[c-nsp] 7301 (NPE-G1) leaking L2 frames over L3

[Elmar K. Bins]

Hi knowledgeable folks,

I have a somewhat weird issue with an admittedly slightly aged IOS
on a 7301: That router is leaking Ethernet frames from one L3 interface
to another.

I have been alerted by the folks at the exchange (who monitor very
closely, thanks). Since they haven't turned my port off yet,
leaking should be minimal.

The box is a 7301 with PA-2FE-TX (f1/0 connected to the exchange),
running IOS 12.3(14)T7.

Inside - towards some servers - is a L3 portchannel
(via a WS-3750):

interface Port-channel1
 description PO to sw (via g0/0 and g0/1)
 ip address xxx.xxx.xxx.1 255.255.255.0
 ip access-group MGT-no in
 ip access-group acl-SERVICE-out out
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip route-cache same-interface
 ip route-cache flow
 load-interval 30
 duplex full
 hold-queue 150 in
end


Outside is a layer 3 port to the exchange fabric:

interface FastEthernet1/0
 description exchange port
 ip address xxx.xxx.xxx.xxx 255.255.254.0
 ip access-group FILTER_IN-FastEthernet1-0-in-3 in
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 ip accounting mac-address input
 ip accounting mac-address output
 ip accounting access-violations
 load-interval 30
 duplex full
 speed 100
 ipv6 address xx:xx:xx:xx:xx:xx:xx:xx/64
 ipv6 nd suppress-ra
 no ipv6 mld router
 no keepalive
 no cdp enable
end


Captured frames show that Ethernet frames with source MACs
of the server NICs make it to the exchange fabric somehow.

My questions:

  - is this some kind of misconfiguration on my part?
  - if not: does anyone know of / remember such a bug?
  - how could I find info, probably on cisco.com?
  
I'm at a loss here. Blindly upgrading to T14 or whatever
might or might not kill the bug. I'd like to reboot as
rarely as possible...

Thanks for any help, hints or insight.

Elmar.