APA: traffic only through one NIC in two-NIC aggregate

[David Markus]

Hi all,

we have a server where the backend network is setup as trunk of 2 NICs (lan1 and lan4), in FEC_AUTO mode and LB_MAC as loadbalancing method.

We noticed that 99% of the traffic goes through lan1 and almost nothing through lan4.

The ports on the switch (Cisco 6509) are setup correctly as a PAgP link.

I've checked the config files on the system and as far as I can see everything seems to be fine.

I do notice that most outbound traffic is towards two NFS servers.

What can I do to make more use of lan4, as the customer is about to increase the load (and traffic) on the server?

Thanks :)

David

--- info:
HP-UX B.11.11
9000/800/SD64000
J4240AA B.11.11.20 Auto-Port Aggregation Software

hp_apaconf:
HP_APA_INTERFACE_NAME[0]=lan900
HP_APA_LOAD_BALANCE_MODE[0]=LB_MAC
HP_APA_HOT_STANDBY[0]=off
HP_APA_GROUP_CAPABILITY[0]=900
HP_APA_KEY[0]=

hp_apaportconf:
HP_APAPORT_INTERFACE_NAME[0]=lan1
HP_APAPORT_GROUP_CAPABILITY[0]=900
HP_APAPORT_CONFIG_MODE[0]=FEC_AUTO

HP_APAPORT_INTERFACE_NAME[1]=lan4
HP_APAPORT_GROUP_CAPABILITY[1]=900
HP_APAPORT_CONFIG_MODE[1]=FEC_AUTO

lanadmin -x -i 900
Link Aggregate PPA # : 900
Link Aggregation Mode : FEC_AUTO
Load Balance Mode : MAC Address based (LB_MAC)
Active Ports PPA # : 1 4
Port(s) not ready : NONE

lanadmin -s -m 900
MTU Size = 1500
Speed = 2000000000

lanadmin -g 1 excerpt:
PPA Number = 1
Station Address = 0x12799e3da4
Administration Status (value) = up(1)
Operation Status (value) = up(1)

lanadmin -g 4 excerpt:
PPA Number = 4
Station Address = 0x12799e3da4
Administration Status (value) = up(1)
Operation Status (value) = up(1)

lanscan -q
900 1 4

ioscan excerpt:
lan1 iether CLAIMED HP A7012-60001
lan4 iether CLAIMED HP A7012-60001

[Tim Nelson]

Lots of info like this
"Also, all packets for a specific data flow always flow out through the same physical port until
the data flow is aged out of the distribution table. This means that in order to generate
simultaneous load on each of the physical ports in a link aggregate, start multiple data flows
over the link aggregate."

can be found here
http://www.docs.hp.com/en/netcom.html#Auto%20Port%20Aggregation%20%28APA%29

[rick jones · Accepted solution]

LB_MAC works best when the system is speaking with many remote MAC (Ethernet) addresses. If the bulk of the traffic is going to only two MAC addresses, then if you aren't lucky with those two MACs you will only get one link used.

Similarly, if you load balance based on IP, if there are only two IPs with which you are speaking, unless you happen to have picked the IPs "right" you will still have an issue with getting things across both ports.

If you tell it to use TCP (or UDP) port numbers (LB_somethingIcannotrecall) then if you have a "large enough" number of TCP connections, then you should get decent spread, even if you were speaking to only one or two IP or MAC addresses.

Of course that only addresses the outbound traffic. The inbound traffic will depend entirely on what you've setup on the switch.