Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 552)

Tunnel LSP configured COS or
VLL configured COS or
802.1q priority or
Configured port priority Value placed in the tunnel and
VC label EXP field Priority queue
7 7 qosp7 (highest priority)
6 6 qosp6
5 5 qosp5
4 4 qosp4
3 3 qosp3
2 2 qosp2
1 1 qosp1
0 0 qosp0 (best effort)
528 Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide
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How MPLS VLL works
4
QoS for VLL traffic at transit LSRs
At each transit LSR, the device reads the value in the tunnel label’s EXP field and places the
incoming EXP value in the EXP field of the outbound packet. The outbound MPLS packet is
assigned to one of the eight priority queues based on the value in the EXP field. The EXP bits in the
MPLS header are used to assign the packet to a priority queue as follows:
EXP Bits in tunnel label Priority queue
7 qosp7 (highest priority)
6 qosp6
5 qosp5
4 qosp4
3 qosp3
2 qosp2
1 qosp1
0 qosp0 (best effort)
QoS for VLL traffic at the penultimate LSR
When the packet reaches the penultimate LSR in the LSP, its tunnel label is popped, leaving the VC
label. The MPLS packet is placed in one of the priority queues using the value in the EXP field of the
VC label. Since the VC label has the same EXP value as the tunnel label, the packet is placed in the
same queue used for the tunnel LSP.
QoS for VLL traffic at the egress LER
At the VLL endpoint, the VC label is popped and the packet is forwarded as a Layer 2 packet. The
packet is placed in one of the priority queues based on the contents of the EXP field in the VC label,
as follows: