[c-nsp] Uneven LACP load-balancing

[Brandon Ewing]

I've got a weird problem that I hope someone can shed some light on.  We
have multiple 3560G's deployed currently, each utilizing 4 SFP's for uplink.
The switches are configured with 2 L2 port-channels, with a different SVI in
each port-channel pointing to our upstream router.  IE:

g0/49 + g0/51 to core A, carries Vlan 100
g0/50 + g0/52 to core B, carries Vlan 200

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
4      Po4(SU)         LACP      Gi0/49(P)   Gi0/51(P)
5      Po5(SU)         LACP      Gi0/50(P)   Gi0/52(P)


We have two default routes, pointing out the above vlans:
switch#show ip cef 0.0.0.0 0.0.0.0
0.0.0.0/0
  nexthop 10.10.1.241 Vlan200
  nexthop 10.10.1.245 Vlan100

The etherchannel load-balancing method is set to src-dst-ip:
switch#show etherc load-balance
EtherChannel Load-Balancing Configuration:
        src-dst-ip

EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source XOR Destination MAC address
  IPv4: Source XOR Destination IP address
  IPv6: Source XOR Destination IP address


However, we are not seeing an even distribution of traffic among the 4
ports -- each L2 etherchannel is trasmitting on only one port:
switch#show control util
Port       Receive Utilization  Transmit Utilization
Gi0/49             1                    55
Gi0/50             6                    0
Gi0/51             1                    0
Gi0/52             12                   57

Examination of flowstats from the core on the uplink interfaces shows a good
mix of src/dst IPs -- so why am I getting the polarization?

Additionally, examining a test flow with the command line shows that it
SHOULD be working, but it's not:

switch#show ip cef exact-route 172.16.79.186 192.168.42.183
172.16.79.186 -> 192.168.42.183 => IP adj out of Vlan100, addr 10.10.1.245

switch#test etherchannel load-balance interface po4 ip 172.16.79.186 192.168.42.183
Would select Gi0/51 of Po4

However, g0/51 has no traffic on it, and hasn't for some time.  Can anyone
provide some clue?  This is occuring on multiple switches, and all switches
are running 12.2(50)SE1 ip services

-- 
Brandon Ewing                                        (nicotine at warningg.com)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
URL: <https://puck.nether.net/pipermail/cisco-nsp/attachments/20101110/f7d9a5f5/attachment.bin>