Hi All,
We're experiencing a strange situation on a 3750G PoE switch running advanced IP Services featureset whereby frames switched solely at layer 2 (e.g. between IPv6 hosts within the same vlan), but as soon as the frame is forwarded at layer3 through the routed vlan interface, it drops 5% of packets at VERY regular intervals (not random, almost as if it's a timing or buffering issue). Doing an extended ipv6 ping from the switch itself to a directly attached host we can see this effect clearly as in the following output:
This host is directly connected to the switch and the switch is the default gateway for the vlan itself.
wg-sw1-dc1#ping ipv6
Target IPv6 address: 26XX:XXXX:XXXX:XXXX::XXXX
Repeat count [5]: 500
Datagram size [100]:
Timeout in seconds [2]:
Extended commands? [no]:
Type escape sequence to abort.
Sending 500, 100-byte ICMP Echos to 26XX:XXXX:XXXX:XXXX::XXXX, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!
!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!
!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!
!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!
!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!.
!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!
!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!
!!!!!!!!!!
Success rate is 95 percent (478/500), round-trip min/avg/max = 0/1/26 ms
However, between the switch and an uplink routed interface (physical, not logical vlan interface), there is no packet loss at all.
wg-sw1-dc1#ping ipv6
Target IPv6 address: 26XX:XXXX:YY::ZZ
Repeat count [5]: 500
Datagram size [100]:
Timeout in seconds [2]:
Extended commands? [no]:
Type escape sequence to abort.
Sending 500, 100-byte ICMP Echos to 26XX:XXXX:YY::ZZ, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!
Success rate is 100 percent (500/500), round-trip min/avg/max = 0/2/33 ms
The SDM profile is set to desktop dual ipv4-ipv6 routing. IOS version is 12.2(55)SE advanced IP Services.
The problem appears to only occur when fowarding to/from one of the VLAN virtual routed interfaces... additionally, this is only occuring on the 3750G PoE -- there is no problem on any of our other production platforms (ranging from 3560, to 3750G [non-PoE], to 6500 with VSS1440).
Anyone happen to have come across anything similar and if so, what work arounds did you find, if any?
Thanks in advance,
Leland
