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27
M
UTLILINK
F
RAME
R
ELAY
27.1Multilink Frame Relay FRF.15 and FRF.16
Multilink Frame Relay (MFR) is actually composed of two standards: FRF.15 and FRF.16. The latter is more common
and defines UNI/NNI interfaces for implementing MFR. FRF.16 is used for multiplexing dedicated T1s in the local
loop and requires compatible equipment at the carrier POP. FRF.15, or DTE-to-DTE MFR is used for multiplexing
frame relay T1s between end points without impacting POP equipment. As a result, FRF.15 can be implemented across
multiple frame relay carriers to provide additional redundancy. This application discusses considerations for using this
standard. All Black Box products support FRF.15 and FRF.16.
27.1.1 Features
Low cost way of providing added bandwidth to private networks
Can be done without the knowledge of the Frame Relay provider
Scalable bandwidth using MFR for customers based on T1 access
Traffic can be routed or switched using Frame Relay at the end points
A customer desiring to implement DTE-to-DTE MFR can use the architecture illustrated in Figure 1. The normal
ordering process can be used to obtain the fame relay T1s. From the perspective of the CPE, the Black Box LR1114As
combine those different frame relay PVCs into a consolidated, larger pipe.
FRF.15 uses an aggregated virtual circuit (AVC) for the combined interface. The AVC is composed of constituent
virtual circuits (CVC) that represent the frame relay T1s ordered from the carrier(s). In this example, the Black Box
LR1114As are configured with DTE LMI; the carrier frame switches are DCE.
Figure 44 MFR Using FRF.15
In Black Box systems, CVCs are configured using the bundle construct normally used for a non-ethernet interface.
After the CVCs are configured, they can be assigned to the AVC. The AVC, frf15 in this case, is assigned a DLCI of
100 on both ends and an IP address in the 11.1.1.0/30 subnet. The AVC names and DLCI numbers can be different on
Frame
Switch
Frame
Switch
Tasman 1400
Tasman 1400
Frame Relay
Backbone
T
1 Bundle DLCI
1
cvc1 101
2
cvc2 102
3
cvc3 103
avc frf15
DLCI 100
ip addr 11.1.1.1/30
avc frf15
DLCI 100
ip addr 11.1.1.2/30
T1 Bundle DLC
I
1 cvc1 101
2 cvc2 102
3 cvc3 103
LR1114A
LR1114A