RE: [RPRWG] RPR Perf: Non-uniform distribution
Hi Jeff,
I agree with you that there will probably not be high multi-homing within a
MAN ring in the near term. A more realistic scenario will most likely be 2
or more hubs (POPs) on the ring and unequal traffic going "off-ring" at each
hub. Do you have any suggestions for a set of realistic non-uniform traffic
patterns?
Thanks,
Komal
-----Original Message-----
From: Timbs, Jeffrey L (Jeff) [mailto:timbs@xxxxxxxxx]
Sent: Thursday, April 26, 2001 6:04 AM
To: 'stds-802-17@xxxxxxxx'
Subject: RE: [RPRWG] RPR Perf: Non-uniform distribution
Khaled et al:
I agree with Komal's suggestion below. I would like to see the behavior when
a large % of traffic goes "off-ring" through few (1 or 2) nodes. It has been
reported that pass-thru : add/drop traffic is higher than 80:20 due to the
long-distance nature of IP traffic. [Rodriguez-Moral et al, "Optical Data
Networking," Journal of Lightwave Technology, Vol. 18, No. 12, December
2000] A further implication is that most IP traffic is not terminated within
a MAN, leading to hot-nodes (or gateways) which are destinations of the
majority of traffic. Assuming that MAN rings are connected to backbone
networks via few (one or two) nodes, a high percentage of traffic will be
destined for these few nodes.
Some interesting points are that, of 100 "leading" websites, WorldCom could
carry traffic to up to 45 of them entirely on its own backbone while MCI
could reach 28 sites directly (Sprint, 18 sites). Also, 35 of the sites
were multi-homed on the WorldCom backbone. [cf. OECD pub
DSTI/ICCP/TISP(98)7/FINAL via http://www.oecd.org/dsti/sti/it/cm/index.htm]
It's not clear that there would be a high degree of multi-homing within a
MAN ring (an economical factor driven by localized demand). For a high
degree of destination stripping distributed across many nodes, several
services would need to be offered at many sites (POPs). To me, there is a
current assumption that new service providers want to populate as few POPs
as possible, so that traffic must be carried to a centrallized site within a
region which also decreases the likelihood of uniform distribution.
For near-term introduction of RPRs, we should consider that this traffic
pattern may be more representative of a MAN RPR and should consider the
impact on performance (due to lower overall spatial reuse).
Jeff Timbs
Agere Systems, Inc.
-----Original Message-----
From: Komal Rathi [mailto:krathi@xxxxxxxxxxxxxx]
Sent: Tuesday, April 24, 2001 1:50 PM
To: 'stds-802-17@xxxxxxxx'
Subject: [RPRWG] RPR Perf: Non-uniform distribution
Khaled and members of the Perf. Adhoc committee,
Given that all implementations seem to have destination stripping that
results in spatial reuse, it's not clear in my mind what we gain out of
running simulations with randomly and uniformly distributed
source/destination pairs. I believe that the uniform distribution will not
provide enough information that would help demonstrate the differences in
performance characteristics of various proposed architectures. All it does
is show that we get some spatial reuse, which we know all implementations
do.
I would like to suggest that we make the destination addresses distributed
non-uniformly which can show some more interesting performance
characteristics of various architectures that are being proposed. For
example, how about something like 80% to dest-A and some other distribution
to other destination nodes. Another idea would be to have 90% to neighboring
node A, and 10% to the other neighboring node B.
Komal Rathi
Lantern Communications