CCNA Cisco Certified Network Associate Study Guide - FTP Server

Frame Relay 501
really might need. This is called the Committed Information Rate (CIR).
What this means is that the customer can buy bandwidth of, for example,
256k, but it is possible to burst up to T-1 speeds. The CIR specifies that as
long as the data input by a device to the Frame Relay network is below or
equal to the CIR, then the network will continue to forward data for the
PVC. However, if data rates exceed the CIR, it is not guaranteed.
It is sometimes possible to also purchase a Bc (Committed Burst), which
allows customers to exceed their CIR for a specified amount of time. In this
situation, the DE bit will always be set.
Choose a CIR based on realistic, anticipated traffic rates. Some Frame
Relay providers allow you to purchase a CIR of zero. You can use a zero CIR
to save money if retransmission of packets is acceptable. However, understand
that the DE bit will always be turned on in every frame.
Monitoring Frame Relay
There are several ways to check the status of your interfaces and PVCs once
you have Frame Relay encapsulation set up and running:
RouterA>sho frame ?
ip show frame relay IP statistics
lmi show frame relay lmi statistics
map Frame-Relay map table
pvc show frame relay pvc statistics
route show frame relay route
traffic Frame-Relay protocol statistics
Show Frame-Relay Lmi
The show frame-relay lmi command will give you the LMI traffic statistics
exchanged between the local router and the Frame Relay switch.
Router#sh frame lmi
LMI Statistics for interface Serial0 (Frame Relay DTE) LMI TYPE
= CISCO
Invalid Unnumbered info 0 Invalid Prot Disc 0
Invalid dummy Call Ref 0 Invalid Msg Type 0
Invalid Status Message 0 Invalid Lock Shift 0