CoS Support on EVPN VXLANs
You can configure class of service (CoS) features on VXLAN interfaces. VXLAN traffic from different tenants traverses network boundaries over the same physical underlay network. To ensure fairness in the treatment of traffic for all tenants in the VXLAN, and to prioritize higher priority traffic, apply CoS features to the VXLAN interfaces.
Understanding CoS on VXLAN Interfaces
This section describes how classification and rewrite rules are applied to packets in a VXLAN instance. Figure 1 shows a simple VXLAN with two leaf nodes and one spine node.
Refer to Figure 1 to understand the packet flow with DSCP/ToS fields in a VXLAN:
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CE 1 sends a packet with Layer3 DSCP/ToS bit programmed to the Leaf 1 node.
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Leaf 1 receives the original packet and appends the VXLAN header on top of the original packet. The outer VXLAN Layer3 header uses the original packet DSCP/Tos bit. You can create classifiers based on the original packet DSCP/802.1p bit. The ingress interface on the ingress leaf supports DSCP and 802.1p classifiers.
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If rewrite is configured on Leaf 1, the inner header will have the DSCP/802.1p bit set by CE 1 and the outer header will have the rewrite bit. Only DSCP rewrite rules are supported, except on QFX10000 switches where 802.1p rewrite is also supported if the underlay is tagged.
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The Spine node receives the VXLAN packet and can use ingress classification using these DSCP bits and forward the packet to the egress interface with the appropriate forwarding class.
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The Spine egress interface can rewrite these bits using rewrite rules. These Spine rewrite rules only affects the outer Layer3 DSCP field. The inner/original packet still holds the DSCP/802.1p bit that was set by CE 1.
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Leaf 2 receives the packet, processes the tunnel termination, and remove the outer VXLAN header.
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Leaf 2 classification and rewrite functionality works on the inner header.
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The original packet arrives on CE 2.
On the leaf nodes, if the packet is multicast,
you can use multi-destination
classification to create appropriate multicast
classification and rewrite rules.
Configuring CoS on VXLAN Interfaces
This section shows sample configurations of classifiers and rewrite rules for the leaf and spine nodes in VXLAN using Figure 1 as a reference. You can create schedulers as normal for the classifiers on each node.
Sample configuration of classifiers and rewrite rules on Leaf 1.
Sample configuration of classifiers and rewrite rules on the Spine.
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Create a classifier based on the outer VXLAN DSCP/ToS bits:
[edit class-of-service classifiers] user@spine#set dscp dscp_cf forwarding-class best-effort loss-priority low code-points af22 user@spine#set dscp dscp_cf forwarding-class network-control loss-priority high code-points af31 user@spine#set dscp dscp_cf forwarding-class expedited-forwarding loss-priority low code-points af13 user@spine#set dscp dscp_cf forwarding-class assured-forwarding loss-priority high code-points cs3
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Apply the classier to the ingress Spine interfaces:
[edit class-of-service interfaces] user@spine#set ge-0/0/3 unit 0 classifiers dscp dscp_cf user@spine#set ge-0/0/5 unit 0 classifiers dscp dscp_cf
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Create a rewrite rule for the outer VXLAN DSCP/ToS bits:
[edit class-of-service rewrite-rules] user@spine#set dscp dscp_rw forwarding-class best-effort loss-priority low code-points af22 user@spine#set dscp dscp_rw forwarding-class network-control loss-priority high code-points af31 user@spine#set dscp dscp_rw forwarding-class expedited-forwarding loss-priority low code-points af13 user@spine#set dscp dscp_rw forwarding-class assured-forwarding loss-priority high code-points cs3
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Apply the rewrite rule to the egress Spine interfaces:
[edit class-of-service interfaces] user@spine#set ge-0/0/4 unit 0 rewrite-rules dscp dscp_rw user@spine#set ge-0/0/6 unit 0 rewrite-rules dscp dscp_rw
Sample configuration of classifiers and rewrite rules on Leaf 2.
