Frame Relay Flashcards
In a frame relay environment, what equipment is considered the DCE?
The frame relay switch
A name for the keepalive messages between the frame switch and the router.
LMI
What does LMI stand for?
Local Management Interface
In FR, what is the access link?
The leased line between FR switch and router.
What 2 organizations are the primary sources for FR standards?
ITU
ANSI
What does ITU stand for?
International Telecommunications Union
What does ANSI stand for?
American National Standards Institute
What’s the most common type of LMI packet?
Status inquiry
What are 2 functions of the LMI Status Inquiry packet?
- Keepalive between DCE and DTE.
- Signal up/down status of VCs.
List the 3 LMI types
- Cisco
- Ansi
- ITU
If you don’t set the LMI type on a frame interface, what does it default to?
It will auto-sense the LMI type that the switch is using.
What are the standards for the ANSI and ITU LMI types?
ANSI - T1.617 Annex D
ITU - Q.933 Annex A
Syntax for configuring Cisco, ANSI, or ITU LMI types.
frame-relay lmi-type {cisco | ansi | 933a}
Syntax to change interface s1/0 to from HDLC to frame relay.
conf t
interface s1/0
encapsulation frame-relay
What options are available for the “encapsulation frame-relay” command?
cisco
ietf
Command to associate an interface or subinterface with a given DLCI.
frame-relay interface-dlci *dlci* [ietf]
What is default mechanism used by a frame-relay router to map a DLCI to an IP address?
Inverse ARP
If not using InARP, what is the syntax to map a DLCI to an IP address?
frame-relay map ip *IP* *DLCI* broadcast
Is a DLCI globally significant or locally significant?
Locally significant. The DLCI for a PVC connecting 2 sites is likely to be different at each end.
What are the 6 steps of configuring a frame-relay interface, in non-syntax form and including optionals?
- Configure the interface with frame-relay encapsulation.
- Configure interface or subinterface with an IP address.
- Set the LMI type.
- Change encapsulation from cisco to ietf.
- Set the DLCI to IP address map(s).
- Bind the subinterface to either a single DLCI or (in a multipoint environment), to multiple DLCIs.
What are the 2 items absolutely needed for a frame relay interface to pass traffic?
- The encapsulation must be set to frame-relay.
- An IP address must be configured.
Why do DLCIs not need to be explicitly defined in simple frame relay implementations?
Because the DLCIs should be learned from LMI messages.
How does a configuration differ if all VC’s require ietf encapsulation vs just 1 single VC requiring it?
When all VC’s need ietf encapsulation, it can be configured at the interface level.
When individual VCs need ietf encapsulation, it can be set via the frame-relay interface-dlci or frame-relay map commands.
At what level of configuration is the lmi-type always configured?
At the physical interface level.
How does one disable auto-sensing of the LMI type?
By statically configuring the LMI type.
What command is used to see frame relay errors?
show frame-relay pvc
What frame relay command is used to see if a dlci is dynamic or static, and what it is?
show frame-relay map
R2#show frame map
Serial1/1 (up): ip 10.140.12.3 dlci 212(0xD4,0x3440), dynamic,
broadcast,
CISCO, status defined, active
What 2 commands can be used to see the LMI type?
show interface *interface*
show frame-relay lmi
What is the interface status if there is an LMI mismatch?
The interface will be up/down.
What will the output of the “show frame-relay pvc” command be if there is an lmi mismatch?
It will be blank. The interface will be up/down, and there will be no signalling to create any dynamic pvc’s.
Command to create subinterface 15 on s1/1 connecting to 1 router.
conf t
int s1/1.15 point-to-point
