Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01
Mark Allman <mallman@icir.org> Fri, 15 May 2009 12:36 UTC
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From: Mark Allman <mallman@icir.org>
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Subject: Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01
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> I don't like the part about tracking the seqnum edges. > > Why would someone send 400 byte packets when the MSS is 1400+? Something interactive like ssh. Why do we give apps the chance to turn off Nagle? It's a big, ugly world with a vast range of behavior. > How does this interact with the Nagle algorithm? As sketched in the draft ... + You can use a byte-based variant of ER which assumes MSS-sized packets. As discussed in the draft this *can* have precision problems in terms of determining the number of packets outstanding in the network and therefore when ER should and should not be used. In particular, if Nagle is turned off and so short packets are being sent then ER can get confused (see two examples in section 2.1. + Given that there can be a lack of precision we note that a TCP could in fact track the three packets on the right side of the window (four sequence numbers) to fully grok how many packets are in the network [*] and therefore to more accurately trigger ER. This in particular helps when Nagle is in use. I am not clear what you are getting at by an 'interaction'. I don't think ER interacts with Nagle, but the packet-based variant does cope with Nagle. [*] Obviously tracking only the right side of the window doesn't give you a fine-grained notion of how many packets are in the network in total. It tells you that either (a) there are at least four (and so we're out of the ER regime) or (b) there are less than four outstanding packets and how many there actually are. So, it works for ER's purpose. allman
- [tcpm] WGLC on draft-ietf Eddy, Wesley M. (GRC-RCN0)[Verizon]
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt Eddy, Wesley M. (GRC-RCN0)[Verizon]
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Eddy, Wesley M. (GRC-MS00)[Verizon]
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Iljitsch van Beijnum
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Mark Allman
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Eddy, Wesley M. (GRC-MS00)[Verizon]
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Iljitsch van Beijnum
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Eddy, Wesley M. (GRC-MS00)[Verizon]
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Mark Allman
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Iljitsch van Beijnum
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Mark Allman
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Iljitsch van Beijnum
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Mark Allman
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Joshua Blanton
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Yoshifumi Nishida
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Eddy, Wesley M. (GRC-MS00)[Verizon]
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Mark Allman
- Re: [tcpm] WGLC on draft-ietf-tcpm-early-rexmt-01 Eddy, Wesley M. (GRC-MS00)[Verizon]