Dsxpnm Serial Interface

Having spent a fair amount of time on this type of thing recently, let meoffer a few thoughts-

With any type of speed testing, you must define the testing domain beforeyou start, or the numbers won't mean a thing. The reason for this is thatdelay between the endpoints affects max throughput, especially with regardsto TCP.

Interface s1/0 ip address x.x.x.x 255.255.255.0 ip route-cach flow dsu badnwidth 44210 On executing the sh int s1/0 command the follwoing is found Serial1/0 is up, line protocol is up Hardware ss DSXPNM Serial. Encapsulation HDLC, crc 16. 163959228 input errors, 163959228 CRC, 72386460 frame, 43881477 overrun, 0 ignored, 122414945 abort.
The errors seem to go both ways on serial 1 and are a mix of errors, both ways. As your ISP to provide a loop at demarc at both istes and check if the errors still happen. If you're error-free then their line is bad. The second serial (serial 2 to serial 6) shows serial 6 clean and serial 2 abort.
Routerl# show interface serial 3/0 Serial3/0 is up, line protocol is up Hardware is DSXPNM Serial Description: Sprint T3 Internet address is 10.2.100.2/30 MTU 4470 bytes, BW 9000 Kbit, DLY 200 usec, reliability 255/255, txload 77/255, rxload 26/255 Encapsulation HDLC, crc 16, loopback not set Keepalive set (10 sec).

Hardware is DSXPNM Serial Internet address is x.x.123.162/30 MTU 4470 bytes, BW 12631 Kbit, DLY 200 usec, reliability 255/255, txload 15/255, rxload 25/255 Encapsulation PPP, LCP Open Open: IPCP, crc 16, loopback not set Keepalive set (8 sec) Last input 00:00:13, output 00:00:03, output hang never Last clearing of 'show interface' counters 16:03:54.

With TCP windowing, a transmitting host can only transmit data up to thesize of the window of the receiving host before it has to stop and wait foran ACK. This is by design as when TCP was developed, the large pipes we havetoday weren't even on the drawing board.

The delay I mentioned above directly affects how long the transmitting hostsits idle waiting on an ACK, which of course affects throughput. This is whythe TCP window size should be tweaked to fit the pipe, and the max expecteddelay. This is also the reason why it's rare that a single TCP session willbe able to achieve the max throughput on a given high speed pipe.

There's some good research out there on the affect of TCP Window size onthroughput. Here's a couple to get you started-http://www-didc.lbl.gov/TCP-tuning/http://www.psc.edu/networking/projects/tcptune/

Dsxpnm Serial Interface App

Joe

On 1/10/08, Ramcharan, Vijay A <vijay.ramcharan at verizonbusiness.com> wrote:

If you just need to do a blind bandwidth test, it's possible to useiperf to test your link one-way outbound without really needing areceiver at the other end. See below for an example. You'd just need totweak the iperf settings to achieve your desired traffic rate. 10M belowmeans use a 10Mbps bandwidth. I ran 2 streams which would correspond tothe avg 20Mbps SUM bandwidth noted.If you have a few high speed Internet users you could probably testinbound as well. The test below was run from a Win2K server just behindthe router to an IP address reachable by that router across a DS3. Notethat iperf consumed 100% CPU on this server during the test so usecaution when testing.I've also tested locally and was easily able to generate 100Mbps oftraffic off my fairly fast PC.

Since you appear to want to gauge real max bandwidth possible you'llprobably want to try using TCP with a real receiver at the other end togather stats from both the iperf sender and receiver as well as yourrouter.

C:Program Filesiperf-2.0.2bin>iperf -c 192.168.255.21 -u -b 10m -P 2-f k -t 600

Dsxpnm Serial Interface Serial

------------------------------------------------------------Client connecting to 192.168.255.21, UDP port 5001Sending 1470 byte datagramsUDP buffer size: 63.0 KByte (default)

------------------------------------------------------------[ 4] local 63.91.167.53 port 1738 connected with 192.168.255.21 port5001[ 3] local 63.91.167.53 port 1737 connected with 192.168.255.21 port5001[ 4] 0.0-600.0 sec 729444 KBytes 9959 Kbits/sec[ 4] Sent 508130 datagrams[ 3] 0.0-600.0 sec 731400 KBytes 9986 Kbits/sec[ 3] Sent 509492 datagrams[SUM] 0.0-600.0 sec 1460844 KBytes 19945 Kbits/secread failed: Connection reset by peerread failed: Connection reset by peer[ 4] WARNING: did not receive ack of last datagram after 1 tries.[ 3] WARNING: did not receive ack of last datagram after 1 tries.

DS3-RTR5#sh int s2/0Serial2/0 is up, line protocol is up Hardware is DSXPNM Serial Internet address is 1.2.3.4/30 MTU 4470 bytes, BW 44210 Kbit, DLY 200 usec, reliability 255/255, txload 107/255, rxload 1/255 Encapsulation HDLC, crc 16, loopback not set Keepalive set (10 sec) ... 5 minute input rate 48000 bits/sec, 68 packets/sec 5 minute output rate 18560000 bits/sec, 3067 packets/sec...DSU mode 0, bandwidth 44210, real bandwidth 44210, scramble 0DS3-RTR5#

Vijay Ramcharan

-----Original Message-----From: cisco-nsp-bounces at puck.nether.net[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of omar parihuanaSent: January 09, 2008 11:57To: Michael Long; cisco-nsp at puck.nether.netSubject: Re: [c-nsp] How to measuse the throughput on Internet Links

Hi Michael,

thanks for your response....

I tried to use IPERF previously without success because set up theserverwas difficult for me. I'm looking for other options.

Thanks againRgds.

On 1/9/08, Michael Long <mlong at mikesoffice.org> wrote:

iperf. http://dast.nlanr.net/Projects/Iperf/

Although you'll need a client and server setup. Plus it helps if theserver is somewhat close to the link you are trying to test.

Mike

omar parihuana wrote:

Hi guys,

I bought a new Internet Link 40Mbps 1:1 that is provide withFastEthernetinterface, now, I would like to check if I have the 40Mbps

effective.

How

can I measure the max capacity of my Internet link? any suggestions?

Thanks in advanced...

Rgds.

-----------------Certified Networking Professionals make better Connections!

_______________________________________________cisco-nsp mailing list cisco-nsp at puck.nether.nethttps://puck.nether.net/mailman/listinfo/cisco-nsparchive at http://puck.nether.net/pipermail/cisco-nsp/