Enterprise QoS Solution Reference Network Design Guide

Chapter 3 WAN Aggregator QoS Design
Version 3.3
Figure 3-11 Medium-Speed Frame Relay Links
WAN Aggregator
WAN Edge Link-Specific QoS Design
Note In some cases, however, administrators have chosen to enable FRF.12 on T1/E1 speed links, even though
the fragment size for a 10-ms maximum serialization delay at such speeds is greater than the MTU of
Ethernet (1500 bytes). The rationale behind doing so is to retain the Frame Relay dual-FIFO queuing
mechanism at Layer 2, which can provide slightly superior service levels under certain conditions.
Generally, this is not required however.
Example 3-19 Medium-Speed (T1/E1) Frame Relay QoS Design Example
!
policy-map MQC-FRTS-1536
class class-default
shape average 1460000 14600 0 ! Enables MQC-Based FRTS
service-policy WAN-EDGE ! Queues packets headed to the shaper
!
…
!
interface Serial2/0
no ip address
encapsulation frame-relay
!
interface Serial2/0.12 point-to-point
ip address 10.1.121.1 255.255.255.252
description 1536kbps FR Circuit to RBR-3745-Left
frame-relay interface-dlci 102
class FR-MAP-CLASS-1536 ! Binds the map-class to the FR DLCI
!
…
!
map-class frame-relay FR-MAP-CLASS-1536
service-policy output MQC-FRTS-1536 ! Attaches nested MQC policies to map-class
!
Verification commands:
show policy map
show policy-map interface
Frame Relay Link
T1/E1
Frame Relay
Cloud
High-Speed (Multiple T1/E1 and Greater) Frame Relay Links
Branch Router
Recommendation: Use IP CEF per-packet load balancing for load sharing across multiple physical
Frame Relay links.
When multiple Frame Relay circuits exist between a central WAN aggregation router and a remote
branch router, as illustrated in Figure 3-12, it is recommended that IP CEF per-packet load balancing be
used to load-share between the links. Multilink PPP over Frame Relay (MLPoFR) bundles are complex
Enterprise QoS Solution Reference Network Design Guide
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