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Ethernet over Soft
Generic Routing Encapsulation (EoGRE) is an aggregation solution for
aggregating WiFi traffic from hotspots. This solution enables customer premises
equipment (CPE) devices to bridge the Ethernet traffic from an end host, and
encapsulates the traffic in Ethernet packets over an IP GRE tunnel. The IP GRE
tunnel terminates on a service provider broadband network gateway, which then
terminates the end host traffic and manages the subscriber session for the end
host.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information,
see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module,
and to see a list of the releases in which each feature is supported, see the feature information table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature
Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Restrictions for
Layer 2 Ethernet over GRE
Transport on
IPv6 is not supported.
Virtual
Ethernet interface does not support encapsulation untagged.
L2 EoGRE is not
supported on the Cisco CSR1000V platform.
Multicast
traffic is not supported.
Information About
Layer 2 Ethernet over GRE
The ASR 1000
platform services as the SP broadband network gateway which:
Terminates the IP GRE tunnel, and/or
Manages the subscriber session for the end-host client.
Figure 1. Ethernet over Soft GRE Deployment
The deployment model that is supported is the two-box model:
In the two-box model, the ASR 1000 router provides only the
functionality to terminate the bridged Ethernet over soft GRE traffic. The ISG
subscriber management resides in an external router which is connected with the
router using L2 bridge-domain.
The major components involved in L2 EoGRE are:
Virtual Ethernet interface.
Ethernet service instance.
IP GRE tunnel data plane.
L2 bridge-domain data plane.
Control Plane—After the Virtual Ethernet interface is configured,
the Virtual Ethernet interface is downloaded to the ASR 1000 platform as a
virtual interface.
Service instances (EVCs) are configured under the virtual ethernet
interface and are downloaded to ASR1K platform. The service instances are then
propagated in the ASR 1000 platform to fman-rp, fman-fp, cpp-client and cpp
dataplane, where the EVC feature invocation arrays (FIAs) are enabled.
Data Plane—When receiving the IP GRE encapsulated Ethernet
packet, the data plane tunnel ingress processing checks the protocol field in
the GRE header. If the protocol is transparent Ethernet bridging protocol
(0x6558), the packet is identified as Ethernet over soft GRE packet and is
directed to the Ethernet service instance classification module. The Ethernet
service instance classification module classifies the packet into the service
instance configured under the Virtual Ethernet interface using the VLAN tag in
the packet. After the Ethernet service instance is identified, the packet goes
through the programmed processing FIA under the Ethernet service instance such
as vlan tag manipulation and is then sent to L2 bridge domain for further
processing. At the L2 bridge domain processing module, the client source MAC
address is dynamically learned, and so is the IP GRE tunnel end-points. As a
result, the MAC address table contains the IP GRE tunnel end-points for the
client MAC address.
The packet is then either bridged to the external ISG for subscriber
processing in the case of the two-box deployment model. In the direction where
the ISG, either external or internal, sends a packet to the mobile client, the
L2 bridge domain looks up the destination MAC address using the L2 bridge
domain MAC address table. Once the result is found, the IP GRE tunnel end point
addresses are also retrieved from the MAC address table. The L2 Ethernet packet
is then encapsulated into the IP GRE tunnel using the retrieved tunnel end
point address. Once encapsulated into the IP GRE packet, IP lookup is then
performed and the packet is sent to the CPE.
Configuration Example:
Two-box Deployment Model
service instance 1 ethernet
encap dot1q 100
rewrite ingress tag pop 1 symmetric
bridge-domain 10
Interface Gi1/0/0
service instance 1 ethernet
encap dot1q 100
rewrite ingress tag pop 1 symmetric
bridge-domain 10
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The following table provides release information about the feature or features described in this module. This table lists
only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise,
subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco
Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 1. Feature Information for
Layer 2 Ethernet over GRE
Feature
Name
Releases
Feature
Information
Layer 2
Ethernet over GRE
Cisco IOS XE Release 3.9S
Ethernet
over Soft Generic Routing Encapsulation (EoGRE) is an aggregation solution for
aggregating WiFi traffic from hotspots. This solution enables customer premises
equipment (CPE) devices to bridge the Ethernet traffic from an end host, and
encapsulates the traffic in Ethernet packets over an IP GRE tunnel. The IP GRE
tunnel terminates on a service provider broadband network gateway, which then
terminates the end host traffic and manages the subscriber session for the end
host.
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