Subject: [Fwd: Re: TCP Performance Implications of Network Asymmetry]

From: John Border <[email-masked]>
Date: Mon, 19 Feb 2001 13:33:22 -0500

-------- Original Message --------
Subject: Re: TCP Performance Implications of Network Asymmetry
Date: Mon, 19 Feb 2001 10:10:57 -0500
From: John Border <[email-masked]>
To: [email-masked]
References: <[email-masked]>

>         1) What is the bandwidth asymmetry of your system?

We support multiple size pipes.  The current most extreme example is 45
Mbps:128 Kbps (351:1).

>         2) What technologies are used for the forward and return directions?

These are VSAT type networks.  In the forward direction, we use TDM with
concatenated Reed-Solomon plus Viterbi QPSK encoding (e.g. DVB).  In the
return direction, we use TDMA with various types of encoding (e.g. Viterbi
OQPSK).

>         3) Do you currently use any mechanism to mitigate the impact
>         of asymmetry.
> 
>         If so which technique to use ?
>         e.g.  (i) VJ Header Compression
>                 (ii) ACK modification schemes (ACK Filtering/Suppression)
>                 (iii) PEPs or application proxies

We use PEPs of various forms.  The PEPs implement a variety of mitigation
techniques including the ones you mention (VJ header compression and ACK
filtering).  We also use application proxies for HTTP traffic.