QOS - FRTS

FRTS or Frame Relay Traffic shaping was intended as a replacement to GTS. It allows a more granular approach to QOS with shaping per VC.

Once traffic shaping is enabled on a physical interafce a CIR of 56kbps and a tc of 125ms applies. Configuration parameters are defined using the map-class frame-relay command and are then applied to the interface using frame-relay interface-dlci xxx.

In this example R3 and R5 and connected via a frame-relay circuit. The CIR is 256k, with bursts up to 384k permitted. R5 must not overwhelm R3 i.e. it must conform to the CIR of R3.

Router 3

map-class frame-relay DLCI_305
frame-relay cir 256000
frame-relay bc 2560
frame-relay be 1280

interface Serial2/0
frame-relay traffic-shaping
frame-relay interface-dlci 305
class DLCI_305

Router 5

map-class frame-relay DLCI_503
frame-relay cir 256000
frame-relay bc 2560
frame-relay be 0

interface Serial2/0
frame-relay traffic-shaping
frame-relay interface-dlci 503
class DLCI_503

Once applied the configuration can be verified with the show traffic-shape command


Router_3#show traffic-shape

Interface Se2/0
Access Target Byte Sustain Excess Interval Increment Adapt
VC List Rate Limit bits/int bits/int (ms) (bytes) Active
305 256000 480 2560 1280 10 320 -


FRTS employs a three tiered approach to queueing. The per vc queues, then the main interface queue, followed by the physical interface transmit ring. These can all be adjusted as follows

per vc FIFO: frame-relay holdq
interface FIFO: hold-queue
transmit-ring: tx-ring-limit