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LeftHand bonding: how to prevent L2 isolation

aeronet
Frequent Advisor

LeftHand bonding: how to prevent L2 isolation

Hi,

is there a way to configure arp_validation of the bonding module in LeftHand? W/o a mechanism like arp_validation single nodes might become isolated from the network (e.g. ISLs of the attached switch of the active link are down).

TIA
3 REPLIES
Ivanbre
Frequent Advisor

Re: LeftHand bonding: how to prevent L2 isolation

There are 3 types of bonds on lefthand.

1.Active â Passive
2.Link Aggregation (802.3 ad)
3.Adaptive Load Balancing

I'm assuming you mean ALB.

Now when you are using ALB the bond NIC modifies its answers to arp queries and arp responses on the fly making traffic with one L3 address appear to have multiple L2 addresses depending on which host you ask.

Now i don't think Adaptive Load Balancing works at L2 layer but at L3 layer as it's manipulating l2 addressess.(something like that ) So if you want to use ARP validation i think you will break your whole ALB setup. I really don't know if it's possible but it's useless when you use ALB and i guess unsupported.
aeronet
Frequent Advisor

Re: LeftHand bonding: how to prevent L2 isolation

It's clear how ALB and the other issues are working. With a L2 failover setup like bonding there is the danger of isolating network traffic.

Imaging the following: there is a host we two NICs. Those NICs are configured as a bonding interface (the mode does not matter). Each of the interface is connected to a different switch. Those switches are linked to the rest of the network. If one of the switch becomes isolated (due an broken ISL) the bonded interface won't have a chance to recognize this issue and disable the isolated link if there is now arp_validation enabled.

Ivanbre
Frequent Advisor

Re: LeftHand bonding: how to prevent L2 isolation

So why would you connect your iscsi network to rest of your network?