[j-nsp] Big Size Packets on DS3

[Lars Erik Gullerud]

On Wed, 2003-12-03 at 16:58, Kashif.Khawaja at Broadwing.com wrote:

> > Since  the  default  MTU is 4474 you know where the default 
> > limit is  and  if  you  want to send bigger mtu size packets 
> > what about increasing the MTU size ?
> > 
> > josefb at M10-xxx> show interfaces t3-1/1/0
> > Physical interface: t3-1/1/0, Enabled, Physical link is Down
> >   Interface index: 132, SNMP ifIndex: 23
> >   Link-level type: PPP, MTU: 4474, Clocking: Internal, Speed: T3,
> 
> trying to get to the default MTU. Getting bogged down at about 4445 bytes. Tried another
> channel on this CHOC-12 to no avail. The exact same setup works fine when tried with
> Cisco.

Keep in mind that if you use the "size" parameter on the juniper ping
command to test what you are describing, it only counts the payload, not
the IP or ICMP headers, so the maximum size you can ping with is your
inet mtu (4470) - 28 bytes = 4442. So this is normal behaviour. You can
see the same thing on an Ethernet interface with standard inet mtu of
1500, where 1472 is the largest size parameter to junipers ping you will
get through the link with do-not-fragment set.

/leg