Cisco Cisco IOS Software Release 12.4(23) Notas de publicación
710
Caveats for Cisco IOS Release 12.4
OL-7656-15 Rev. J0
Resolved Caveats—Cisco IOS Release 12.4(5a)
Interfaces and Bridging
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CSCsc30369
Symptoms: A cBus Complex Restart may occur on a Cisco 7500 series when you leave the interface
configuration mode after you have changed the encapsulation on a serial interface from HDLC to
another encapsulation type such as PPP or Frame Relay. In addition, for interfaces with an MTU of
1500, the maximum datagram becomes fixed to 1608 for interfaces of low-speed serial port adapters
and to 1610 for interfaces of high-speed serial port adapters.
configuration mode after you have changed the encapsulation on a serial interface from HDLC to
another encapsulation type such as PPP or Frame Relay. In addition, for interfaces with an MTU of
1500, the maximum datagram becomes fixed to 1608 for interfaces of low-speed serial port adapters
and to 1610 for interfaces of high-speed serial port adapters.
Conditions: This symptom is observed after the first change to the type of encapsulation from the
default of HDLC to another encapsulation type when you leave the interface configuration mode.
Subsequent changes to the type of encapsulation do not cause the cBus Complex Restart. The
overhead added to the MTU is always 24. This will be changed to 108.
default of HDLC to another encapsulation type when you leave the interface configuration mode.
Subsequent changes to the type of encapsulation do not cause the cBus Complex Restart. The
overhead added to the MTU is always 24. This will be changed to 108.
Workaround: There is no workaround for the cBus Complex Restart. You can reconfigure the MTU
to prevent packets drop as giants.
to prevent packets drop as giants.
Further Problem Description: When the router boots with the encapsulation type set to the default
of HDLC on a serial interface, the maximum datagram size that can be accepted by the interface is
set to 1608. When the encapsulation type is changed, the maximum datagram size may change,
which causes an internal MTU change. An MTU change on a Cisco 7500 series results in a cBus
Complex Restart, which usually means a 15-second to 45-second outage on the router.
of HDLC on a serial interface, the maximum datagram size that can be accepted by the interface is
set to 1608. When the encapsulation type is changed, the maximum datagram size may change,
which causes an internal MTU change. An MTU change on a Cisco 7500 series results in a cBus
Complex Restart, which usually means a 15-second to 45-second outage on the router.
IP Routing Protocols
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CSCei93982
Symptoms: A router that is running Cisco IOS may crash unexpectedly.
Conditions: NAT must be enabled for this symptom to occur. The problem is seen when an
application uses two well known ports: one for source and the other for destination. The outgoing
translation is created, but on the return trip, using the previous source port as the destination, NAT
may use the incorrect algorithm.
application uses two well known ports: one for source and the other for destination. The outgoing
translation is created, but on the return trip, using the previous source port as the destination, NAT
may use the incorrect algorithm.
For example, if a PPTP session is initiated to the well known port 1723 from source port 21 (FTP),
then the outgoing packet will create a FTP translation (we look at source information when going
from in->out). When the packet is returned, we again look at the source information to know what
kind of packet this is. In this case we have the source port will be 1723, and NAT will assume this
is a PPTP packet. This will try to perform PPTP NAT operations on a data structure that NAT built
for a FTP packet and may lead to a crash.
then the outgoing packet will create a FTP translation (we look at source information when going
from in->out). When the packet is returned, we again look at the source information to know what
kind of packet this is. In this case we have the source port will be 1723, and NAT will assume this
is a PPTP packet. This will try to perform PPTP NAT operations on a data structure that NAT built
for a FTP packet and may lead to a crash.
Workaround: There is no workaround.
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CSCsb09709
Symptoms: A router crashes because of a watchdog timeout when you remove a BGP configuration
with an IPv6 Address Family Identifier (AFI).
with an IPv6 Address Family Identifier (AFI).
Conditions: This symptom is observed when you enter the no router bgp command for a BGP
configuration with an IPv6 AFI.
configuration with an IPv6 AFI.
Workaround: There is no workaround.
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CSCsb09852
Symptoms: The number of networks in the BGP table and the number of attributes increases, and a
slower convergence may occur for members of a BGP update group.
slower convergence may occur for members of a BGP update group.