Yes we also can psuh 800 mbps on a GB link Miktoik router to Mikrotik
Router. But the test initiates on a Jumbo frame device and end on a jumbo
frame device.
Now try this test....
Connect 4 computers each to its own 100mbps switch (support only 1500mtu),
Then take the 4 switches and plug into 100m/1000gb switch, then plug that
switch (9600MTU) to the end router on a GB ethernet port. Do a simultaneous
test from all 4 pcs to the end GB router, and see what you get. I bet
you'll find that the agreegate throughput is around 200mbps FDX.
Linux on most Ethernet ports will auto adjust its MTU, so testing in a lab
router to router may not show desired results as the testing PC will start
with Jumbo frames from the beginning.
.>Checking the router Interfaces show a 1500MTU setting
Because it is set to 1500MTU, does not necessarilly mean that it is pushing
only 1500 MTU. Many ethernet drivers are configured to allow larger size
packets to pass. I won;t try and try to explain that situation because I
will get it wrong.
The customer;s traffic is almost always using a 1500 MTU. so 1500 byte
packets or smaller is what will pass across any backbone transport links.
The gear must be capable of pushing the 1500 MTU packets at full speed. For
what ever reason it usually is NOT possible. Most GB gear will only push
full capacity when pushing Jumbo 9600 or greater packets.
Unless there is some sort of trunking mode that agreegates the packets.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: "Brad Belton" <[EMAIL PROTECTED]>
To: "'WISPA General List'" <wireless@wispa.org>
Sent: Saturday, January 06, 2007 11:50 PM
Subject: RE: [WISPA] Optimally taking advantage of GB Ethernet
Hello Tom,
First let me say....damn Cowboys...<sigh>
I'm not sure I follow exactly what you are saying, but we have pushed better
than 800Mbps HDX and more than 700Mbps FDX aggregate between GigE MT
routers. Checking the router Interfaces show a 1500MTU setting. Is that
what you are talking about?
Brad
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Travis Johnson
Sent: Saturday, January 06, 2007 10:43 PM
To: WISPA General List
Subject: Re: [WISPA] Optimally taking advantage of GB Ethernet
Tom,
How are the "big boys" doing it? Surely AT&T and others are transporting
more than 200Mbps across their 1GB fiber links.
Travis
Microserv
Tom DeReggi wrote:
Gigabit Ethernet, can pass 1 gbps when it uses greater than a 9600 MTU
frame.
But with a 1500MTU frame, it can barely pass 200 mbps.
The problem is that most Internet and subscriber traffic is using a
1500MTU or smaller frame.
So in theory, its would be just as efficient and fast to bond two 100
mbps fiber connections than it would to buy 1- 1GB fiber connection.
So the question is.... How do we most efficiently use 1GB fiber to get
the advantage of the full 1GB of capacity?
Do we need to use some sort of packet agreegation/stuffing technology?
Is GB etherner pointless for Internet transit backbones?
Is GB just good for high capacity Transports, recognizing that routers
will likely split traffic to different smaller bandwidth peers?
Is there a special router or router feature used to solve this problem?
Is that method available to Linux?
The reason I ask is several fold. In a network design where all
traffic flows to a single source (for example many 100mbps baclhauls
to remote areas to 1 central data center), it would be beneficial
because the cost of 1 big 1GB pipe could be shared to deliver capacity
to everything, better apt to handle peak traffic and get higher
oversubscription rates. However, if teh GB INternet pipe can not be
efficiently used, this method would be severally flawed. It might be
better to have multipel 100mvps transit connections spread out across
one's network, so there was a shorter path to transit, and the
network's bandwdith spread out amungst multiple 100mbps transit
connection, for better over all throughput. In other words, in a 10
city network, 1- 100mbps pipe in each of teh 10 cities would allow a
full combined 1 gbps of Internet transit, where as agregating 100mbps
from each city to one central source where their was a single 1GB
transit, would result in only a 200mbps throughput, assuming traffic
was delivered to it as a 1500 MTU.
Any feedback?
Take note that my comment that a 1500MTU frame 1 Gbps Ethernet card
could only pass 200kbps was based on some lab tests. With the 1500MTU
frame acheiving only 200kbps, our routers CPU utilization was less
than 20%, so it was not a saturated router. The second we changed MTU
to 9600, we got over 800 mbps, and CPU utilization was still very low,
forget exact number but under 40%. These tests were replicated going
PC to PC (no switch) and with a high end SMC GB switch in-line.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
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