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<p>Hi Ben,<br>
<br>
Thanks for your hits. I can configure the fiber PIMs to MTU 9018 and able to ping other J6350 with ICMP packet over 8000 bytes with do-not-fragment.<br>
<br>
Physical interface: ge-3/0/0, Enabled, Physical link is Up<br>
Interface index: 152, SNMP ifIndex: 184<br>
Description: <br>
Link-level type: Ethernet, MTU: 9018, Speed: 1000mbps, BPDU Error: None, MAC-REWRITE Error: None,<br>
Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Disabled,<br>
Remote fault: Online<br>
Device flags : Present Running<br>
Interface flags: SNMP-Traps Internal: 0x4000<br>
Link flags : None<br>
CoS queues : 8 supported, 8 maximum usable queues<br>
Current address: b0:c6:9a:87:35:36, Hardware address: b0:c6:9a:87:35:36<br>
Last flapped : 2010-09-27 02:32:24 UTC (5d 01:50 ago)<br>
Input rate : 0 bps (0 pps)<br>
Output rate : 1672 bps (3 pps)<br>
Active alarms : None<br>
Active defects : None<br>
<br>
ping XXX.XXX.XXX.254 size 8976 do-not-fragment <br>
PING XXX.XXX.XXX.254 (XXX.XXX.XXX.254): 8976 data bytes<br>
8984 bytes from XXX.XXX.XXX.254: icmp_seq=0 ttl=64 time=77.341 ms<br>
8984 bytes from XXX.XXX.XXX.254: icmp_seq=1 ttl=64 time=77.758 ms<br>
8984 bytes from XXX.XXX.XXX.254: icmp_seq=2 ttl=64 time=77.487 ms<br>
^C<br>
--- XXX.XXX.XXX.254 ping statistics ---<br>
3 packets transmitted, 3 packets received, 0% packet loss<br>
round-trip min/avg/max/stddev = 77.341/77.529/77.758/0.173 ms<br>
<br>
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?<br>
<br>
Please advise.<br>
<br>
Thanks<br>
- Harris<br>
<br>
<br>
<img width="16" height="16" src="cid:1__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt="Inactive hide details for Ben Dale ---10/01/2010 PM 07:46:23---Hi Harris My apologies, I completely missed the fact that you we"><font color="#424282">Ben Dale ---10/01/2010 PM 07:46:23---Hi Harris My apologies, I completely missed the fact that you were using fiber PIMs - maximum MTU for these is 9018 or 9014 if</font><br>
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<font size="2" color="#5F5F5F">From:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt=""><br>
<font size="2">Ben Dale <bdale@comlinx.com.au></font></td></tr>
<tr valign="top"><td width="1%"><img width="96" height="1" src="cid:2__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt=""><br>
<font size="2" color="#5F5F5F">To:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt=""><br>
<font size="2">Harris Hui/Hong Kong/IBM@IBMHK</font></td></tr>
<tr valign="top"><td width="1%"><img width="96" height="1" src="cid:2__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt=""><br>
<font size="2" color="#5F5F5F">Cc:</font></td><td width="100%" valign="middle"><img width="1" height="1" src="cid:2__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt=""><br>
<font size="2">juniper-nsp@puck.nether.net</font></td></tr>
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<font size="2" color="#5F5F5F">Date:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt=""><br>
<font size="2">10/01/2010 PM 07:46</font></td></tr>
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<font size="2" color="#5F5F5F">Subject:</font></td><td width="100%"><img width="1" height="1" src="cid:2__=C7BBFD23DF8440858f9e8a93df93@hk1.ibm.com" border="0" alt=""><br>
<font size="2">Re: [j-nsp] J6350 Jumbo frame MTU and OSPF setting</font></td></tr>
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<br>
<font size="4">Hi Harris</font><br>
<br>
<font size="4">My apologies, I completely missed the fact that you were using fiber PIMs - maximum MTU for these is 9018 or 9014 if you have the multi-port version:</font><br>
<br>
