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HP 2848 LACP Trunking - no Load Balancing

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MarkusBurggraf
Occasional Contributor

HP 2848 LACP Trunking - no Load Balancing

Hi,

 

I have 2 switches trunked with LACP, both HP 2848 (J4904A).

Connection between the Switches is a LACP Trunk of 4 Ports.

 

Running Configuration Switch 1:

trk 41-44 TRK10 LACP

vlan 100

   name "INTERNAL"

   untagged 33-37,40,Trk1-Trk4,Trk11

   ip address 172.16.96.10 255.255.224.0

   tagged 1-4,Trk10

   exit

vlan 230

   name "CLUSTER"

   untagged 25-31

   tagged Trk10

   exit

vlan 240

   name "ISCSI-UNUSED"

   tagged Trk10

   exit

vlan 250

   name "ISCSI1"

   tagged 1-4,Trk10

   jumbo

   exit

vlan 260

   name "MIGR"

   tagged Trk10

   exit

vlan 270

   name "ISCSI2"

   tagged 1-4,Trk10

   jumbo

   exit

spanning-tree Trk10 priority 4

 

Running Configuration Switch 2:

trunk 41-44 Trk10 LACP

vlan 230
name "CLUSTER"
tagged Trk10
exit
vlan 260
name "MIGR"
untagged 9-12
tagged Trk10
exit
vlan 240
name "ISCSI-UNUSED"
untagged 29-34
tagged Trk10
exit
vlan 250
name "ISCSI1"
untagged 17-22
tagged 1-4,Trk10
jumbo
exit
vlan 270
name "ISCSI2"
untagged 23-28
tagged 1-4,Trk10
jumbo
exit
vlan 100
name "INTERNAL"
untagged 13-14,39-40
ip address 172.16.96.11 255.255.224.0
tagged 1-4,Trk10

 

The trunk works but there is no load balancing, only 1 Port is used (about 30-40% average load and the other Ports transmit about 100000 Packages a day.

 

I thought that there is some round-robin like load balancing mechanism that should ditribute the traffic.

 

Am I missing something or is the configuration wrong somehow?

 

Best regards

Markus 

2 REPLIES
Richard Brodie_1
Honored Contributor
Solution

Re: HP 2848 LACP Trunking - no Load Balancing

Round-robin load balancing is non-standard for LACP. The problem is that it allows packets to be delivered out of order, and not all protocols can cope with that. Even when they do, it's variable whether receiving protocols from a single stream on different NICs and reassembling is much of a win or not.

 

The usual load balancing method is taking source-address/destination address pairs and hashing them between the ports. If your LACP link is between two switches in a big flat network, load balancing will work well. The worst case is where you have a stub IP link betwen two routers where all the unicast traffic will be on one pair. It sounds like you have something like the worst case.
 

More modern switches might give you more load balancing options. Looking at the newest Procurve, the 3800 it supports hashing on  IP addresses, and even down to TCP and UDP ports. I couldn't  see anything in the 2848 documentation that suggests other than MAC source-address/destination address pairs.

MarkusBurggraf
Occasional Contributor

Re: HP 2848 LACP Trunking - no Load Balancing

Thanks for your answer. It seems that you are right.