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

[Harris Hui]

Hi Ben,

Thanks for your reply. I am using JUNOS 10.0R4.7.

harris@> show version
node0:
--------------------------------------------------------------------------
Hostname:
Model: j6350
JUNOS Software Release [10.0R4.7]

node1:
--------------------------------------------------------------------------
Hostname:
Model: j6350
JUNOS Software Release [10.0R4.7]

{primary:node0}


For the OSPF setting, do you mean that if I am using the same MTU values
eg. 9192 on both Routers, it should be fine without telling the OSPF to
ignore the MTU value?

However, I am also running OSPF on several secure-tunnel interfaces (st0.0
and st0.1), I have to configure the MTU value to 1500 on those
secure-tunnel logical unit in order to form a FULL state of OSPF neighbour
with the peers.




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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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