Qinq Mode - Cisco CRS Configuration Manual

Implementing Point to Point Layer 2 services
The following figure illustrates MPLS over Inter-AS with a basic double AS topology with iBGP/LDP in
each AS.
Figure 5: EoMPLS over Inter-AS: Basic Double AS Topology

QinQ Mode

QinQ is an extension of 802.1Q for specifying multiple 802.1Q tags (IEEE 802.1QinQ VLAN Tag stacking).
Layer 3 VPN service termination and L2VPN service transport are enabled over QinQ sub-interfaces.
The Cisco CRS Routers implement the Layer 2 tunneling or Layer 3 forwarding depending on the subinterface
configuration at provider edge routers. This function only supports up to two QinQ tags on the SPA and fixed
PLIM:
• Layer 2 QinQ VLANs in L2VPN attachment circuit: QinQ L2VPN attachment circuits are configured
under the Layer 2 transport subinterfaces for point-to-point EoMPLS based cross-connects using both
virtual circuit type 4 and type 5 pseudowires and point-to-point local-switching-based cross-connects
including full interworking support of QinQ with 802.1q VLANs and port mode.
• Layer 3 QinQ VLANs: Used as a Layer 3 termination point, both VLANs are removed at the ingress
provider edge and added back at the remote provider edge as the frame is forwarded.
Layer 3 services over QinQ include:
• IPv4 unicast and multicast
• IPv6 unicast and multicast
• MPLS
• Connectionless Network Service (CLNS) for use by Intermediate System-to-Intermediate System (IS-IS)
Protocol
Note The Cisco CRS-1 router does not support: bundle attachment circuits and Hot Standby Router Protocol
(HSRP) or Virtual Router Redundancy Protocol (VRRP) on QinQ subinterfaces.
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
Ethernet over MPLS
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