Re: [tsvwg] Switch testing at 25G with ECN --SCE Draft

[Greg White <[e-mail]>]

Agreed.  I would not expect any different result either, which begs the question why does SCE need two different signals (ECT(1) and CE) in a datacenter environment?

-Greg



On 8/9/19, 3:43 PM, "Scaglione, Giuseppe" <[e-mail]> wrote:

    Greg,
    
    We are working -- and in beta -- with having the switch natively set SCE bits instead of CE and removing the iptable configuration on the target server.  Yet, I do not expect any different result since the TCP-SCE stack would react the same.
    
    Regards,
    Giuseppe Scaglione
    
    
    -----Original Message-----
    From: Greg White [mailto:[e-mail]] 
    Sent: Friday, August 9, 2019 2:36 PM
    To: Jonathan Morton <[e-mail]>; Scaglione, Giuseppe <[e-mail]>
    Cc: [e-mail]; [e-mail]
    Subject: Re: [tsvwg] Switch testing at 25G with ECN --SCE Draft
    
    Right.  Per the SCE method, the switch would mark ECT(1) using a ramp, and then when the ramp would exceed 100% marking, it would change to using CE.  
    
    The implementation discussed here marks CE using a ramp, and when the ramp would exceed 100% marking, it changes to packet drop.  This, as you said, is simply RFC3168 ECN marking, not SCE ECN marking.
    
    I was just trying to set the record straight.  There was a claim made that a switch vendor had implemented SCE-style packet marking in hardware at 25Gbps, which wasn't accurate.
    
    -Greg
    
    
    
    On 8/9/19, 2:58 PM, "Jonathan Morton" <[e-mail]> wrote:
    
        > On 9 Aug, 2019, at 11:44 pm, Scaglione, Giuseppe <[e-mail]> wrote:
        > 
        >>> Just to be super clear, this isn't a hardware implementation of SCE running at 25Gbps.
        > 
        > I am not sure I follow. The Test setup section of the paper clearly describes the hardware used -- severs, switch, cables. 
        > What I cannot disclose at this point is the exact model and characteristics of the HPE Aruba Switch used. Yet, it is a "real" Ethernet Switch, providing 25Gbps connectivity, configured to do bridging across the four ports and implementing RFC3168 with the ECN remarking configuration described in my previous email and on the paper.
        
        I think the issue is with the way the switch itself marks with CE, not ECT(1).  It's a limitation I think is worth acknowledging and, hopefully, finding a way to remove.
        
         - Jonathan Morton