Hierarchical VPLS QoS
Hierarchical VPLS (H-VPLS) is an extension of basic VPLS to provide scaling and operational benefits. H-VPLS partitions a network into several edge domains that are interconnected using an MPLS core. H-VPLS provides a solution to deliver Ethernet multipoint services over MPLS. The use of Ethernet switches at the edge offers significant technical and economic advantages. H-VPLS also allows Ethernet point-to-point and multipoint Layer 2 VPN services, as well as Ethernet access to high-speed Internet and IP VPN services.
Note |
The Cisco CRS Series Modular Services Card 140G (CRS-MSC-140G) does not support Hierarchical VPLS QoS. |
Hierarchical VPLS with Pseudowire Access
This figure shows the pseudowire (PW) access for H-VPLS. The edge domain can be an MPLS access network. In an H-VPLS configuration, the N-PE router forwards L2VPN packets from an Access PW to a Core PW and also forwards packets from a Core PW to an Access PW.
When forwarding packets, the N-PE router removes the virtual circuit (VC) label and also adds a VC label. The set mpls experimental topmost command, the set mpls experimental imposition command, or both of these commands can be applied to a QoS policy in a PW <-> PW configuration. Standard VPLS QoS actions, such as match vlan inner , match cos inner , and set cos inner , apply to H-VPLS QoS as well.
This table summarizes the actions taken with respect to the MPLS experimental value in a PW<-> PW configuration.
Ingress/Egress |
||
---|---|---|
Default |
Ingress Egress |
MPLS experimental value from the VC is copied to all imposed labels |
set mpls experimental topmost |
Ingress |
MPLS experimental value from the QoS policy is copied to all imposed labels |
set mpls experimental topmost |
Egress |
MPLS experimental value from the QoS policy is copied to the outermost labels |
set mpls experimental imposition |
Ingress |
MPLS experimental value from the QoS policy is copied to all imposed labels |
set mpls experimental topmost and set mpls experimental imposition |
Ingress |
MPLS experimental value from the set mpls experimental imposition command in the QoS policy is copied to all imposed labels |
Hierarchical VPLS QoS: Example
In this example, the N-PE router forwards L2VPN packets from an Access PW to a Core PW and also forwards packets from a Core PW to an Access PW. The example defines classes and specifies experimental values in the topmost MPLS label as match criteria for a class map to match the MPLS label. A QOS policy is applied to the ingress Core interfaces in the MPLS Access Network or the MPLS Core Network.
In this H-VPLS QoS configuration, the U-PE (customer) router and the N-PE (service provider) router have different QoS policies. The policy on the U-PE router specifies a high experimental value so traffic can receive more bandwidth and is sent as fast as possible to minimize jitter and delay. (topmost values of 4, 5, and 6.)
The N-PE router needs to balance traffic from various sources. The N-PE router remarks the packets by adding a label with a lower experimental value (imposition values of 1 and topmost values of 2).
class-map match-any exp1-top
match mpls experimental topmost 4
end-class-map
!
class-map match-any exp2-top
match mpls experimental topmost 5
end-class-map
!
class-map match-any exp3-top
match mpls experimental topmost 6
end-class-map
policy-map RX-Core
class exp1-top
set mpls experimental imposition 1
shape average percent 20
!
class exp2-top
set mpls experimental imposition 1
set mpls experimental topmost 2
shape average percent 20
class exp3-top
set mpls experimental topmost 2
shape average percent 20
class class-default
set mpls experimental imposition 1
shape average percent 20
!
end-policy-map