MPROUTE LOOPS TRYING TO INITIALIZE
APAR Identifier ...... PK25441 Last Changed ........ 06/10/06
MPROUTE LOOPS TRYING TO INITIALIZE
Symptom ...... LP LOOP Status ........... CLOSED PER
Severity ................... 2 Date Closed ......... 06/07/25
Component .......... 5735FAL00 Duplicate of ........
Reported Release ......... 520 Fixed Release ............ 999
Component Name TCP/IP V2 FOR V Special Notice
Current Target Date .. Flags
SCP ...................
Platform ............
Status Detail: SHIPMENT - Packaged solution is available for
shipment.
PE PTF List:
PTF List:
Release 520 : UK16599 available 06/07/31 (0602 )
Parent APAR:
Child APAR list:
ERROR DESCRIPTION:
MPROUTE initializes and goes into a CPU utilzation state. Traces
indicate that MPROUTE is looping trying to send bad DATA
Descriptor packets. A VMDUMP indicates that a bad MTU (0) was
set incorrectly causing the problem to occur.
LOCAL FIX:
Change MTU= 0 statement in the MPROUTE CONFIG file to the
correct value being used.
PROBLEM SUMMARY:
****************************************************************
* USERS AFFECTED: ALL USERS OF MPROUTE. *
****************************************************************
* PROBLEM DESCRIPTION: *
****************************************************************
* RECOMMENDATION: APPLY PTF *
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When a user codes MTU=0, MPROUTE updates the interface control
block MTU field with the value from the LINK statement in the
TCPIP configuration. However, another field in the OSPF
interface control block, which represents the maximum OSPF
packet size and is based off the value of the MTU fails to
get updated at the same time. This results in the interface
control block having the correct MTU while the OSPF interface
control block has a value of zero for the maximum packet size.
When this problem occurs, neighbors will be stuck in state 32
with at least 1 outstanding LSA on the database summary list.
The MPROUTE trace will show MPROUTE enter state 32 and then
show the sending and receiving of empty database exchange
packets with the database exchange packet from MPROUTE having
the M bit set.
PROBLEM CONCLUSION:
The routine MPRGMTU, that sets the interface MTU from the LINK
statement, was changed to also set the maximum OSPF packet size.
THE FOLLOWING CHANGES HAVE BEEN MADE TO THE SYSTEM REFERENCE
LIBRARIES:
***START PUBLICATION CHANGE*************************************
PUBLICATION TITLE: z/VM V5R2.0 TCP/IP Messages and Codes
RELEASE: V5R2.0
ORDER NUMBER: GC24-6124-01
-------------------------------------------
CHAPTER: 6 MPROUTE Messages
ABSTRACT: Add the message DTCMPR8097I
DTCMPR8097I MTU value of <mtu> was coded for interface
<interface>. Default MTU of 576 will be used.
Explanation: An invalid maximum transmission unit (MTU) was
specified on the OSPF_INTERFACE, RIP_INTERFACE or INTERFACE
statement in the MPROUTE CONFIG file, and the MTU was not
specified on the corresponding LINK statement in the PROFILE
TCPIP. The MTU value in the MPROUTE CONFIG file must be a
number from 576 to 65535 (but cannot exceed the value
specified on the LARGEENVELOPEPOOLSIZE statement), or the
MTU value can be zero if the MTU is specified on the LINK
statement.
System Action: MPRoute uses the default MTU of 576 and
continues.
System Programmer Response: Specify a valid MTU value on the
OSPF_INTERFACE, RIP_INTERFACE or INTERFACE statement in the
MPROUTE CONFIG file, or specify an MTU of zero on the
OSPF_INTERFACE, RIP_INTERFACE or INTERFACE statement in the
MPROUTE CONFIG file and specify an MTU on the corresponding
LINK statement in the PROFILE TCPIP.
***END PUBLICATION CHANGE***************************************
TEMPORARY FIX:
COMMENTS:
MODULES/MACROS: MPRGMTU MPRIFOPN MPROUTE MSMPROUT
SRLS: GC24612401
RTN CODES:
CIRCUMVENTION:
MESSAGE TO SUBMITTER: