VM66406: PEVM66302 INTERMITTENT PKT LOSS ON VSWITCH IP ROUTER

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• After applying VM66302 on a system with an IP Layer VSWITCH
  the PRIROUTER guest experienced intermittent packet loss.
  
  The packets affected were inbound packets with an IP address
  that was NOT registered to any virtual NIC coupled to the
  VSWITCH (e.g. IP destination 10.0.0.1 for a VSWITCH with
  interfaces that registered IP addresses on the 192.168.0.0/24
  subnet.  These inbound packets should have been delivered to
  the virtual router guest that had enabled "primary_router"
  mode.  When a series of packets for the unregistered address
  (e.g. 10.0.0.1) entered the VSWITCH, the first packet was
  delivered and subsequent packets for the same address were
  discarded.
  
  The virtual router supported 10.0.0.1 but did not register
  that IP address on this VSWITCH. TRSOURCE data confirmed that
  an inbound packet with a destination of 10.0.0.1 was delivered
  to the virtual router (and solicited a reply) but the next one
  (or more) inbound packet(s) with the same destination were
  dropped (and counted as RX Discards on the RDEV interface).
  
  This was a configuration that was working before applying
  service.
  

Local fix

• Apply PTF
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Virtual routers in a PRIROUTER or SECROUTER  *
  *                 VSWITCH may experience intermittent packet   *
  *                 loss after applying APAR VM66302.            *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  Virtual routers (VM users with the virtual NIC configured to
  enable primary router mode or secondary router mode) within a
  VSWITCH may experience intermittent packet loss. Packets that
  enter the OSA RDEV interface for a destination that is not
  explicitly registered to a virtual NIC should be delivered to
  the virtual NIC registered as the primary router (or secondary
  router). This works for the first NEW packet for a given
  destination, but fails for subsequent packets because the
  destination for a UNICAST router was cached as a list, and the
  code segment processing a repeat unicast address was expecting a
  single device pointer to be cached. Subsequent packets that
  should have used the same router list were discarded until a
  packet entered for a new destination (wiping out the old cache).
  

Problem conclusion

• The logic in HCPVNSDG to handle a unicast router (primary router
  or secondary router) is revised to clearly indicate that the
  router list is stored in the source NIDLLX01 field and the
  normal unicast target device address is stored in the source
  NIDDXNID field. Meanwhile, the logic in HCPVNSDG that detects a
  repeated destination by IP address and VLAN is updated to test
  for a unicast list first (NIDLLX01) and only use NIDDXNID if
  there is no unicast router list.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UM35707 UM35708

Modules/Macros

• HCPLAN   HCPVNS
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R710 PSY UM35707

     UP20/08/19 P 2101 {

• R720 PSY UM35708

     UP20/08/19 P 2101 {

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.