Subject: RE: [IMRG] directing the discussion

From: "Loki Jorgenson" <[email-masked]>
Date: Wed, 16 Mar 2005 14:57:19 -0800

All well received.

And I would add to your list of "who needs to the information" -
applications people or people involved in applications research.  These
people are neither experimenting on the Internet or running the
Internet.  But they are involved in work that has a direct dependency on
the Internet and networks in general.  And they need to characterize the
beast for their own purposes.

This is where I find the "rubber hits the road" and defines relevant
metrics.  And I imagine it is where some very interesting
cross-pollination can take place (networking and.... something).

-----Original Message-----
From: Jennifer Rexford [mailto:[email-masked]] 
Sent: Wednesday, March 16, 2005 2:52 PM
To: Loki Jorgenson
Cc: [email-masked]
Subject: RE: [IMRG] directing the discussion

-----8< --- snip -----------

In terms of the important question of "who needs the information," I
think
we have at least two camps -- those using data to characterize the beast
(e.g., research folks trying to do experimental science on the Internet,
including work on understanding the performance and limitations of our
existing protocols and/or evaluate new designs) and those using data to
run
the network (e.g., operators trying to detect anomalies, do traffic
engineering, thwart attacks, etc.), though increasingly the lines are
blurry
as more research folks jump in to creating and evaluating techniques for
using measurement data to help operators.

-- Jen

_______________________________________________
IMRG mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/imrg

---

From: "Tom Petch" <[email-masked]>
Date: Thu, 17 Mar 2005 12:16:17 +0100

I see IETF WG as customers, who could take better decisions if better data were
available.

In no particular order

routing; there seems very little analysis of BGP and how it is used, what gets
advertised how (thinking particularly of what does not get advertised and how,
eg by aggregation or by communities and the AS_PATH of the advertisement v the
path that data takes) - probably the one that interests me most but is also the
most abstruse (I am aware of potaroo and the sterling work of Philip Smith)

traffic by application; one frequent discussion point with spam/UBE is the
notion that operators do not care because this is such a small part of the load,
BitTorrent and such like being the majority use of the Internet; true or false?

TCP(M); much discussion about the resetting of sessions, what that costs (slow
start etc), would it be better to behave differently in the event of unexpected
happenings (RST, ICMP); how frequent are these events?

segment sizes; crops up in IPv6 and network management; when 576 is too small,
how many networks lose out if the effective minimum PDU needs to be something
bigger?

congestion; until the advent of wireless, 'everyone knew' that packet loss was
due to congestion and not to CRC checks; I have looked periodically for papers
to support this and do not see them; and is wireless quite different, if so by
how much?

how bit is the Internet in terms of traffic, how fast is it growing?  there was
a question on this on the main IETF list some months ago, I never saw a reply.

not rocket science, mostly

Tom Petch

----- Original Message -----
From: "Loki Jorgenson" <[email-masked]>
To: "Jennifer Rexford" <[email-masked]>
Cc: <[email-masked]>
Sent: Wednesday, March 16, 2005 11:57 PM
Subject: RE: [IMRG] directing the discussion

All well received.

-----Original Message-----
From: Jennifer Rexford [mailto:[email-masked]]
Sent: Wednesday, March 16, 2005 2:52 PM
To: Loki Jorgenson
Cc: [email-masked]
Subject: RE: [IMRG] directing the discussion

-- Jen

---

From: "Jennifer Rexford" <[email-masked]>
Date: Thu, 17 Mar 2005 07:54:34 -0500

Loki,

> the AS_PATH of the advertisement v the

Hi.  On the forwarding vs. signaling path, you might be interested in the
papers

  http://www.cs.princeton.edu/~jrex/papers/sigcomm03.pdf
  http://www.cs.princeton.edu/~jrex/papers/infocom04.pdf

See also the slides at

  http://www.cs.princeton.edu/~jrex/talks/astrace04.ppt

These papers focus mostly on the difficulty of accurately determining the AS
path the packets actually take, but they also discuss cases where the
forwarding and signaling paths legitimately differ (e.g., due to route
aggregation, packet deflections, and bogus ASes in the BGP AS path).
Actually, our intent when we started this work was to focus soley on
analyzing the cases where they differ, but we found so many mismatches
between the traceroute and BGP data when we applied a prefix-to-AS mapping
(gleaned from the origin ASes in BGP routing tables) to the IP addresses in
the traceroute paths that we had to step back and consider the problem of
how to construct a more accurate prefix-to-AS mapping to use.  The biggest
problem was caused by ASes that do not advertise the address blocks they use
to number their equipment, causing the addresses to be wrongly mapped to
whatever upstream provider is advertising the supernet containing these
addresses (e.g., see slide #12 in the powerpoint talk above).

