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RHEL Bonding mode0

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brian_31
Super Advisor

RHEL Bonding mode0

In RHEL is not mode0 active-active? . What is the difference between mode 0 and mode 4 and which is better? How would you set this up?

Thanks

Brian
4 REPLIES
Matti_Kurkela
Honored Contributor

Re: RHEL Bonding mode0

http://www.mjmwired.net/kernel/Documentation/networking/bonding.txt#436

Mode 0 is round-robin: a simple transmit load balancing. Whether received traffic is load-balanced or not, depends on the system sending the data (or the local side of the gateway, if the sender is not in the local network segment) and the switch/hub used.

Mode 4 is IEEE 802.3ad standard-compliant link aggregation. It works only if the switch to which the bonded NICs are connected is configured to support link aggregation. If the switch is not configured, or if the NICs are connected to two different switches which aren't configured to share IEEE 802.3ad information, this bonding mode will definitely fail.

If the server with the bonded NICs is connected to network switch(es) with MAC address hijacking protection enabled, most bonding modes may fail. In Cisco terminology, this is "port-security".

There is no single "optimal" set-up: knowledge of your network switch features and configuration is required to choose a good set-up for your situation.

MK
MK
JL Martinez
Advisor

Re: RHEL Bonding mode0

I've seen mode 0 bringing a whole network to its knees. I recommend using switches with 802.3ad support.
brian_31
Super Advisor

Re: RHEL Bonding mode0

So, how do i set up an active-active using bonding? I have a test server which has one ip? could i test using that? I did not see active-active set up in the tha doc above? Anyone know how?

Thanks

Brian.
Matti_Kurkela
Honored Contributor
Solution

Re: RHEL Bonding mode0

Mode 1 is active/passive; all others are different types of active/active.

The number of IP addresses is not important when testing bonding; the important thing is that you have 2 or more physical NICs.

You should talk with your network administrator.
Questions to ask:
- To which switch(es) is the test server connected?
- Can it/they support IEEE 802.3ad link aggregation?
* if the answer is yes, then:
- Could you please configure the switch to accept 802.3ad in ports?
* if the answer is something like "yes... wait a moment... now it's done", then (and *only* then) you can use bonding mode 4!

If 802.3ad is not supported or the network administrator cannot configure it, then one more question:
- What happens if the switch sees one MAC address first in one port, then in another port, then back in the first port, and so on? Will it accept the traffic? Will the switch get overloaded? Or will the switch disable both ports and log a "port security violation"?

If the two (or more) NICs of the test server are to be connected to two separate switches, then:
- What happens when the upstream switch/router/firewall sees one MAC address first in one port, then in another port, then back in the first port in a rapid sequence? Will it accept the traffic immediately, will it stop the traffic to that MAC address until its ARP table or MAC address cache entry expires, or will it stop the traffic and log a security violation?

If the answer to one of the 2 previous questions is "security violation", the last question is:
- Would it be possible to disable this security protection for these particular ports or MAC address(es)?

When you have the answers to these questions, you will have enough information to determine if you can use any active-active bonding mode at all.

MK
MK