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We have to allow Jumbo frame (MTU 1510) through L2 VPN as well as L3VPN.

Publication Date:  2012-07-27 Views:  160 Downloads:  0
Issue Description
We have to pass 1500 MTU data packet through L2VPN. But maximum we received was 1456
Alarm Information
No alarm Information
Handling Process
  1. We configured VPLS between NE40 to NE40, VPLS UP . But Maximum MTU was 1456
  2. We talked to ISP provide for increase MTU in Transmission Switch .After that our L3 VPN MTU 8000 pass But problem remains for L2 VPN. As L3 VPN have only small length(Around 12 Byte)as compared to L2 VPN header.
  3. After all network equipment configuration analysis which are between our NE40 we find out one switch have maximum MTU 1500 which is connected in L2VPN path . As we require around 1548 mtu to transfer 1500 mtu data.

Root Cause
1 As per customer requirement some Database packets have size upto 1510 and they don’t want fragmentation on Packet. They require Passing this packet from VPLS.
2 Maximum MTU pass through our VPLS was 1456 as remaining byte uses for Vlan header VPLS header and MPLS header.
3. We also change our MTU size up to 9000 in VSI configuration.
4. We require to trasmit 1500 MTU data through L2 VPN
When You face Maximum MTU size issue on VPLS first talked with ISP for Increase MTU size on their elements. Then analyse  and increase MTU Size on all intermediate elements. Also consider some byte used in L2 VPN for MPLS header, VSI ,VLAN using(Depend Upon Tagged/Untagged configuration around 46 Byte -48 byte additionaly will need )