Cisco ASR 920 series Configuration Guide Ethernet Router

X, Site 1, will build a spanning tree on the switches at that site without considering convergence parameters
based on Customer X's switch in Site 2. This could result in the topology shown in figure below.
Figure 1: Layer 2 Protocol Tunneling
Figure 2: Layer 2 Network Topology without Proper Convergence
In a service-provider network, you can use Layer 2 protocol tunneling to enhance the creation of EtherChannels
by emulating a point-to-point network topology. When you enable protocol tunneling (PAgP or LACP) on
the service-provider switch, remote customer switches receive the PDUs and can negotiate the automatic
creation of EtherChannels.
Carrier Ethernet Configuration Guide (Cisco ASR 920 Series)
36
Ethernet Virtual Connections Configuration
Configuring IEEE 802.1Q Tunneling and Layer 2 Protocol Tunneling Using EFPs

Cisco ASR 920 series Specifications

General

Form Factor	1RU
Operating System	Cisco IOS XE
Model	ASR 920 series
Memory	4 GB DRAM
Power Supply	AC or DC
Storage Temperature	-40°C to 70°C (-40°F to 158°F)
Relative Humidity	5% to 95% non-condensing
MTBF	Varies by model
Management	CLI, SNMP