I plan to design a hub and spoke WAN using ATM. The
data traversing the WAN is US equities market data.
Market data can be in two flavors multicast and TCP
client/server. Another facet of market data is it is
bursty in nature and is very sensitive to packet loss
and latency (like voice). What type of ATM AAL format
would be best for this topology? Is there any other
concerns I should be aware of.
Thx,
Philip
Philip Lavine wrote:
I plan to design a hub and spoke WAN using ATM. The
data traversing the WAN is US equities market data.
Market data can be in two flavors multicast and TCP
client/server. Another facet of market data is it is
bursty in nature and is very sensitive to packet loss
and latency (like voice). What type of ATM AAL format
would be best for this topology? Is there any other
concerns I should be aware of.
Maybe the small fact that ATM is fading away and building new networks with technology going away is going to explode your operational cost in a few years time. Business grade IP networks will provide you with equal if not better performance than a "dedicated" ATM WAN.
(in addition to the fact that you probably posted your question in the wrong forum)
Pete
Maybe the small fact that ATM is fading away and building new networks
with technology going away is going to explode your operational cost in
a few years time. Business grade IP networks will provide you with equal
if not better performance than a "dedicated" ATM WAN.
And being replaced with .... ? GigE? DPT/RPR? MPLS?
ATM is a great technology... Unfortunately, I don't think it was ever
fully utilized.. From what I understand, MPLS takes some of the good
bits and combines it with traditional routing.. But I don't see a lot
of MPLS implementations either...
look to the private networks luke... Seriously, many large private
ATM/Frame networks are transitioning to MPLS networks because the ATM or
Frame gear is/was/will-be-shortly EOL/EOS from the vendors. The costs to
run these networks don't jibe well with the alternatives.
Now, start the discussion on: "private network" and "mpls vpn" and "oops,
hey, that runs over the same routers as that bad-old Internet thing with
the haxors and such!"
ATM is a great technology.
indeed! i use them often. remember when you had to go into the
bank and wait in a queue for a teller?
randy
look to the private networks luke... Seriously, many large private
ATM/Frame networks are transitioning to MPLS networks because the ATM or
Frame gear is/was/will-be-shortly EOL/EOS from the vendors. The costs to
run these networks don't jibe well with the alternatives.
I figured MPLS was going to be the answer.. 
Now I must learn,
research, implement, and debug!
Now, start the discussion on: "private network" and "mpls vpn" and "oops,
hey, that runs over the same routers as that bad-old Internet thing with
the haxors and such!"
Heh...
indeed! i use them often. remember when you had to go into the
bank and wait in a queue for a teller?
Hopefully soon to be replaced with RFID machines with voice activated
commands..
Speaking of which.. It's 2005.. Where's my flying car?
ATM is a great technology.
indeed! i use them often. remember when you had to go into the
bank and wait in a queue for a teller?
When FIX-East was in College Park (Maryland), FIX-E was in an building NSI (as in NASA Science Internet) labelled the "Maryland National Bank" building. It appeared on all the network map slides.
Q&A time -
"Why have you hooked up a bank building?"
"Because of ATM"
"What does that get you?"
"It's how we get our funding from HQ."
So why didn't John Walton give that guy some money?</ot>
Cheers,
-- jra
O ye of little packets (or cells), if you are going to complain about the question at least answer it.
ATM Adaptation Layer (AAL) 1, 2, 3 / 4 and 5
AAL 1 – CBR constant bit rate traffic for voice trunks and video.
AAL 2 – VBR variable bite rate with a timing relationship between sender and receiver aka voice over ATM VBR Codec.
AAL 3 / 4 – VBR traffic with no timing relationship between sender and receiver allows both connection oriented and connectionless traffic types.
AAL 5 – is a thinner interface for those bearer services that do not require the services of AAL 3 / 4 it also has Available Bit Rate to take up any excess capacity in the circuit.
From an engineering and implementation perspective, which vendor’s equipment do you want to use and how do they implement AAL services.
In general on the ATM edge devices and switches I have worked on the propagation delay was 15 to 20 micro seconds per switch or edge device. Assuming your data will be traversing one to two switches at each end and several in the WAN then you can expect reasonably fixed delays of 150 to 200 micro seconds with jitter parameters of less than 5 -10 micro seconds not including speed of light issues.
With routers you will need to turn buffering off and you will still have propagation in the double to triple milli-seconds range with jitter in the multi milli-seconds range.
With ATM you setup your VPI/VCI combinations and with current ATM equipment look at QOS for both the overall VPI and different VCCs. For widely disparagent QoS parameter sets, setup a separate VPI for each parameter set.
For an ATM circuit you can setup either a uni-directional channel or a bidirectional pair of channels with either symmetric or asymmetric bandwidth. You can setup either a point to point or point to multipoint configuration. With current ATM switches you can setup one VPI/VCI channel for a single channel distribution until you get to a common switch closest to the customer where that switch can replicate the ATM cell stream to as many output ports as required to minimize duplicate streams of data in the network.
Having been one of the MPLS “experts” as the vendors were building the equipment trying to do ATM style of QoS at layers three and four does not work. IP needs to enhance the PPP (point to point protocol) that runs on serial links such as POS to Muti-channel PPP. Multi-link PPP was developed to bond smaller channels together to have a larger one. MCPPP needs to implement SAR for different size packets to be able to run VoIP and large 2k, 4k, 8k and 16k packets on the same serial link. Several major router vendors have implemented their routers as large cell switches with packet SARing at input and exit. They have also implemented proprietary inter router links that keep the packets in cell form until they leave the companies routing domain. These cell switching routers use larger cell sizes than ATM but the switching is extremely fast with most of the qos and routing table functions occurring on the interface cards in either standard or custom network processors.
Being an “Enganeer” I want to apply the right tool to the right job. Tools come and go.
First there was point to point and then circuit switched. Then packet route, point to point rings, broadband circuit switched, broadband packet route and switch, fiber based point to point with WDM and DWDM.
ATM gave us zero hop routing of IP packets from ingress to egress Ethernet.(who cares about the overhead since typical IP packets have more overhead in them than ATM cells) Fiber DWDM with ROADM and the like will give us zero hop optical routing of IP packet streams from ingress IP aggregation point to egress point. This will probably use GMPLS with the L being a lambda not a label but who knows.
Time to get off my White hobby horse and go back to work.
If you have any questions e-mail me directly.
John (ISDN) Lee
I Still Do not kNow
Its Suites Dennis’s Needs
Philip Lavine wrote:
Please elaborate why a router would have multi-millisecond propagation delay. For a 2meg link yes, for highspeed interfaces, no.
Mikael Abrahamsson wrote:
With routers you will need to turn buffering off and you will still have propagation in the double to triple milli-seconds range with jitter in the multi milli-seconds range.
Please elaborate why a router would have multi-millisecond propagation delay. For a 2meg link yes, for highspeed interfaces, no.
My ping is showing that!
(couldn't resist)
Pete
philip,
did you get any useful information? nanog-l is quite good at telling you
how they would redesign your network, as opposed to actually answering
your question.
contact offlist if you still need atm help.
/bmj