Cisco Cisco IOS Software Release 12.0 S Release Notes
2238
Cross-Platform Release Notes for Cisco IOS Release 12.0S
OL-1617-14 Rev. Q0
Resolved Caveats—Cisco IOS Release 12.0(19)S1
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CSCdu81936
If a router receives an Address Resolution Protocol (ARP) packet that has the router’s own interface
address but with a different MAC address, the ARP packet can overwrite the router's own MAC
address in the ARP table, causing that interface to stop sending and receiving traffic. This attack is
successful only against interfaces on the Ethernet segment that is local to the attacking host.
address but with a different MAC address, the ARP packet can overwrite the router's own MAC
address in the ARP table, causing that interface to stop sending and receiving traffic. This attack is
successful only against interfaces on the Ethernet segment that is local to the attacking host.
Workaround: Hard-code the interface's ARP table entry by using the arp ip-address
hardware-address type [alias] command. This entry will remain in the ARP table until the clear arp
command is issued. see the advisory at the following URL:
hardware-address type [alias] command. This entry will remain in the ARP table until the clear arp
command is issued. see the advisory at the following URL:
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CSCdu86853
A Cisco 7500 series router that is running Cisco IOS Release 12.0 S, 12.1, 12.2, or 12.1 E with a
2-port channelized T3 port adapter (PA-MC-2T3+) may report an incorrect FREEDM version for
the second port. The FREEDM version for the first port is shown correctly, but a version number of
zero (0) is shown as the version number for the second port. There is no workaround.
2-port channelized T3 port adapter (PA-MC-2T3+) may report an incorrect FREEDM version for
the second port. The FREEDM version for the first port is shown correctly, but a version number of
zero (0) is shown as the version number for the second port. There is no workaround.
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CSCdv19356
On Cisco 12000 series Internet routers, output packet and byte counters are sometimes reported too
high on Channelized T3 and DS3 line cards when the ingress rate is higher than the egress rate (for
example, OC-3 or OC-12 in and T3 or lower out). In this situation, packets are dropped. There is no
workaround.
high on Channelized T3 and DS3 line cards when the ingress rate is higher than the egress rate (for
example, OC-3 or OC-12 in and T3 or lower out). In this situation, packets are dropped. There is no
workaround.
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CSCdv21302
On a 4xOC12 or 16xOC3 channelized ISE line card that is installed in a Cisco 12000 series Internet
router that is configured for Automatic Protection Switching (APS), after forcing a switchover via
the aps force 1 command and then reloading the protecting line card, there is no switchover back to
the working line card.
router that is configured for Automatic Protection Switching (APS), after forcing a switchover via
the aps force 1 command and then reloading the protecting line card, there is no switchover back to
the working line card.
Workaround: Force the switchover back to the working line card by entering the shutdown
command followed by the no shutdown command.
command followed by the no shutdown command.
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CSCdv24152
A Cisco router that is running Cisco IOS Release 12.0(17)S and later 12.0 S releases may reset if
Frame Relay has been incorrectly configured. If you apply the same data link control (DLC) value
on an interface and on its subinterface twice in a row, the router may reset. There is no workaround.
Frame Relay has been incorrectly configured. If you apply the same data link control (DLC) value
on an interface and on its subinterface twice in a row, the router may reset. There is no workaround.
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CSCdv25238
On a Cisco 12000 series Internet router that is running Cisco IOS Release 12.0(19)S, the router may
not forward Multiprotocol Label Switching (MPLS)-encapsulated TCP packets correctly when it
has to POP the outer label. This situation also affects User Datagram Protocol (UDP)/Internet
Control Message Protocol (ICMP)-based traffic when the packet size equals 1500 bytes. A symptom
of this condition is giant frame counter increments on the interface. There is no known workaround.
not forward Multiprotocol Label Switching (MPLS)-encapsulated TCP packets correctly when it
has to POP the outer label. This situation also affects User Datagram Protocol (UDP)/Internet
Control Message Protocol (ICMP)-based traffic when the packet size equals 1500 bytes. A symptom
of this condition is giant frame counter increments on the interface. There is no known workaround.
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CSCdv26031
The T3 controller on a 2CT3 port adapter does not come up (even if locally looped) if the controller
is receiving “loss of signal” messages. There is no workaround.
is receiving “loss of signal” messages. There is no workaround.
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CSCdv32536
When a Cisco 7200 series router that is configured with an ATM-PA-A3 port adapter receives
packets with a multicast MAC address on a virtual circuit (VC) that has been configured for
1483-bridged mode, all packets with the multicast MAC address are dropped. There is no
workaround.
packets with a multicast MAC address on a virtual circuit (VC) that has been configured for
1483-bridged mode, all packets with the multicast MAC address are dropped. There is no
workaround.