[j-nsp] J6350 Jumbo frame MTU and OSPF setting
Harris Hui
harris.hui at hk1.ibm.com
Mon Oct 4 05:07:25 EDT 2010
Hi Ben,
Thanks for your suggestion.
I had performed the iPerf UDP test, do you think is it normal for the
100Mbps link?
Host A (10.16.xx.58) <-----> EX 4200 Switch <------> J6350 (MTU 9018)
<----- Fiber circuit 100Mbps (from West to East coast ~80ms) ------> (MTU
9018) J6350 <------ EX 4200 Switch ------> Host B (10.26.xx.60)
root at xxxxxxx bin]# ./iperf -c 10.26.xx.60 -t 60 -u -b 100M
------------------------------------------------------------
Client connecting to 10.26.xx.60, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 126 KByte (default)
------------------------------------------------------------
[ 3] local 10.16.xx.58 port 48543 connected with 10.26.xx.60 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-60.0 sec 719 MBytes 101 Mbits/sec
[ 3] Sent 512816 datagrams
[ 3] Server Report:
[ 3] 0.0-60.0 sec 656 MBytes 91.7 Mbits/sec 0.206 ms 45108/512815
(8.8%)
[ 3] 0.0-60.0 sec 1 datagrams received out-of-order
[root at xxxxxxx bin]# ./iperf -c 10.26.xx.60 -t 60 -u -b 70M
------------------------------------------------------------
Client connecting to 10.26.xx.60, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 126 KByte (default)
------------------------------------------------------------
[ 3] local 10.16.xx.58 port 25968 connected with 10.26.xx.60 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-60.0 sec 501 MBytes 70.0 Mbits/sec
[ 3] Sent 357143 datagrams
[ 3] Server Report:
[ 3] 0.0-60.0 sec 501 MBytes 70.0 Mbits/sec 0.276 ms 0/357142
(0%)
[ 3] 0.0-60.0 sec 1 datagrams received out-of-order
[root at xxxxxxx bin]# ./iperf -c 10.26.xx.60 -t 60 -u -b 80M
------------------------------------------------------------
Client connecting to 10.26.xx.60, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 126 KByte (default)
------------------------------------------------------------
[ 3] local 10.16.xx.58 port 31085 connected with 10.26.xx.60 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-60.0 sec 572 MBytes 80.0 Mbits/sec
[ 3] Sent 408164 datagrams
[ 3] Server Report:
[ 3] 0.0-60.0 sec 568 MBytes 79.4 Mbits/sec 0.221 ms 2961/408163
(0.73%)
[ 3] 0.0-60.0 sec 1 datagrams received out-of-order
Thanks
- Harris
|------------>
| From: |
|------------>
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|Ben Dale <bdale at comlinx.com.au> |
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|------------>
| To: |
|------------>
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|Harris Hui/Hong Kong/IBM at IBMHK |
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|------------>
| Cc: |
|------------>
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|juniper-nsp at puck.nether.net |
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|------------>
| Date: |
|------------>
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|04/10/2010 07:56 AM |
>--------------------------------------------------------------------------------------------------------------------------------------------------|
|------------>
| Subject: |
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>--------------------------------------------------------------------------------------------------------------------------------------------------|
|Re: [j-nsp] J6350 Jumbo frame MTU and OSPF setting |
>--------------------------------------------------------------------------------------------------------------------------------------------------|
Hi Harris,
However, increasing the MTU size on both the J6350s may not be able
to get a better TCP throughput, because the Host NICs and Switchport
are also using MTU 1500 right? Should I change the MTU size on Host
NICs and Juniper EX switches to MTU 9018 in order to prevent the
frame fragmentation happened below 9018?
There should be no more drops if your end devices are 1500 MTU and the
"core" network is 9018. As for your throughput, that is a little harder to
calculate, but the figures you are quoting seem quite low even with 80 ms
latency.
Latency aside, you should be able to easily saturate a 100Mbps pipe with
1500 byte frames on a J6350 without issue (in terms of PPS). I don't
believe adjusting the MTU size is going to make that much difference, but
it is worth trying. I would be inclined to kick off iperf with a UDP test
with 1500 byte frames to see what throughput you can get out of the pipe
first, then start investigating TCP/MSS issues.
Cheers,
Ben
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