01-09-2009 09:50 AM - edited 03-06-2019 03:21 AM
Hi to all,
I have an etherchannel using 4 gigabit interfaces and i'm having high utilization just in one of it. It's the interface G6/32 on the SW-CENTRAL1 and SW-CENTRAL2 the ones that are having this situation (one in output and the other in input), the etherchannel is configured as desirable between two WS-C4507R with the IOS version 12.2(20)EWA4.
The configurations for the etherchannel are exactly the same for the two devices:
interface Port-channel2
description PortChannel-Central
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
interface GigabitEthernet6/29
description EtherChannel-2
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 2 mode desirable
!
interface GigabitEthernet6/30
description EtherChannel-2
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 2 mode desirable
!
interface GigabitEthernet6/31
description EtherChannel-2
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 2 mode desirable
!
interface GigabitEthernet6/32
description EtherChannel-2
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 2 mode desirable
SW-CENTRAL1#sh int port-channel 2
Port-channel2 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 000e.84cd.306e (bia 000e.84cd.306e)
Description: PortChannel-Central
MTU 1500 bytes, BW 4000000 Kbit, DLY 10 usec,
reliability 255/255, txload 7/255, rxload 6/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is N/A
input flow-control is off, output flow-control is unsupported
Members in this channel: Gi6/29 Gi6/30 Gi6/31 Gi6/32
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output never, output hang never
5 minute input rate 99376000 bits/sec, 20421 packets/sec
5 minute output rate 112217000 bits/sec, 20172 packets/sec
SW-CENTRAL2#sh int port-channel 2
Port-channel2 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 000e.84cd.2cde (bia 000e.84cd.2cde)
Description: PortChannel-Central
MTU 1500 bytes, BW 4000000 Kbit, DLY 10 usec,
reliability 255/255, txload 6/255, rxload 6/255
Full-duplex, 1000Mb/s, media type is N/A
input flow-control is off, output flow-control is unsupported
Members in this channel: Gi6/29 Gi6/30 Gi6/31 Gi6/32
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output never, output hang never
Last clearing of "show interface" counters 11w0d
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 108971000 bits/sec, 19845 packets/sec
5 minute output rate 102179000 bits/sec, 20525 packets/sec
Do you know what could be causing this??
Thanks in advance for your help.
01-09-2009 09:57 AM
Alfonso
Any one individual conversation will always use the same link. How the individual conversations are defined is down to the load-balancing algorithm in use on the switch.
So it may just be that 2 machines on either side of the link are doing all the talking at the moment or it may be that your load-balancing algorithm could be changed to get a better distribution across the links. Have a look at this doc for more details on etherchannel load-balancing -
http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml
Jon
01-09-2009 10:00 AM
What EtherChannel load-balancing algorithm are you using? Depending on the traffic characteristics it is possible this behaviour is normal.
Have a read of the EtherChannel chapter here:
http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/50sg/configuration/guide/channel.html
HTH
Andy
01-09-2009 12:27 PM
From the output you've showed, how are you verifying that it's only using one link?
01-09-2009 12:32 PM
Hi,
My LMS is sending me this message:
EVENT ID = 0008HOB
ALERT ID = 00001L8
TIME = Thu 08-Jan-2009 04:54:10 CST
STATUS = Active
SEVERITY = Critical
MANAGED OBJECT = 128.127.254.1
MANAGED OBJECT TYPE = Switches and Hubs
EVENT DESCRIPTION = HighUtilization::Component=PORT-128.127.254.1/95 [Gi6/32] [EtherChannel-2];OutputPacketRate=67309.25 PPS;Type=ETHERNETCSMACD;CurrentUtilization=75.16374 %;InputPacketRate=16970.86 PPS;TrafficRate=9.395468E7 BYPS;UtilizationThreshold=75;DuplexMode=FULLDUPLEX;MaxSpeed=1000000000;
CUSTOMER IDENTIFICATION = Switches
And i also graph the traffic on all the etherchannel interfaces and is just the g6/32 the one that is having this high utilization
01-09-2009 12:58 PM
Because of the channel distribution method that is configured looks like most is riding that single link , you need to figure out why. Are all the links up in the channel group ? Post a "show ether summary " command.
01-09-2009 01:05 PM
Hi Glen,
Here is the output from the 2 sw:
SW-CENTRAL1#sh etherchannel summary
Number of channel-groups in use: 2
Number of aggregators: 2
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
2 Po2(SU) PAgP Gi6/29(P) Gi6/30(P) Gi6/31(P)
Gi6/32(P)
4 Po4(SU) - Gi7/3(P) Gi7/4(P)
SW-CENTRAL2#sh etherchannel summary
Number of channel-groups in use: 2
Number of aggregators: 2
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
2 Po2(SU) PAgP Gi6/29(P) Gi6/30(P) Gi6/31(P)
Gi6/32(P)
3 Po3(SU) - Gi7/1(P) Gi7/2(P)
I don't know why most of the traffic is going only throught this single port, one thing important is that this happens on a random period of time, i mean the g6/32 is not all the time with high utilization.
Thanks
01-09-2009 01:16 PM
Hello Alfonso,
use
sh etherchannel load-balance
to see what algorythm is in use
example:
sh etherchannel load-balance
EtherChannel Load-Balancing Configuration:
src-dst-ip
mpls label-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
MPLS: Label or IP
Hope to help
Giuseppe
01-09-2009 01:11 PM
I agree.
Use the option that provides the balance criteria with the greatest variety in your configuration. For example, if the traffic on an EtherChannel is going only to a single MAC address and you use the destination MAC address as the basis of EtherChannel load balancing, the EtherChannel always chooses the same link in the EtherChannel; using source addresses or IP addresses might result in better load balancing.
For more details on configuring channel laod-balancing:
01-09-2009 01:24 PM
Hi,
I'll try that.
Thanks to all for your help.
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