Active Nodes
Active routers: HUB-EC-1, HUB-EC-2, SPK-EC-1, SPK-EC-2, SPK-EC-3, EDGE-3
Key Concepts
QoS on DMVPN Tunnels
QoS policies applied to a physical WAN interface are not automatically inherited by the mGRE tunnel interface. The service-policy must be applied directly to Tunnel0. DSCP markings are preserved inside GRE encapsulation — the outer IP header should be marked using set ip dscp in the class-map to ensure proper treatment by ISP QoS. LLQ (Low Latency Queuing) via the priority keyword provides strict priority for voice (DSCP EF), preventing delay even under congestion.
CBWFQ Bandwidth Allocation
Class-Based Weighted Fair Queuing allocates minimum guaranteed bandwidth to each class. The bandwidth statement reserves capacity as either absolute kbps or a percentage of interface rate. Remaining bandwidth (after priority and bandwidth statements) goes to the default class using fair-queue. On DMVPN spokes with sub-rate uplinks, traffic shaping (shape average) on the physical interface feeds into the CBWFQ queues correctly — without shaping, bursts cause tail-drop before QoS policies engage.
EIGRP Bandwidth/Delay Tuning
EIGRP named mode uses "wide metrics" (64-bit) that eliminate the metric ceiling problem with high-speed interfaces. On DMVPN, adjusting bandwidth and delay on Tunnel0 controls EIGRP metric and thus path selection. Set bandwidth to match the actual sub-rate WAN link capacity — otherwise EIGRP underestimates the cost and may select an inferior path. The delay parameter fine-tunes preference between paths with similar bandwidth.
QoS Configuration on SPK-EC-1
class-map match-all VOICE-TRAFFIC match dscp ef class-map match-all VIDEO-TRAFFIC match dscp af41 class-map match-all CRITICAL-DATA match dscp af31 policy-map DMVPN-QOS-OUT class VOICE-TRAFFIC priority 512 class VIDEO-TRAFFIC bandwidth 1024 class CRITICAL-DATA bandwidth 512 class class-default fair-queue interface Tunnel0 bandwidth 10000 delay 1000 service-policy output DMVPN-QOS-OUT