VMware NSX

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  • 1.  MTU over WAN question

    Posted Dec 02, 2016 08:52 PM

    Hi,

    I have two data centers. For several reasons, I can't change the MTU on the WAN between them.

    I want to extend my VXLANs over both data centers.

    So :

    1- Am I screwed ?

    2- Can I create a L2-VPN between sites with NSX edges on both end and pass the VXLAN traffic IN the vpn ? If so, I suppose there is fragmentation ?

    3- Can I create a L2-VPN between sites with NSX edges on both end and switch from VXLAN to VLAN when traffic comes out of the first DC, then pass the L2-VPN (vlan based off course) and then switch back to VXLAN at the other end ? Does this works ?

    4- Another solution I didn't think ?

    Thanks !



  • 2.  RE: MTU over WAN question
    Best Answer

    Posted Dec 03, 2016 06:39 PM

    Hi

    L2VPN between sites with both VXLAN or one of them is non-VXLAN are supported since NSX 6.1

    See this link: VMware NSX vSphere 61 Documentation Center - L2VPN Overview

    l2

    l2

    Depends on your traffic, the Edge performing L2VPN would also quite cpu intensive and this would provide up to ~2Gbps througput.

    If you need more throughput e.g. ~10Gbps you will need to do stretch VXLAN which requires change of MTU on the WAN



  • 3.  RE: MTU over WAN question

    Posted Dec 03, 2016 11:19 PM

    That makes a lot of sense

    Thank you very much !



  • 4.  RE: MTU over WAN question

    Posted Dec 04, 2016 04:21 AM

    Just to add to it, even for the L2 VPN the MTU size needs to be set to 1600.

    Attached is the reference from the VCP6-NV book regarding this.



  • 5.  RE: MTU over WAN question

    Posted Dec 04, 2016 01:31 PM

    oh !

    so there is no way to extend network without a 1600 MTU wan then ??



  • 6.  RE: MTU over WAN question

    Posted Dec 04, 2016 02:53 PM

    I just found this in the NSX reference design guide

    So, which one is true ?



  • 7.  RE: MTU over WAN question

    Posted Dec 05, 2016 03:41 AM

    i believe the NSX reference design guide is right. There is no requirement of the VXLAN extension across DC for the L2 VPN

    MTU is not required to be more than 1500



  • 8.  RE: MTU over WAN question

    Posted Dec 15, 2016 07:18 AM

    Both VMware® NSX for vSphere Network Virtualization Design Guide ver 3.0 and NSX-V Multi-site Options and Cross-VC NSX Design Guide‌ says L2VPN should work in 1500 MTU. I have some L2VPN deployment running on default MTU 1500 and they are working fine.