Frame Relay Flashcards
What was the problem with X.25 in the early 90s?
It was judged too slow due to high protocol overhead, slow switching, intensive error checking and recovery methods
T/F: changing partially-meshed networks was not dynamic or easy
True
What was the solution to X.25?
Frame Relay
What is a DLCI?
Data Link Connection Identifier. A logical identifier included in each frame.
How does Frame relay gain much of its speed?
Doing away with X.25 overhead
Does a Frame Relay node check the CRC prior to sending data to the next link?
No, CRC is performed at user accesses.
When is a virtual circuit defined as permanent?
When it is set up permanently with physical links and logical DLCIs predefined between two DTEs.
When is a virtual circuit defined as switched?
When the physical links and DLCI are dynamically assigned using a procedure (Frame Relay call setup establishment process) from a calling local DTE and a called remote DTE.
The switching nodes keep a map of these values.
How are SVC links and DLCI assignments dissolved?
After the call, either the calling or the called DTE initiates a call clearing procedure.
Name 5 service parameters included in the DLCI (from the Address field)
- frame size
- committed information rate (CIR)
- committed burst size (Bc)
- Burst Excess size (Be)
- committed Rate measured interval (Tc)
When using Frame and ATM, where is the conversion of frame to cells accomplished?
Ingress and egress points or nodes using IWF
What are the two numbering plans that the Frame Relay Forum recommends?
X.121 or E.164
What is a DNIC?
Data Network Identification Code - 4 unique digits for each public network
What is an NTN?
Network Terminal Number - 8- 10 digits for each UNI access line
What is the X.121 address?
1 + DNIC + NTN
What numbering plan is used for ISDN?
E.164
What is ISDN? What does it provide?
Integrated Services Digital Network. Provides voice, video, data over digital networks.
What two channels are used in ISDN? What are there associated letters?
D - signalling channels: set up, control, tear down calls
B - bearer channels: transmit info
What are the two types of ISDN services?
BRI: basic rate interface
PRI: primary rate interface
What is B-ISDN?
Broadband Integrated Services Digital Network to handle high-bandwidth applications such as video.
What technology is used in the backbone network when using Frame Relay?
ATM
What is the maximum size of the complete E.164 address?
55 digits
How fast is ISDN? B-SDN?
ISDN: up to 1.536 Mb/s
B-ISDN: up to 622 Mb/s
