Connectivity Problems When Using VARSUBNETTING
And MPROUTE
APAR Identifier ...... PQ51454 Last Changed ........ 01/11/02
CONNECTIVITY PROBLEMS WHEN USING VARSUBNETTING AND MPROUTE
Symptom ...... IN INCORROUT Status ........... CLOSED PER
Severity ................... 1 Date Closed ......... 01/09/06
Component .......... 5735FAL00 Duplicate of ........
Reported Release ......... 3A0 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 3A0 : UQ57563 available 01/09/13 (1000 )
Release 320 : UQ57564 available 01/09/13 (1000 )
Release 410 : UQ57565 available 01/09/13 (1000 )
Parent APAR:
Child APAR list:
ERROR DESCRIPTION:
Customer has an OSA-device connected network. Hosts on this
network cannot reach other hosts that are connected to the VM
host via a point-to-point connections.
From reviewing the TCP/IP server configuration file, it's
seen that VIPA and VARSUBNETTING support are in use, in
conjunction with the MPROUTE server (running OSPF).
A NETSTAT GATEWAY command shows that correct point-to-point
pathways are established, and connectivity exists between the
VM host and its peers for these connections. However, hosts
on the OSA-connected network experiences timeouts.
Tracing shows that IPUP perceives the addresses for hosts on
the OSA-connected network to be broadcast addresses:
DTCIPU040I IP-up: forward datagram
DTCIPU041I IP-up: discard broadcast packet
LOCAL FIX:
PROBLEM SUMMARY:
****************************************************************
* USERS AFFECTED: All VM TCP/IP users *
****************************************************************
* PROBLEM DESCRIPTION: Connectivity problems when remote *
* hosts try to connect thru VM TCP/IP *
* to other remote hosts. *
****************************************************************
* RECOMMENDATION: APPLY PTF *
****************************************************************
When UpToIp (in TCIPUP) is processing inbound packets, it
calls IsBroadcast to determine if the packet is a broadcast.
The IsBroadcast function is using the BsdSubnetMask from
WhichLink (the link the packet arrived on), and incorrectly
flagging some packets as broadcast packets. UpToIp is
discarding them, which causes connectivity failures.
PROBLEM CONCLUSION:
The IsBroadCast function has been changed to call GetNetInfo
to determine the route for the incoming address. The routing
information found (including subnet mask) is then used to
determine if this address is a broadcast address.
TEMPORARY FIX:
COMMENTS:
MODULES/MACROS: TCIPUP TCPIP
SRLS: NONE
RTN CODES:
CIRCUMVENTION:
MESSAGE TO SUBMITTER:
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