Frame relay QoS

MQC_Based Frame relay traffice shaping:

In summary:

- Legacy command frame-relay traffic-shaping is incompatible with MQC-based FRTS (you can’t mix them)
- Fancy queueing could not be used as a PVC-queueing strategy: CBWFQ is the only option available
- Per-VC CBWFQ is configured via hierarchical policy-maps configuration: Parent policy sets shaping values, while child policy implements CBWFQ
- You may apply policy-map per-interface (subinterface) or per-VC, using match fr-dlci under class-map submode
- You can’t apply FRF.12 fragmentation with MQC commands – it should be applied at physical interface level. By doing so, FRF.12 is effectively enabled for all PVCs
- Physical interface queue could be set to any of WFQ/CQ/PQ or CBWFQ (not restricted to FIFO as with FRTS legacy) – though this is rarely needed

Sample: Shape PVC DLCI 112 to 384Kpbs and enable FRF.12 fragmentation for all PVCs

class-map VOICE
match ip dscp ef
!
class-map DATA
match ip dscp cs1

!
! Match the specific DLCI
!
class-map DLCI_112
match fr-dlci 112

!
! "Child" policy-map, used to implement CBWFQ
!

policy-map CBWFQ
class VOICE
priority 64
class DATA
bandwidth 128
class class-default
fair-queue

!
! "Parent" policy map, used for PVC shaping
! With multiple classes, we can match different DLCIs
! all at the same physical interface (where they belongs)
!

policy-map INTERFACE_POLICY
class DLCI_112
shape average 384000
shape adaptive 192000
service-policy CBWFQ

!
! Apply the parent policy map at physical interface level
! Also, configure FRF.12 "global" settings here
!

interface Serial 0/0/0
service-policy output INTERFACE_POLICY
frame-relay fragment 640 end-to-end


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Legacy Frame Relay traffic shaping:

- Enabled with frame-relay traffic-shaping command at physical interface level
- Incompatible with GTS or MQC commands at subinterfaces or physical interface levels
- With FRTS you can enforce bitrate per-VC (VC-granular, unlike GTS), by applying a map-class to PVC
- When no map-class is explicitly applied to PVC, it’s CIR and Tc are set to 56K/125ms by default
- Shaping parameters are configured under map-class frame-relay configuration submode
- Allows to configure fancy-queueing (WFQ/PQ/CQ) or simple FIFO per-VC
- No option to configure fancy-queueing at interface level: interface queue is forced to FIFO (if no FRF.12 is configured)
- Allows for adaptive shaping (throttling down to minCIR) on BECN reception (just as GTS) and option to reflect incoming FECNs as BECNs
- Option to enable adaptive shaping which responds to interface congestion (non-empty interface queue)