L2 broadcasts over L2 wan point to point links

[hmc250000]

Site A L2 trunk --- WAN point to point ---L2 trunk SiteB --WAN point to point ---L2 trunk siteC

If we have 3 sites connected A to B (point to point) and B to C (also point to point). 

In a scenario like this will site A be able to reach site C through B and back? Will L2 broadcasts work?

[chrihussey · Accepted solution]

Hello, 

In the simplest terms, if it is L2 all the way through it should work.

Regards

[Mark Malone · Accepted solution]

hi
layer 2 broadcasts stay within a layer 2 broadcast domain , so if the point - point is on another subnet from the original source that sent the broadcast it may not pass

From Juniper doc for info
In a Layer 2 network, broadcasting refers to sending traffic to all nodes on a network.

Layer 2 broadcast traffic stays within a local area network (LAN) boundary; known as the broadcast domain. Layer 2 broadcast traffic is sent to the broadcast domain using a MAC address of FF:FF:FF:FF:FF:FF. Every device in the broadcast domain recognizes this MAC address and passes the broadcast traffic on to other devices in the broadcast domain, if applicable. Broadcasting can be compared to unicasting (sending traffic to a single node) or multicasting (delivering traffic to a group of nodes simultaneously).

Layer 3 broadcast traffic, however, is sent to all devices in a network using a broadcast network address. For example, if your network address is 10.0.0.0, the broadcast network address is 10.255.255.255. In this case, only devices that belong to the 10.0.0.0 network receive the Layer 3 broadcast traffic. Devices that do not belong to this network drop the traffic.

[hmc250000]

Perfect, exactly what I need!