[c-nsp] NRP2 Strange MTU Issue

Tom Williams twilliams at iasl.com
Mon Feb 6 09:45:25 EST 2006

Hi All,


I have been having a bit of an issue with an NRP2 card.  We use this
card to terminate Lan Extension service that are purchased from the
ILEC, the setup is ATM from the ILEC to us at our pop site where this
card resides, and the ILEC hands off Fast Ethernet at the remote sites.
In the past we had terminated this traffic on an NRP-1 Card and had not
issue, however when we moved the PVC to the NRP2 Card we have a problem
sending more then 1480 Byte packets over the link, where as on the NRP-1
card we could send 1500 Byte packets with no problem.   The
configuration for the interface is pasted below as are some other
details about the IOS and memory, etc.  


>From some tests I have done I can conclude that the ILEC path appears
fine since I can move it to the NRP-1 card and it works with 1500 Byte
Pings no problem.  I have also created a PVC between an NRP-1 and this
NRP-2 Card and set the MTU side to 1500 on those interfaces and I can
pass 1500 Byte pings.  


If anyone has any ideas on this it would be greatly appreciated.


----ATM Interface Paste----


interface ATM0/0/0

 no ip address

 no atm ilmi-keepalive


interface ATM0/0/0.72 point-to-point

 mtu 1500

 ip address *.*.*.* m.m.m.m

 no ip redirects

 no ip proxy-arp

 ip ospf network broadcast

 ip ospf cost 1

 ip ospf dead-interval 90

 atm route-bridged ip

 pvc TORON02CORE1 1/72

  ubr 30000




----End Paste----


----Version Details----


BOOTLDR: C6400R2SP Software (C6400R2SP-G4P5-M), Version 12.3(9d),
RE (fc2)

System returned to ROM by power-on

System restarted at 15:56:06 UTC Fri Aug 19 2005

System image file is "mir-disk0:/images/c6400r2sp-g4p5-mz"


cisco NRP2SP (NRP2SP) processor with 393216K/65536K bytes of memory.

R7000 CPU at 270MHz, Implementation 39, Rev 2.1, 256KB L2, 2048KB L3

Last reset from system control processor

X.25 software, Version 3.0.0.

Bridging software.

1 Gigabit Ethernet/IEEE 802.3 interface(s)

1 Serial network interface(s)

1 ATM network interface(s)

256K bytes of non-volatile configuration memory.





Tom Williams


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