troubleshooting Question

Etherchannel load balancing not working properly

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myriadsupply asked on
NetworkingRoutersSwitches / Hubs
3 Comments2 Solutions2620 ViewsLast Modified:
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

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