Information Technology Reference
In-Depth Information
Frame Relay Forum 12 on Slow-Speed Frame Relay Links (768 Kbps or Less)
Frame Relay Forum 12 (FRF.12) is similar to MLP LFI but operates on Frame Relay interfaces.
Cisco has a number of recommendations with regard to voice and Frame Relay:
■
Enable FRF.12 (fragment size for 10 ms) and cRTP for circuits less than or equal to 768 Kbps.
■
The committed information rate (CIR) should be set to 95 percent of the PVC contracted speed.
■
The committed burst (Bc) should be set to CIR/100 (nondistributed platforms) or CIR/125 (distributed platforms).
■
The excess burst (Be) should be set to 0.
The configuration of FRF.12 is quite different from that for MLP LFI, as shown in the following example (for a 768-Kbps circuit):
interface serial 1/0.10 point-to-point
ip address
10.1.1.1 255.255.255.0
frame-relay interface-dlci
100
class
frf-12
!
map-class frame-relay
frf-12
frame-relay fragment
960
The
frame-relay fragment
command enables fragmentation and interleaving of Frame Relay frames and specifies the fragment size
in bytes.
The following example uses the Modular QoS CLI (MQC), and is again for a 768-Kbps circuit:
policy-map fr-shaping
class class-default
shape average 729600 7296 0
service-policy slow-wan
!
map-class frame-relay slow-wan-class
service-policy output fr-shaping
frame-relay fragment 960
!
interface Serial1/0
no ip address
