Layer 2 control protocols

SR OS has awareness of multiple Layer 2 Control Protocols (L2CP). In some configurations, these L2CP frames are extracted and processed by the receiving SR. However, there are some deployments where it is useful to have the SR transparently forward the L2CP frames through a Layer 2 VLL or VPLS service. The SR OS support for transparent tunneling is configured on a protocol basis, as described in this section.

L2CP frames are processed as follows:

tunneled

SR OS passes the frames through any associated service.
peered

SR OS extracts and processes the frame.
discarded

SR OS extracts the frame and then discards it.

The following L2CP frames are always tunneled:

STP/RSTP/MSTP (assuming Spanning Tree is not enabled if the ingress SAP is attached to a VPLS service).

These frames are identified as frames with a destination MAC address of 01:80:C2:00:00:00.
LAMP

These frames are identified as frames with a destination MAC address of 01:80:C2:00:00:02, Ethertype (0x8809), and slow-protocol subtype 0x02.
MAC specific control protocols

These frames are identified as frames with a destination MAC address of 01:80:C2:00:00:04.
provider bridge group address 01:80:C2:00:00:08
provider bridge MVRP address 01:80:C2:00:00:0D

Other frame types are processed according to the CLI configuration, as follows:

PAUSE frames

PAUSE frames are transmitted to request backward direction flow control. By default, SR OS peers pause frames on reception and pause the transmit side of the port. On some ports, this behavior can be changed to discard PAUSE frames. For applicable ports, use the following command to discard PAUSE frames:
- MD-CLI
```
configure port ethernet discard-rx-pause-frames true
```
- classic CLI
```
configure port ethernet discard-rx-pause-frames
```
PAUSE frames are never tunneled.

PAUSE frames are identified as frames with a destination MAC address of 01:80:C2:00:00:01, Ethertype (0x8808), and subtype 0x0001.
LACP frames

If the port is part of a LAG, the LACP frames are peered. If the port is not part of a LAG, the LACP frames are discarded or tunneled based on the configuration of the following command.
```
configure port ethernet lacp-tunnel
```
LACP frames are identified as frames with a destination MAC address of 01:80:C2:00:00:02, Ethertype (0x8809), and the slow-protocol subtype (0x01).
EFM-OAM frames

If the port has EFM-OAM processing enabled, the EFM-OAM frames are peered. If EFM-OAM processing is not enabled on the port, the EFM-OAM frames are discarded or tunneled based on the configuration of the following command.
```
configure port ethernet efm-oam tunneling
```
EFM-OAM frames are identified as frames with a destination MAC address of 01:80:C2:00:00:02, Ethertype (0x8809), and the slow-protocol sub-type (0x03).
ESMC frames

If the port is an input reference to the central frequency clock, the ESMC frames are peered. If the port is not an input reference to the central frequency clock, the ESMC frames are discarded. Use the following command to override the preceding scenarios and tunnel the ESMC frames:
- MD-CLI
```
configure port ethernet ssm esmc-tunnel true
```
- classic CLI
```
configure port ethernet ssm esmc-tunnel
```
ESMC frames are identified as frames with a destination MAC address of 01:80:C2:00:00:02, Ethertype (0x8809), and the slow-protocol sub-type (0x0A).
802.1x frames

By default, the 802.1x frames are extracted when they are received. For extracted frames, if a RADIUS server is configured, the frames are peered; otherwise, they are discarded. Use the following command to override the extraction and tunnel the 802.1x frames:
- MD-CLI
```
configure port ethernet dot1x tunneling true
```
- classic CLI
```
configure port ethernet dot1x tunneling
```
802.1x frames are identified as frames with a destination MAC address of 01:80:C2:00:00:03, and Ethertype (0x888E).
E-LMI frames

If Ethernet Local Management Interface (E-LMI) processing is enabled on the port, E-LMI frames are peered. Otherwise, the E-LMI frames are dropped from VPLS and tunneled for Epipe.

E-LMI frames from VPLS are tunneled when the following is the case:
- the following command is included in the service
```
configure service vpls tunnel-elmi
```
- the following command is not enabled on the port
```
configure port ethernet elmi
```
- the encapsulation of the E-LMI frame matches the VPLS service tagging
E-LMI frames are identified as frames with a destination MAC address of 01:80:C2:00:00:07, and Ethertype (0x88EE).
LLDP frames

If LLDP processing is enabled on the port, LLDP frames are peered. Otherwise, LLDP frames are discarded or tunneled based on the configuration of the following command.
```
configure port ethernet lldp dest-mac tunnel-nearest-bridge
```
LLDP frames are identified as frames with a destination MAC address of 01:80:C2:00:00:0E, and Ethertype (0x88CC).
PTP peer delay frames

If the port is configured in the router as an active port within the PTP process, the frames are peered; otherwise, the frames are tunneled.

PTP message frames are identified as frames with destination MAC address 01:80:C2:00:00:0E, and Ethertype (0x88F7).

Note: E-LMI must be disabled and the port must not be configured as a PTP port.

Configure the following commands on the port to achieve the maximum transparency of L2CP frames:

MD-CLI

configure port ethernet discard-rx-pause-frames true
configure port ethernet lacp-tunnel true
configure port ethernet efm-oam tunneling true
configure port ethernet ssm esmc-tunnel true
configure port ethernet dot1x tunneling true
configure port ethernet lldp dest-mac tunnel-nearest-bridge true

classic CLI

configure port ethernet discard-rx-pause-frames
configure port ethernet lacp-tunnel
configure port ethernet efm-oam tunneling
configure port ethernet ssm esmc-tunnel
configure port ethernet dot1x tunneling
configure port ethernet lldp dest-mac tunnel-nearest-bridge