[j-nsp] J6350 Jumbo frame MTU and OSPF setting

[Harris Hui]

Hi Ben,

Looks like I can apply the MTU setting on the reth interface but cannot
apply it on the fiber modules.

show interfaces reth4
Physical interface: reth4, Enabled, Physical link is Up
  Interface index: 132, SNMP ifIndex: 180
  Link-level type: Ethernet, MTU: 9192, Speed: 1000mbps, BPDU Error: None,
MAC-REWRITE Error: None, Loopback: Disabled,
  Source filtering: Disabled, Flow control: Disabled, Minimum links needed:
1, Minimum bandwidth needed: 0
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x4000
  Current address: 00:10:db:ff:70:04, Hardware address: 00:10:db:ff:70:04
  Last flapped   : 2010-10-01 10:24:25 UTC (00:03:48 ago)
  Input rate     : 264 bps (0 pps)
  Output rate    : 480 bps (0 pps)

Thanks
Harris


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  |Ben Dale <bdale at comlinx.com.au>                                                                                                                   |
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  |Harris Hui/Hong Kong/IBM at IBMHK                                                                                                                    |
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  |juniper-nsp at puck.nether.net                                                                                                                       |
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| Date:      |
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  |10/01/2010 PM 02:11                                                                                                                               |
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  |Re: [j-nsp] J6350 Jumbo frame MTU and OSPF setting                                                                                                |
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Hi Harris

On 01/10/2010, at 3:35 PM, Harris Hui wrote:

> I am trying to configure our J6350 fiber interface to MTU 9192 to get a
> better TCP throughput. However, I can only able to configure the MTU size
> below 1500, when I configure the MTU to 9192 and commit the changes, it
> still shows MTU 1500 on the physical interface.

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?


> Do you have any experience on using Jumbo frame MTU size on the J6350? We
> are also running OSPF across the private circuit, is JUNOS support "OSPF
> ignore-mtu" like cisco?

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).

Cheers,

Ben
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