VPN-MPLS on 3600

[afahmi]

Should we increase MTU of Packet if we deploy VPN on MPLS network on Cisco 3600 series configures as PE-to-PE, above 1500 bytes due to additional tag on IP header ????

[wukunpeng]

When your 3600 use HSSI or ATM oc-3,you can make the MTU=4470,another interface only MTU=1500.

[Bellman]

I am puzzled of the infomation about the paltform of PE routres in MPLS VPNs.Some articles on Cisco's Web site says only the routes above Cisco 3600 series can be used as PE router in MPLS VPNs,and some says Cisco 2600 Series routers can be used in this circumstance. Would you like tell me which is right?Thanks a lot.