<a href="http://www.juniper.net/techpubs/software/junos-security/junos-security10.0/junos-security-swconfig-interfaces-and-routing/interfaces-physical-properties-section.html#interfaces-mtu-section"><u><font size="4" color="#0000FF">http://www.juniper.net/techpubs/software/junos-security/junos-security10.0/junos-security-swconfig-interfaces-and-routing/interfaces-physical-properties-section.html#interfaces-mtu-section</font></u></a><br>
<br>
<font size="4">On 01/10/2010, at 8:36 PM, Harris Hui wrote:</font><br>
<ul>
<ul><font size="4">Hi Ben,<br>
<br>
Looks like I can apply the MTU setting on the reth interface but cannot apply it on the fiber modules.<br>
<br>
show interfaces reth4 <br>
Physical interface: reth4, Enabled, Physical link is Up<br>
Interface index: 132, SNMP ifIndex: 180<br>
Link-level type: Ethernet, MTU: 9192, Speed: 1000mbps, BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled,<br>
Source filtering: Disabled, Flow control: Disabled, Minimum links needed: 1, Minimum bandwidth needed: 0<br>
Device flags : Present Running<br>
Interface flags: SNMP-Traps Internal: 0x4000<br>
Current address: 00:10:db:ff:70:04, Hardware address: 00:10:db:ff:70:04<br>
Last flapped : 2010-10-01 10:24:25 UTC (00:03:48 ago)<br>
Input rate : 264 bps (0 pps)<br>
Output rate : 480 bps (0 pps)<br>
<br>
Thanks<br>
Harris<br>
<br>
<graycol.gif></font><font size="4" color="#424282">Ben Dale ---10/01/2010 PM 02:11:40---Hi Harris</font><font size="4"><br>
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From:</font></td><td width="76%"><font size="4"><ecblank.gif></font><br>
Ben Dale <<a href="mailto:bdale@comlinx.com.au"><u><font color="#0000FF">bdale@comlinx.com.au</font></u></a>></td></tr>
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To:</font></td><td width="76%"><font size="4"><ecblank.gif></font><br>
Harris Hui/Hong Kong/IBM@IBMHK</td></tr>
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Cc:</font></td><td width="76%" valign="middle"><font size="4"><ecblank.gif></font><u><font color="#0000FF"><br>
</font></u><a href="mailto:juniper-nsp@puck.nether.net"><u><font color="#0000FF">juniper-nsp@puck.nether.net</font></u></a></td></tr>
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Date:</font></td><td width="76%"><font size="4"><ecblank.gif></font><br>
10/01/2010 PM 02:11</td></tr>
<tr valign="top"><td width="24%"><font size="4"><ecblank.gif></font><font color="#5F5F5F"><br>
Subject:</font></td><td width="76%"><font size="4"><ecblank.gif></font><br>
Re: [j-nsp] J6350 Jumbo frame MTU and OSPF setting</td></tr>
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</font><tt><font size="4"><br>
Hi Harris<br>
<br>
On 01/10/2010, at 3:35 PM, Harris Hui wrote:<br>
<br>
> I am trying to configure our J6350 fiber interface to MTU 9192 to get a<br>
> better TCP throughput. However, I can only able to configure the MTU size<br>
> below 1500, when I configure the MTU to 9192 and commit the changes, it<br>
> still shows MTU 1500 on the physical interface.<br>
<br>
I've only got a 2320 in front of me right now, but your configuration below works fine (and the MTU changes) - what version of JUNOS are you running?<br>
<br>
<br>
> Do you have any experience on using Jumbo frame MTU size on the J6350? We<br>
> are also running OSPF across the private circuit, is JUNOS support "OSPF<br>
> ignore-mtu" like cisco?<br>
<br>
No and we've been bitten by this before - I have raised an ER with my SE regarding this, but who knows how far away that will be. You shouldn't need to use it if you control the routers on both ends (and the issue you are having with MTU goes away).<br>
<br>
Cheers,<br>
<br>
Ben</font></tt><font size="4"><br>
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