Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-zero checksums
Joe Touch <touch@isi.edu> Fri, 02 May 2014 22:26 UTC
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Date: Fri, 02 May 2014 15:25:10 -0700
From: Joe Touch <touch@isi.edu>
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Subject: Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-zero checksums
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On 5/2/2014 2:34 PM, Tom Herbert wrote: ... > VXLAN draft also breaks this by making accepting packets with > zero checksums a MUST. > > That's not "breaking" anything; VXLAN is - to UDP - an application. > > Perhaps not, but making it a MUST in the encapsulation protocol > definition to always accept UDP packets with zero checksums seems a bit > austere. For instance, if I know within my deployment that all senders > are configured to use checksums, then receiving a packet with zero > checksum should be considered an invalid packet. Sorry if I'm missing something here - this started with the following, from draft-mahalingam-dutt-dcops-vxlan-09, which focuses on the non-zero checksum case: "When a decapsulating endpoint receives a packet with a non-zero checksum it MAY choose to verify the checksum" The point is that this is NOT an option. If the UDP checksum is nonzero, it MUST be validated. (this isn't open to interpretation; if you want to have VXLAN accept non-zero checksums that are invalid, then you are not compliant with what few standards the Internet has) --- When the UDP checksum is zero, RFC1122 says that: - an app MAY optionally be able to configure a system to accept zero-checksum UDP packets up or discard them It would be a bad idea for VXLAN to assume that this configuration is available. However, that leaves only two cases: 1) if accept/discard of zero-checksum IS available, then VXLAN would configure it to accept 2) if accept/discard of zero-checksum is NOT available, then UDP *MUST* pass the zero-checksum packets to VXLAN. It's up to VXLAN to decide how to handle them - and it's OK to require VXLAN to MUST accept them (i.e., to treat them the same way as a valid non-zero checksum) When you have a stronger validation mechanism, I see no reason to drop packets with zero checksums for that reason alone - however, VXLAN really needs to say that *it* will do that drop if necessary, not to assume that UDP can be configured to do so. Joe
- [Tofoo] VXLAN (UDP tunnel protocols) and non-zero… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Gorry Fairhurst
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Behcet Sarikaya
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Behcet Sarikaya
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Larry Kreeger (kreeger)
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Larry Kreeger (kreeger)
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] [nvo3] VXLAN (UDP tunnel protocols) a… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Larry Kreeger (kreeger)
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Joe Touch
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Behcet Sarikaya
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Joe Touch
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Behcet Sarikaya
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Joe Touch
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Stewart Bryant
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Joe Touch
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Joe Touch
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Joe Touch
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Tom Herbert
- Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-… Joe Touch