SUNET Internet2 Land Speed Record:
124.935 Pbmps (single stream).

From San Jose, CA, USA to Luleå, Sweden

Swedish University Network

Börje Josefsson 2004-09-12


SUNET is the organization for the national higher research and education network (NREN) of Sweden. SUNET operates the GigaSunet network, which is built with 10 Gbit/sec DWDM connections in a redundant infrastructure, connecting PoPs in 22 cities, nationwide, and using redundant 2,5 Gbit/sec connections as access towards the universities. It is used by researchers, teachers, students, and administrative personnel on 32 universities and colleges nationwide. In addition to this, some central government museums and external organizations are also connected to the network.

Internet Land Speed Record:

On September 12, 2004, SUNET transferred around 1831 Gigabytes of data (corresponding to approx. 2800 CD:s) in about one hour, using a single TCP stream between one host at the Luleå University of Technology (LTU) in Sweden (close to the Arctic circle), and one host connected to a Sprint PoP in San Jose, CA, USA. The network path used is the GigaSunet backbone - shared with other users of the Swedish universites, and the SprintLink core network, used by all the customers of Sprintlink.

The transfer was done with the ttcp program, available for many different platforms. We have chosen to use NetBSD for our tests, due to the scalability of the TCP code. ttcp is usually included in Unix and Linux systems. Windows users can download a Win32 version from pcusa.

Network setup:

Network path:

The path spans across two continents, Europe and the US, in adition to crossing the Atlantic three times(!), as shown in this picture:

traceroute to (, 64 hops max, 40 byte packets
1 ( 2.554 ms
2 ( 3.927 ms
3 ( 2.362 ms
4 ( 2.496 ms
5 ( 42.365 ms
6 ( 42.429 ms
7 ( 53.072 ms
8 ( 53.176 ms
9 ( 103.180 ms
10 ( 103.314 ms
11 ( 105.730 ms
12 ( 105.512 ms
13 ( 125.224 ms
14 ( 125.547 ms
15 ( 148.753 ms
16 ( 148.658 ms
17 ( 148.627 ms
18 ( 219.872 ms
19 ( 369.752 ms
20 ( 229.642 ms
21 ( 403.593 ms
22 ( 239.534 ms
23 ( 254.658 ms
24 ( 245.388 ms
25 ( 248.710 ms
26 ( 261.456 ms
27 ( 456.846 ms
28 ( 253.476 ms
29 ( 390.525 ms
30 ( 322.420 ms
31 ( 322.506 ms
32 ( 324.196 ms
33 ( 324.173 ms
34 ( 401.493 ms
35 ( 409.121 ms
36 ( 409.234 ms
37 ( 416.407 ms
38 ( 416.737 ms
39 ( 416.692 ms
40 ( 418.342 ms
41 ( 421.155 ms
42 ( 436.836 ms
43 ( 436.656 ms

PING ( 56 data bytes
64 bytes from icmp_seq=0 ttl=213 time=436.593 ms
64 bytes from icmp_seq=1 ttl=213 time=436.647 ms
64 bytes from icmp_seq=2 ttl=213 time=436.626 ms

---- PING Statistics----
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 436.593/436.622/436.647/0.027 ms

All routers in the path are Cisco high-end routers, including two of the new CRS-1 routers. Note that this is a path shared with other users of the GigaSunet and Sprint networks! The following graph shows one of the links in the path during the day (several transmissions were done) - showing the record-traffic shared with the normal usage.


According to the Internet2 LSR contest rule #5A, IPv4 TCP single stream, we achieved the following results, using the upcoming 2.0 version of the NetBSD operating system, and using a MTU of 4470 bytes:

1966080000000 bytes in 3648.81 real seconds = 4310.62 Mbit/sec

The complete output from ttcp during the transmission as seen from the transmitter and the receiver. The test run lasted 3648 seconds (1 hour, 48 seconds). Note that this means that we didn't loose a single bit on this path for the duration of the transmission!

A tcpdump output is available for the first few Mbytes of the transmission, both in raw tcpdump format and as readable tcpdump output.

Internet2 Land speed record submission:

According to contest rule #7, the distance should be calculated as the terrestrial distance between the cities where we do router hops. Referring to the Great Circle Mapper, the distance is 28,983 km (18,013 miles). We have then used the airport of the city in question as it's location.

Record submitted for the IPv4 single stream class is 124.935 Petabit-meters/second (which is a 78,6% increase of our previous record. also described here).

Most notable is perhaps that our result was achieved on the normal GigaSunet and Sprintlink production infrastructures, shared by millions of other users of those networks.

End system hardware and configuration:

The end hosts are off-the-shelf Dell PC:s (see details below), each with only a single Intel Xeon 2.0/2.8 GHz processor, 1024/512 Mbyte of RAM (sender/receiver), and using the Intel PRO/10GbE LR network adapters. Note that theese hosts are fairly modest in performance compared to any top-of-the line server of today, which makes this record even more impressive!

NetBSD operating system configuration (apart from default settings):

Kernel compile-time parameters:

Sysctl parameters:

Ifconfig settings:

ifconfig dge0 ip4csum tcp4csum udp4csum link0 link1 mtu 4470 up

We noted that it is the PC hardware (excluding the Intel PRO/10GbE network adapter) that is the limiting factor in our setup. The operating system, the network adapter, as well as the network itself, including the routers, are capable of handling more traffic than this, but the PCI-X bus and the memory bandwith in the end hosts are currently the bottlenecks.

Summary, according to Internet2 standards:

12 September 2004


Swedish University Network

Special thanks to:

Thanks to:

Also special thanks to Sprint for providing bandwidth, and for facilities and housing for the host in San Jose!

Contact information:

Hans Wallberg CEO, SUNET
Börje Josefsson CTO, SUNET. LSR test coordniator
Peter Löthberg Sprintlink LSR coordinator
Anders Magnusson LSR technical test manager.