[j-nsp] Chassis cluster and forwarding performance

[Pavel Lunin]

> (This is for packet mode J-2350) I've been reading on chassis cluster,
> and noted that data plane is active/active mode,  does that mean
> double PPS in general?
As there is no flow state, there is no need for cluster in packet mode.
And it is not supported.

In general active/active data plane for JSRP cluster means you can place
reth interfaces into different redundant groups, where different nodes
are active. There is just no special 'mode' inside JUNOS for
active/passive, and it's totally up to you how to group your interfaces
and behave when one of them fails. You can attract all traffic to one
node or divide it between nodes.

Routing a packet between interfaces placed into RG's where different
nodes are master requires h-shape forwarding (through the fabric link),
that is where double pps occurs. But there is nothing pushing you to
route like this.

In my opinion, nearly 100% of real-word FW cluster implementations need
a single RG1, to which all interfaces belong. This basically means
active/passive data plane behavior.

An only feasible exception might a kind of multi-tenant scenario where
traffic to/from some VLAN's is always passed through a given node. When
a failure occurs performance degrades. So you can reach more performance
under normal conditions. But I'd say it's not worth it because a 2x
hardware overkill is often much cheaper than advanced NOC skills
required  to maintain and troubleshoot the more complex solution.