-- Jen

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Tom
Petch
Sent: Thursday, March 17, 2005 6:16 AM
To: Loki Jorgenson
Cc: [email-masked]
Subject: Re: [IMRG] directing the discussion

I see IETF WG as customers, who could take better decisions if better data
were
available.

In no particular order

routing; there seems very little analysis of BGP and how it is used, what
gets
advertised how (thinking particularly of what does not get advertised and
how,
eg by aggregation or by communities and the AS_PATH of the advertisement v
the
path that data takes) - probably the one that interests me most but is also
the
most abstruse (I am aware of potaroo and the sterling work of Philip Smith)

traffic by application; one frequent discussion point with spam/UBE is the
notion that operators do not care because this is such a small part of the
load,
BitTorrent and such like being the majority use of the Internet; true or
false?

TCP(M); much discussion about the resetting of sessions, what that costs
(slow
start etc), would it be better to behave differently in the event of
unexpected
happenings (RST, ICMP); how frequent are these events?

segment sizes; crops up in IPv6 and network management; when 576 is too
small,
how many networks lose out if the effective minimum PDU needs to be
something
bigger?

congestion; until the advent of wireless, 'everyone knew' that packet loss
was
due to congestion and not to CRC checks; I have looked periodically for
papers
to support this and do not see them; and is wireless quite different, if so
by
how much?

how bit is the Internet in terms of traffic, how fast is it growing?  there
was
a question on this on the main IETF list some months ago, I never saw a
reply.

Tom Petch

----- Original Message -----
From: "Loki Jorgenson" <[email-masked]>
To: "Jennifer Rexford" <[email-masked]>
Cc: <[email-masked]>
Sent: Wednesday, March 16, 2005 11:57 PM
Subject: RE: [IMRG] directing the discussion

All well received.

-----Original Message-----
From: Jennifer Rexford [mailto:[email-masked]]
Sent: Wednesday, March 16, 2005 2:52 PM
To: Loki Jorgenson
Cc: [email-masked]
Subject: RE: [IMRG] directing the discussion

-- Jen

---

From: stanislav shalunov <[email-masked]>
Date: 17 Mar 2005 09:19:38 -0500

"Tom Petch" <[email-masked]> writes:

> traffic by application; one frequent discussion point with spam/UBE
> is the notion that operators do not care because this is such a
> small part of the load, BitTorrent and such like being the majority
> use of the Internet; true or false?

True.  See http://netflow.internet2.edu/weekly/ (the mail category
includes all email-related protocols that can be easily identified).

Spam is a huge problem, but the resource it consumes most is human
time and attention, but network capacity.  In other words, only very
indirectly a problem for a backbone operator.

What I find puzzling about this question is that the purported
recipients of the answer are operators.  Doesn't every operator worth
half a bronze bit know how much email consumes in capacity on his
network?

-- 
Stanislav Shalunov		http://www.internet2.edu/~shalunov/

Just my 0.086g of Ag.

---

From: [email-masked]
Date: Fri, 18 Mar 2005 09:30:03 +0100

[email-masked] said:
> was due to congestion and not to CRC checks; I have looked periodically for
> papers to support this and do not see them; and is wireless quite different,
> if so by how much? 

Not exactly research, but here are some observations :
a characteristic of WLANs seem to be not packet loss but variable delay due
to retransmission. Layer 2 is restransmitting unicast. Multicast
is not retransmitted and we do see big loss rates.

In our MAN-WAN we have statistics showing a consistent high loss/retransmission 
rates in the order of 10s of percents and accordingly highly variable roundtrips times.

regards
  Olav