[c-nsp] Ping test with DF bit and MTU / IP MTU value

[Muhammad Atif Jauhar]

Hi Simon,

Thats mean, there is any HOP in the chain not supporting the max size of the
packet I am sending, need to check with SP for this...

On Wed, Jan 19, 2011 at 12:09 PM, Thomason, Simon <
Simon.Thomason at racq.com.au> wrote:

> Hey Muhammad,
>
> If you set the MTU size to 1520 and set the DF (do not fragment bit) then
> it will tell all device to never fragment the packets... So if a single hope
> in the chain can not support the max size of the packet you are sending it
> will drop the packet.
>
> Sorry not certain if I missed something here but that seems like a simple
> enough question and answer?!?!
>
> Cheers,
>
> Simon
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:
> cisco-nsp-bounces at puck.nether.net] On Behalf Of Muhammad Atif Jauhar
> Sent: Wednesday, 19 January 2011 12:21 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Ping test with DF bit and MTU / IP MTU value
>
> Hi,
>
> I have very basic question related to MTU / IP MTU value and ping test with
> DF bit
>
> *Scenario: *
> I have one router connected to HUB router with Link leasing from SP
> *            * 1. On spoke side, we have GigaEthernet Interface with MTU
> value set to 1520
>             2. On HUB side, that link is terminated on layer-2 switch and
> from there to router sub-interface with IP MTU value set to 1520.
>             3.  Configurations on both router
> *                                 a.  SPOKE Side*
> *                                             *interface GigabitEthernet0/1
>                                             mtu 1520
>                                             bandwidth 10000
>                                             ip address 192.168.0.1
> 255.255.255.252
>                                             ip ospf network point-to-point
>                                             ip ospf cost 1000
>                                             ip ospf hello-interval 1
>                                             ip ospf dead-interval 3
>                                             ip ospf mtu-ignore
>                                             duplex auto
>                                             speed auto
>                                             mpls ip
>                                   *b. HUB Side*
> *
>                                             interface
> GigabitEthernet0/1.100
>                                             bandwidth 10000
>                                             encapsulation dot1Q 100
>                                             ip address 192.168.0.2
> 255.255.255.252
>                                             ip mtu 1520
>                                             ip ospf network point-to-point
>                                             ip ospf cost 1000
>                                             ip ospf hello-interval 1
>                                             ip ospf dead-interval 3
>                                             ip ospf mtu-ignore
>
> mpls ip
>
>
> *
> *Issue:*
>
> I am testing the link and face issue.
>                  1. while performing ping test without df bit, I am able to
> ping with size upto 18024
>                  2. while performing ping test with df bit, I am able to
> ping with size 1520
>                  3. while performing ping test with df bit, I am able to
> ping with size more than 1520
>
> *Kindly let me know, why I am not able to ping with DF bit with size more
> than 1520 (MTU value). How can I troubleshoot the issue. *
> *
> *
> *Any comment please*
> --
> Regards,
>
> Muhammad Atif Jauhar
> (+60-10-2155076)
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>


-- 
Regards,

Muhammad Atif Jauhar
(+60-10-2155076)