Reddit reviews Introduction to Carrier Ethernet: A foundation for MEF-CECP training

hello, let me try to break this down:

ELINE/ELAN/ETREE/EACCESS are the generic names of each type of service of which the handoff type determines if its port based (PL) or vlan based (VPL) that maps to the EVC/OVC.

• ELINE = pseudowire/VPWS. this is simply frame in at the uni = frame out at the other uni. if the customer wishes for an untagged handoff (802.3) then its an EPL (port based), if the customer wants an tagged handoff (802.1q) then its an EVPL (vlan based).
  
  
• ELAN = VPLS. this is the "simulation of a switch" in the SP cloud. can be either port based or vlan based.
  
  
• ETREE = H-VPLS or hub and spoke. this would look more like an legacy frame relay network with a hub and a spoke. can be either port based or vlan based.
  
  
• EACCESS = tag manipulation, one side is untagged and one side is tagged OR tags on both sides do not match. you will commonly see this term thrown around with NNI's (E-NNI) and type-2 providers as sometimes we cant match tags up with each other.
  
  
• NNI = these are often done a million different ways BUT think of inter-as option A and instead of different VRF's and PE-CE routing protocols think of a dot1q trunk between 2 SP's where you can do tag manipulation if you choose/need.
  
  next, what is an EVC/OVC:
  
  
• EVC = the circuit within the SP cloud, EVC implies that the circuit starts and ends under the same admin control.
  
  
• OVC = the circuit that takes at least two SP's, this in the real world is called type-2/NNI. this is where it costs me more to build out my last mile to you so i go to an existing SP in the market who has already built to your prem and work a deal out where the circuit starts at the UNI on my network, crosses our NNI and then goes to the UNI on the other SP's network. i will normally place a NID at the offnet location and run CFM/Y.1731 to ensure SLA's are met (same for an EVC). OVC's are defined as each SP's domain of control.
  
  next, management frames:
  
  
• there are a large number of layer 2 frames that depending on the service sold and the hand off (port vs vlan) you can either tunnel, peer or discard. these frames are things like STP BPDU's, DTP, CDP, LLDP, LACP, PAGP, etc. depending on your security practices, what your gear can do and what the customer wants determines how you will handle these.
  
  one last major rule of these type of services is that split horizon is ON (it can be disabled) but a mpls frame that comes in from a pseudowire can not go back out a pseudowire, very important. if you disable these improperly you CAN and WILL start a broadcast storm in your network.
  
  where this shit gets really muddy is where cisco and ciena and juniper and alu(nokia) and MEF start to try and blend stuff, ie cisco has the idea of an UNI/EMI/NNI and then the S-UNI/C-UNI. For ETREE (H-VPLS) they bring in the idea of U-PE and N-PE as well. other vendors have little things like this but of course they have slightly different terminology.
  
  the reason for all the mess is pre MEF becoming the golden standard each vendor kinda did what they wanted, now that MPLS METRO/AToM/etc services have become huge all vendors adopted the MEF terms/standards (MEF 2.0). a book i picked up a few years ago when i started working in an SP really helped me clarify: https://www.amazon.com/Introduction-Carrier-Ethernet-foundation-MEF-CECP/dp/1519117566/ref=sr_1_fkmr0_1?ie=UTF8&qid=1483626522&sr=8-1-fkmr0&keywords=fujitsu+mef+introduction