Figure: L2oGRE MTUs shows an example of plain Layer 3 termination with MTUs.
Figure: L2oGRE MTUs
In this example:
Communication occurs between points 1 and 5.
There may be a router present at point 2. A router at point 2 would see the SR OS node as Layer 3 next-hop.
The device in point 3 encapsulates Layer 2 Ethernet frames into GRE and sends them to the SR OS node.
The SR OS node at point 4 de-encapsulates the packet and performs an Layer 3 lookup on the inner packet to deliver it to the destination.
The following is an example where PW SAP is configured under a Layer 3 interface with a PW carrying IP over Ethernet:
configure
service vprn 1 customer 1 create
interface example-if
address 192.168.1.1/24
sap pw-1:5.5 create
ingress
filter ip 1000
egress
filter ip 2000