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Create a classifier based on the original DSCP/ToS bits, as the VXLAN header is removed at tunnel termination before forwarding classes are applied:
[edit class-of-service classifiers] user@leaf2#set dscp dscp_cf forwarding-class best-effort loss-priority low code-points 100000 user@leaf2#set dscp dscp_cf forwarding-class network-control loss-priority high code-points 110000 user@leaf2#set dscp dscp_cf forwarding-class expedited-forwarding loss-priority low code-points 011010 user@leaf2#set dscp dscp_cf forwarding-class assured-forwarding loss-priority high code-points 001010
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Apply the classier to the ingress Leaf 2 interfaces:
[edit class-of-service interfaces] user@leaf2#set ge-0/0/7 unit 0 classifiers dscp dscp_cf user@leaf2#set ge-0/0/8 unit 0 classifiers dscp dscp_cf
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Create a rewrite rule for the original DSCP/ToS bits:
[edit class-of-service rewrite-rules] user@leaf2#set dscp dscp_rw forwarding-class best-effort loss-priority low code-points 100000 user@leaf2#set dscp dscp_rw forwarding-class network-control loss-priority high code-points 110000 user@leaf2#set dscp dscp_rw forwarding-class expedited-forwarding loss-priority low code-points 011010 user@leaf2#set dscp dscp_rw forwarding-class assured-forwarding loss-priority high code-points 001010
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Apply the rewrite rule to the egress Leaf 2 interface:
[edit class-of-service interfaces] user@leaf2#set ge-0/0/9 unit 0 rewrite-rules dscp dscp_rw
To check the CoS configuration on one of the interfaces:
user@node#show class-of-service interface interface-name
To check the queue statistics on one of the interfaces:
user@node#show interfaces queue interface-name
Implementing CoS on VXLAN Interfaces (Junos OS Evolved)
CoS for EVPN VXLAN traffic is supported using a combination of classifiers, schedulers, and rewrite rules. This section describes how these components are implemented across different nodes on devices running Junos OS Evolved to apply CoS on the EVPN VXLAN traffic.
- Classification at User Network Interface (UNI)/Ingress PE — Traffic classification based on IEEE 802.1p and Differentiated Services code point (DSCP) are supported on the ingress PE where the EVPN VXLAN tunnel is initiated. BA and MF classifiers can be applied to Enterprise style (EP) or Service Provider (SP) style access interfaces.
- Classification at Network Node Interface (NNI)/Egress PE — Traffic classification based on IEEE 802.1p and Differentiated Services code point (DSCP) are supported on the egress PE where the EVPN VXLAN tunnel is terminated. BA classifiers can be applied to the underlying logical interface or unit. MF classifiers are not supported in tunnel terminations.
- Rewrite at NNI — After the encapsulation of the VXLAN tunnel, the rewrites on the
outer/tunnel header are configured using the rewrite rules on the underlying
logical interface or unit. Based on the configured rewrite rules, the VXLAN
traffic is classified in the Spine/Network.
DSCP rewrite on the outer/tunnel header of VXLAN packets is supported on the NNI interface.
Rewrite rules are supported in the following EVPN VXLAN scenarios:- Intra-VNI L2 gateway — Rewrite rules are applied to both unicast and broadcast, unknown unicast, and multicast (BUM) traffic.
- Inter-VNI L3 gateway — Centrally-routed bridging (CRB) and edge-routed bridging (ERB).
- EVPN Type 5 routes.
- Rewrite at UNI — After the termination
of the VXLAN tunnel, the rewrites on the inner
headers are configured using rewrite rules on the
Enterprise style (EP) or Service Provider (SP)
style access interfaces. Based on the configured
rewrite rules, the decapsulated packets are
classified in the CE side network. The following
rewrite rules are supported on the UNI interface
for the decapsulated packets:
- DSCP rewrites on the inner IPv4/IPv6 header
- IEEE 802.1p rewrites on the inner Ethernet header (if tagged)
- Intra-VNI L2 gateway — Rewrite rules are applied to both unicast and broadcast, unknown unicast, and multicast (BUM) traffic.
- Inter-VNI L3 gateway — Centrally-routed bridging (CRB) and edge-routed bridging (ERB).
- EVPN Type 5 routes.
- Scheduling — Traffic prioritization and bandwidth reservation are achieved by using schedulers. The schedulers are associated with a forwarding class set via classifiers.
Platform-Specific CoS on EVPN-VxLANs Behavior
Use Feature Explorer to confirm platform and release support for specific features.
Use the following table to review platform-specific behaviors for CoS on EVPN-VxLANS:
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Platform |
Difference |
|---|---|
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PTX Series routers |
The following limitations apply to PTX routers:
Note:
In EVPN-VXLAN networks with an IPv6 underlay, some PTX Series routers support CoS classification and explicit congestion notification (ECN) copy operations, but not PFC, DSCP copy, or IEEE 802.1p rewrite. See Feature Explorer for platform and release support. |
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PTX10002-36QDD routers |
PTX10002-36QDD routers that originate or terminate EVPN-VXLAN tunnels and have ECN enabled automatically copy the ECN bits from the inner header to the outer header. The router copies the ECN bits from the outer header to the inner header if the inner header has the ECT bit set. If the router experiences congestion, it sets the CE bits if the ECT bit is enabled. These routers support ECN copy operations in EVPN-VXLAN networks with an IPv4 underlay or an IPv6 underlay. |
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QFX5130 and QFX5700 switches |
The following limitations apply to the QFX5130 and QFX5700 platforms:
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QFX10000 Series switches |
The following limitation applies to QFX10000 platforms:
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