Browse Prior Art Database

Enhance the online response time through ATM service with ATM TA

IP.com Disclosure Number: IPCOM000016427D
Original Publication Date: 2003-Jan-10
Included in the Prior Art Database: 2003-Jun-21
Document File: 4 page(s) / 157K

Publishing Venue

IBM

Abstract

Disclosed is a method for enhancing the online response time through ATM service with ATM TA. It makes the online response time faster that one sets ATM TA's line clock rate with high speed rate and uses the packet leve shaping function of the router with lower rate.

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Enhance the online response time through ATM service with ATM TA

Two Problems with ATM TA

There are two problems when one uses ATM line service with ATM TA.

1. In case of ATM line with ATM-TA the online response time is as twice as it of leased line.
2. Under UDP traffic the online response time will become 8 seconds.

When we use 1500 byte ping as the online response time simulation tool, we can measure the response time as below
under the configuration of Figure 1. The test result is described below.

maxim um 1500 byte ping response time
(m s)

Cases

Leased line 210       without U D P

ATM Service 460       withoutU D P

       with U D P

8000

【Figure 1】

ping

UDP

Data Center Remote office

 OC3 155Mbps

V.35 HDLC

      ONU 7206 TA

25Mbps

128Kbps

ATM Network

2651

Traffic Generation Tool

Analysys of these two problems

ATM TA segments frames into 48 byte data and assembles 53 byte ATM cells. So,
ATM TA uses
lower clock rate than the ATM line clock rate as described in the Figure 2.

1

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Page 2 of 4

【Figure 2】

ping

128Kbps

128Kbps 112Kbps

112Kbps

7206 TA 2651

Data Center Remote office

Traffic Generator

1500byte

After the TA receives whole frames, TA segments frames into 48 byte data and assembles 53 byte cells.

Normally ATM TA uses about 0.85 clock rate of ATM line.
For example, in case of 128Kbps ATM line ATM TA uses 112Kbps clock rate.

1. After the ATM TA receives whole frames ATM TA send ATM cells into ATM line.
So, the whole sending time is as over twice as it of leased line as described
in the Figure 3.

Therefore the store and forward of low clock rate is the cause of the problem
No.1.

【Figure 3】

ping

128Kbp

2.·As the result of flie transfer from the Data Center with 1500 byte frames,
the Center router can sends traffic with 113Kbps throughput, because the ATM
cell header overhead
of the long frames is smaller than the small frames.

As the result of it traffic is stored in the ATM TA's buffer. So, although the
center router sends
critical traffic faster than the other, the critical traffic response time
will be much longer as described in the Figure 4.

Therefore the difference of the real bandwidth through ATM line with the
bandwidth of the serial line is the Problem No.2.

112Kbps

128Kbps 112Kbps

7206 TA 2651

Data Center

remote of...