Hello Maria,
Lets take it like bellow:-
a)L3 From the prespective of the Provider:
1-Its easier to provision.
2-No need for full mesh point to point links.
3- Security breaks are likely to be occured.
4- Added overhead (Additional administrative confi overhead).
5- reduces cost.
6- Security precaution has to be taken int account.
B) L3From the prespective of the Customer:
1) Requires specific hardware and memory.
2) requires the customer to participate in L3 routing.
3) Customer dont usually like to implementit due to Security reasons.
4) Securing their Network at layer2 and layer-3 is required for Sensitive applications belongs to certain Organization.
5) Administrative Overhead.
C)L2 From the Prespective Of the Provider:
1) Doesnt require the Provider to participate in the customer Network.
2) lesser administrative Overhead than L3-VPN.
3) requires full mesh of L2-VPN point to point if multiple sites involved.
4) Not easier to provision if Controlling traffic between sites required like (Hub and Spoke),(Centeral Services), (Overlapping).
5) If multiple Sites involved , Cost wise increases.
6) Better Security Control than L3.
d)L2 From th prespective of the Customer:
1) More Secured.
2) Lesser administrative Overhead than L3
3) The requirement of Special Hardware/Memory is minimized.
4) If Multiple Sites involved, Multiple L2VPN dedicated Point to point required.
5) Therfore, additional cost takes place if (4) is applicable.
The Conclusion: It really varies and depends of the requirment. If for example its a point to point link , I would go for a point to point L2VPN. If its more than 2 sites requires full mesh, then L2VPN is also applicable.
IF better control of traffic or partial mesh required for more than 2 sites, then L3-VPN is most appropriate solution.
HTH
Mohamed
