ElasticXL Traffic Distribution question

[marcyn]

Hi ChackMates,

There is one question that bothers me ... how does exactly work traffic distribution in ElasticXL ?
And I'm not talking about that we have General Mode in ElasticXL.

I'm talking about how does it work in ... general 😉
Let's suppose that we have 2 gateway nodes ... one is obviously SMO.
Each and every traffic first goes to SMO (as it works like pivot in classic ClusterXL Unicast Mode).
Then SMO decides that it will consume this traffic or maybe this 2nd node will do that.

This is a theory ... but how exactly does it work ?

1) LAN Client sends traffic to Internet
2) Traffic goes from Client to switch (this one where LAN segment is connected to) then to SMO ... then SMO decides that 2nd node should process this traffic
3) Traffic goes back to the same switch and then to port on that switch where 2nd node is connected

Does it work like that ?
I don't believe that in case SMO decides that 2nd node should process this traffic, then this traffic will be send via sync interface .... because it will have no sense at all and it could be a huge bottleneck.

Is it works as I described ... how exactly does it work since we only have one MAC in ElasticXL cluster ... so 2nd node does not have it's own MAC ... so how does this switch will know that traffic that will go back from SMO (let's say port1 on this switch) should go to 2nd node (let's say port2 on this switch) ?

Is there any technical documentation about this process that describes this traffic distribution a little bit more deaply ?

--
BR
m.

[emmap]

Yes.

[Bob_Zimmerman]

We are talking the same thing: a MAC address which is set fully in software, with no relation to any hardware identifier of the interface. Multiple members can only have the same unicast MAC address when only one of them can be active at a time. This is either a classical ClusterXL HA cluster, or an ElasticXL cluster with one member at each "site", since the "sites" are the HA part of ElasticXL's "HA Over LS" clustering mode.

The MAC address on most traffic-bearing interfaces of an ElasticXL cluster is virtual. The MAC address of my eth2 should end in a6. The interface named Mgmt seems to retain its real MAC address, as does the interface which ends up in the Sync bond (in my case, eth1).

ElasticXL could conceivably be updated at some point to use multicast VMACs, which would let all members receive the same traffic, then discard the part the other members will handle, like a classical ClusterXL multicast load sharing cluster.

[Alex-]

Could you make an ElasticXL with 3600 models?

It's not supported according to sk184022.

[emmap]

Where there's a will... 

There's an 'ElasticXL in the lab' thread floating around with instructions on how to hack it to work on unsupported appliances. It's a faff, and it breaks when you patch it, but it works otherwise.

[Bob_Zimmerman]

ElasticXL on 3600/3800 units (and open servers and VMs) is explicitly supported in the R82.20 public EA with the release notes directing you to sk183513.

[Mike_Jensen]

Does this introduce the possibility of latency or delay for sessions being handled by the non SMO since this extra step is required?

[PhoneBoy]

Since the SMO has to receive the traffic first before forwarding to the other member, yes.