Network connectivity between clients and servers
may not work after the installation of security update
KB893066 or
Windows Server 2003 Service Pack 1
Network connectivity between clients
and servers may fail. This failure occurs after the installation of
either security update MS05-019 or Microsoft Windows Server 2003
Service Pack 1 (SP1). Any one or more of the following symptoms may
occur:
#
Inability to connect to terminal servers or to file share access.
#
Failure of domain controller replication across WAN links. #
Microsoft Exchange servers cannot connect to domain controllers.
These symptoms are more likely to occur in WAN and LAN
configurations and scenarios. These configurations and scenarios
typically exist where routers and data-link level protocols that
have different Maximum Transmission Units (MTUs) are used across the
network. In this scenario, the sending host can receive several
Internet Control Message Protocol (ICMP) destination unreachable
messages that have MTU updates for a destination. These symptoms are
most likely to occur if the following conditions are true:
1. During the PathMTUDiscovery process several routers on the
route to the destination send MTU updates to the source host. One of
the possible reasons for this could be that source and destination
hosts are in different WAN segments. Additionally, these segments
are connected through a tunnel with a small MTU.
2. Network load balancing, dynamic routing, or both are used.
In this scenario, there are several possible routes to a destination
that has MTUs that are different from the MTU of the sending subnet
and that are different from each other. Therefore, changing the
route of IP packets over time can produce several MTU updates for
the destination address.
Note There may be some other similar scenarios and network
configurations where these symptoms occur. These scenarios can
typically be diagnosed by sniffing the network traffic on either the
source host side or on one of the intermediate network routers. If
there are multiple ICMP destination unreachable messages sent over
time for a destination, the source host that has the
MS05-019 security update or Windows Server 2003 SP1 installed is
likely to have this problem.
KB898060
- The Cause Of Problems
This problem occurs because the code incorrectly increments the
number of host routes on the computer when the code modifies the MTU
size of a host route. The maximum number of host routes is
controlled by the Registry Value in MaxIcmpHostRoutes. The
default number of host routes is 1,000. Because of the incorrect
increment, the number of host routes eventually reaches the maximum
value. After the maximum value is reached, the ICMP packets are
ignored.
KB898060 - Hot Fix
A supported hotfix is now available from Microsoft, but it is only
intended to correct the problem that is described in this article. Only
apply it to systems that are experiencing this specific problem. This
hotfix may receive additional testing. Therefore, if you are not
severely affected by this problem, we recommend that you wait for the
next service pack that contains this hotfix.
To resolve this problem immediately, contact Microsoft Product Support
Services to obtain the hotfix. For a complete list of Microsoft Product
Support Services phone numbers and information about support costs,
visit the following Microsoft Web site:
Note In special cases, charges that are ordinarily incurred for
support calls may be cancelled if a Microsoft Support Professional
determines that a specific update will resolve your problem. The usual
support costs will apply to additional support questions and issues that
do not qualify for the specific update in question.
HOWEVER a quick work around this
problem is to set the default MTU size to the largest size that
the routers can process. The actual MTU value that is required to work
around this problem depends on the network configuration. However, an
MTU value of 576 should help reduce the effect of the problem
because routers on the Internet should be able to handle such packets
without fragmentation.
Important Setting a low default MTU value can slow down the
network performance.
Marc Liron -
Bio
Microsoft Digital Media MVP
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