast DLCI |
| LMI includes support for global addressing, which | gives DLCIs global rather than local significance in Frame Relay networks |
| LMI includes support for a status mechanism, which | provides an on-going status report on the DLCIs known to the switch |
| The main functions of LMI process are: | determine the operational status of the various PVCs , transmit keepalive packets to ensure that the PVC stays up , tell the router what PVCs are available |
| Three LMI types can be invoked by the router: | ansi, cisco, and q933a |
| Frame Relay specification includes LMI extensions referred to as common are | expected to be implemented by everyone who adopts the specification. |
| Frame Relay specification includes LMI extensions referred to as optional are | not expected to be implemented by everyone |
| LMI extensions:Virtual circuit status messages (common) | Provide communication and synchronization between the network and the user device, periodically reporting the existence of new PVCs and the deletion of already existing PVCs, and providing general information about PVC integrity |
| Virtual circuit status messages prevent the sending of | data over PVCs that no longer exist. |
| LMI extensions: Multicasting (optional) | Allows a sender to transmit a single frame but have it delivered by the network to multiple recipients. |
| Multicasting supports the efficient conveyance of routing protocol messages and address resolution protocols that typically | must be sent to many destinations simultaneously |
| LMI extensions: Global addressing (optional) | Gives connection identifiers global rather than local significance, allowing them to be used to identify a specific interface to the Frame Relay network. |
| Global addressing makes the Frame Relay network resemble a local-area network (LAN) in terms of addressing; address resolution protocols therefore | perform over Frame Relay exactly as they do over a LAN. |
| LMI extensions: Simple flow control (optional) | Provides for an XON/XOFF flow control mechanism that applies to the entire Frame Relay interface |
| Global addressing makes the Frame Relay network resemble a | local-area network (LAN) in terms of addressing; |
| The LMI frame format contain ___ mandatory bytes | 4 |
| The LMI frame message type field has these two message types defined | status messages and status-enquiry messages |
| Together, status and status-enquiry messages help verify the | integrity of logical and physical links |
| routing protocols make decisions based on | link integrity |
