Layer 2 Mode

Ethernet frames can be forwarded from one LAN segment or VLAN to another by bridging or switching functions on Juniper Networks devices. Bridging and switching functions are performed in Layer 2 of the OSI reference model—the Data Link Layer. Though the terms bridging and switching are often used interchangeably, switching functions are typically performed in hardware in application-specific integrated circuits (ASICs) while bridging functions are usually performed in software.

Table 25 lists the Layer 2 features that are supported on SRX Series and J Series devices. For more information about Layer 2 features, see the Junos OS Layer 2 Bridging and Switching Configuration Guide for Security Devices.

Table 25: Layer 2 Mode Support

Feature	SRX100 SRX210 SRX240	SRX650	SRX3400 SRX3600 SRX5600 SRX5800	J Series
802.1x port-based network authentication	Yes	Yes	No	Yes
Flexible Ethernet services	Yes	Yes	No	Yes
Generic VLAN registration protocol	Yes	Yes	No	Yes
IGMP snooping	Yes	Yes	No	Yes
Integrated routing and bridging (IRB) interface	Yes	Yes	Yes*	Yes
Integrated routing and bridging (IRB)	Yes	Yes	No*	Yes
Link Layer Discovery Protocol (LLDP) and Link Layer Discovery Protocol—Media Endpoint Discovery (LLDP-MED)	Yes	Yes	No	Yes
Q-in-Q tunneling	SRX210 and SRX240 only	Yes	No	Yes
Spanning Tree protocols	Yes	Yes	Yes	Yes
VLAN retagging	No	No	Yes	No
VLANs	Yes	Yes	Yes	Yes

* On SRX3400, SRX3600, SRX5600, and SRX5800 devices, we support an IRB interface where you can terminate management connections in transparent mode. However, you cannot route traffic on that interface or terminate IPsec VPNs.