Sg300-28 port-channel options

Question

i have an sg300-28 running the latest firmware, and would like some insight on port-channel options.  below are the port configs i have for a LAG to my router.  i am currently using 802.3ad with LACP.  my router is a linux machine pulling duty as a basic (no dynamic routing) router, firewall and internet gateway.  the bonding options on the routers side explained at
http://docs.fedoraproject.org/en-US/Fedora/16/html/System_Administrators_Guide/sec-Using_Channel_Bonding.html.  the mode is 4 or 802.3ad and the xmit_hash_policy is 2 or layer2+3.  i also have 2 servers setup in a similar fashion with 2 interfaces in a LAG.
when i run a bandwidth test, iperf, between the two servers, i only get 900+ mbps which indicates that the GB ports are running fine.  this also indicates to me that the traffic is not being "striped" across the port-channeled interfaces, thereby giving me the aggregated bandwidth of all interfaces in the LAG.  i have found no options to use the balance-xor mode to create port-channels, which as i understand it, would aggregate the total bandwidth of all interfaces in the LAG.  is the sg300 capable of creating a LAG that will combine the throughput of all the members of the LAG?  for example, create a 2 GB pipe when 2 interfaces are port-channeled?  is the balance-xor mode what would do this (regardless of the sg300's ability to do this)
interface gigabitethernet25
description "Port Channel to Router"                
channel-group 1 mode auto
lldp notifications enable
lldp optional-tlv port-desc sys-name sys-desc sys-cap 802.3-mac-phy 802.3-lag 802.3-max-frame-size
lldp management-address automatic
interface gigabitethernet26
description "Port Channel to Router"
channel-group 1 mode auto
lldp notifications enable
lldp optional-tlv port-desc sys-name sys-desc sys-cap 802.3-mac-phy 802.3-lag 802.3-max-frame-size
lldp management-address automatic
interface gigabitethernet27
description "Port Channel to Router"
channel-group 1 mode auto
lldp notifications enable
lldp optional-tlv port-desc sys-name sys-desc sys-cap 802.3-mac-phy 802.3-lag 802.3-max-frame-size
lldp management-address automatic
interface gigabitethernet28
description "Port Channel to Router"
channel-group 1 mode auto                           
lldp notifications enable
lldp optional-tlv port-desc sys-name sys-desc sys-cap 802.3-mac-phy 802.3-lag 802.3-max-frame-size
lldp management-address automatic
interface Port-channel1
description "Port Channel to Router"
switchport mode general
switchport general allowed vlan add 2-3,25,37,50,52,253-255 tagged
switchport general pvid 255

Answer 1

Hi Brendan,
You said "i only get 900+ mbps which indicates that the GB ports are running fine.  this also indicates to me that the traffic is not being "striped" across the port-channeled interfaces, thereby giving me the aggregated bandwidth of all interfaces in the LAG.  i have found no options to use the balance-xor mode to create port-channels, which as i understand it, would aggregate the total bandwidth of all interfaces in the LAG."
As the Admin guide says on page 130, http://www.cisco.com/en/US/docs/switches/lan/csbms/sf30x_sg30x/administration_guide/78-19308-01.pdf
Load Balancing
Traffic forwarded to a LAG is load-balanced across the active member ports, thus achieving an effective bandwidth close to the aggregate bandwidth of all the active member ports of the LAG.
Traffic load balancing over the active member ports of a LAG is managed by a hash-based distribution function that distributes Unicast and Multicast traffic based on Layer 2 or Layer 3 packet header information.
The switch supports two modes of load balancing:
By MAC Addresses—Based on the destination and source MAC addresses of all packets.
By IP and MAC Addresses—Based on the destination and source IP addresses for IP packets, and destination and source MAC addresses for
non-IP packets.
   So,  an IP host running running IPERF maybe checking unicast throughput between the two IP hosts.  There will be a Source and Desination IP address in that test.  The switch will direct the traffic over one of the LAG port members .  It wont Round robin the unicast traffic over multiple LAG ports, if the Source and Desination IP address of the traffic is the same.  .
If the  PC  running IPerf,  had  another concurrent IPerf session to another or different IP host, the hash algorithm on the switch may direct that stream , maybe, over a different physical LAG interface.
So your comment about  achieving  900+mbps  sounds normal   Yes LAG spreads the load, the benefit comes when lots of hosts on  both sides of the switches.
You hay find with just two hosts on either side of a LAG, that the switch may run the traffic between two hosts over just one member of the LAG group.
regards Dave