Ima Bum
asked on
Layer 2
Hi All,
I know this may seem like a lame question and I sort of understand it, but I'm trying to get a "better" if you will --- understanding of L2 links across WANs and MANs.
Frame Relay seems like an obvious example but it still uses L3 (right) so in today's networks using metro-Ethernet and fiber I'm looking for some clearer examples (explanations) and trying to better understand what the glue is that bonds L2 over WAN links. Sure I can Google all day but I just keep seeing examples of what L2 does and what L3 does and not how L2 links across WAN links actually work.
Thanks,
R
I know this may seem like a lame question and I sort of understand it, but I'm trying to get a "better" if you will --- understanding of L2 links across WANs and MANs.
Frame Relay seems like an obvious example but it still uses L3 (right) so in today's networks using metro-Ethernet and fiber I'm looking for some clearer examples (explanations) and trying to better understand what the glue is that bonds L2 over WAN links. Sure I can Google all day but I just keep seeing examples of what L2 does and what L3 does and not how L2 links across WAN links actually work.
Thanks,
R
ASKER
Thanks.
I understand what the layers do 1 - 7 but I seem to missing something that's right in front of me.
Router 1 IP : 192.168.1.1/252
Router 2 IP: 192.168.1.2/252
Router one is in Building 1 and Router 2 is in building 2 10 miles away over a fiber, long haul link. So when they call this a layer 2 link, it's actually glued together via L3 but it's probably trunked so it can carry multiple VLANS, right? I'm still learning so appreciated the clarification. I think I understand it now? But really it's not able to carry data until you configure L3?
I understand what the layers do 1 - 7 but I seem to missing something that's right in front of me.
Router 1 IP : 192.168.1.1/252
Router 2 IP: 192.168.1.2/252
Router one is in Building 1 and Router 2 is in building 2 10 miles away over a fiber, long haul link. So when they call this a layer 2 link, it's actually glued together via L3 but it's probably trunked so it can carry multiple VLANS, right? I'm still learning so appreciated the clarification. I think I understand it now? But really it's not able to carry data until you configure L3?
Actually its glued with layer 2. All traffic from router 2 to router1 will occur via mac address. Assuming the fiber comes into a media converter and comes out as an etherent cable, you could unplug the ethernet from the routers on both ends and connect to a switch at either end and bridge the network just like connecting 2 local switches together.
Layer 2 connectivity is exactly a network bridge
Layer 2 connectivity is exactly a network bridge
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ASKER
Thank you for explaining, much appreciated!
On Layer 2 connnections like frame relay, and fiber an ethernet frame enters one end of the connection and exits the other in its original form. With a layer 2 connection, both sides of the connection can share the same ip subnet, but typically you will employ a router at both sides of the connection to provide segmentation and routing capabilities.
Layer 2 is the datalink (ethernet / mac address layer). Devices communicate over layer 2 via mac address. Layer 3 communication occurs via ip, then down to layer 2 mac after it reaches the correct destination subnet.