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Date:      Wed, 18 Apr 2001 22:14:07 -0700
From:      Adi <lists@lists.grot.org>
To:        Barney Wolff <barney@databus.com>
Cc:        freebsd-net@freebsd.org
Subject:   Re: ICMP echo measurement discrepancy
Message-ID:  <20010418221407.A38525@mighty.grot.org>
In-Reply-To: <20010418154457.A58540@mx.databus.com>; from barney@databus.com on Wed, Apr 18, 2001 at 03:44:57PM -0400
References:  <20010418080531.A35252@mighty.grot.org> <20010418154457.A58540@mx.databus.com>

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Oops, I rearranged some text in my original message and left out the bit that
said that I see packet loss when the SDSL line encapsulation is set to be
bridged ethernet over ATM (RFC1483).

That said, I power-cycled my router and the packet loss seems to have gone
away (herring. red.)

However, I have a different problem and this persists despite the power-cycle
-- if I use nmap -sT to initiate a TCP port scan, it succeeds on local hosts
(the router is running NAT) but not on "remote" hosts. If I run tcpdump I see
the SYN's going out but no ACK's coming back...in fact nothing comes
back...very odd as other tcp connections work fine, with the SDSL
encapsulation set to bridged or PPPoATM. Somehow, because the line
encapsulation is set to bridging,

Adi

On Wed, Apr 18, 2001 at 03:44:57PM -0400, Barney Wolff wrote:
> How many packets does fping send in a burst?  Perhaps it's too many
> for the router or switch to buffer, and they're getting dropped
> before ever leaving your site.  Your host can send them far faster
> than they can be transmitted over the sdsl link.
> 
> Barney Wolff
> 
> On Wed, Apr 18, 2001 at 08:05:31AM -0700, Adi wrote:
> > I have a SDSL 768K lightly loaded DSL circuit terminating on a Flowpoint 2200
> > SDSL router connected to an ethernet switch off of which I have 3 FreeBSD
> > machines:
> > 
> > <redback sms1000>---768K SDSL---<router>==[switch]===(FreeBSD machine)
> > 
> > I also control the ISP end of the DSL circuit. Depending on the *line
> > encapsulation of the SDSL circuit*, different programs running ICMP echo
> > report different packet loss rates with otherwise the _exact_ same setup.
> 

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