Traceroute works fine. They seem to pass packets with source routing on;
i'm guessing this only because packets with source routing stuff on them
start getting consistently dropped on the backbones before packets without
source routing. Trying a few destinations, I can't actually get source
routing to do anything interesting.
Spoofed IP packets seem to work fine. Trying out this one was really
*bizarre*. I changed my IP address to an IP address that belongs to
William & Mary, back in Virginia, but then thought "oh no, i won't be able
to check to see if the packets get through, because i won't be able to log
into anywhere - my telnet packets will be sent to Virginia!" But, oddly,
my ssh connection to grad-pc.cs.washington.edu stayed up, even though i
had changed my IP address. So, using tcpdump on grad-pc26 i could see
pings and SYNs coming through from my machine's W&M IP address, even as
the tcpdump output was being sent thru ssh over a TCP connection to my
old, legitimate USWest IP address! I think i almost understand how that
worked - largely i guess b/c TCP demuxes incoming segments using an IP
address that it has stashed away in the PCB, and packets made it to my old
address thru ARP caching in my gateway. But why would my machine's IP
implementation accept non-broadcast/multicast IP packets that aren't
addressed to any of its interfaces? It seems like BSD would drop such
packets (vol 2, p. 218). Of course my machine is running Linux 2.0.32, but
glancing at the sources it seems like Linux should drop the packets
too [insert twilight zone theme here]...
neal
On Thu, 13 Aug 1998, Stefan Savage wrote:
> Sounds a bit faster than ISDN. The difference in BW you see may be due
> to compression. You might compare the BW you see sending a text file vs
> sending binary. I'm curious what USWest lets pass through their
> network... can you do traceroute? can you do it with the source route
> option turned on? Can you send spoofed IPgrams?
>
> - Stefan
>
> -----Original Message-----
> From: Neal Cardwell [mailto:cardwell@cs.washington.edu]
> Sent: Thursday, August 13, 1998 12:59 AM
> To: syn@cs
> Cc: Richard Fromm
> Subject: DSL rocks
>
>
>
> They finally got my DSL setup working today (a week after it was
> supposed
> to be on). I love it!! Never having had ISDN, i don't know how it
> compares with that, but i'm definitely happy with it...
>
> I ordered 256Kb, and i seem to be getting about 55KB/s=440Kb/s for long
> TCP transfers and 25KB/s=200Kb/s for short ones. It's interesting to me
> that their price list says they charge $62/mo for 512Kb but they seem to
> be letting me have a lot more than my 256Kb that i'm paying $40/mo for.
>
> Browsing the web is pretty close to the performance from Sieg. I suspect
> the web browsing goes well relative to a T3 because for small transfers
> TCP is RTT-limited, and the RTT is reasonably small thru USWest - about
> 20ms to MCI or Alternet in Seattle and 60ms to Silicon Valley through
> Alternet.
>
> If you're interested, here's the URL:
> http://www.uswest.com/com/customers/interprise/dsl/
>
> They said it would be (no bill yet :-) $110 setup fee, $40/mo for the
> "256Kb" line, $20/mo for the ISP (you can pick someone other than
> USWest).
> Plus whatever they're charging for the modems; i should be getting mine
> free through their early-bird promotional deal. Not sure if that's still
> on. The DSL modem just has a 10BaseT jack, and we're just getting IP
> addresses through DHCP, so i'm unning it through a hub and splitting the
> cost with my roomie.
>
> neal
>
>