Hi Pavel -

I believe that what you are describing is exactly what I'm looking for, but I 
did not realize this was the proper way to configure.  Can you please provide a 
configuration example?

Thanks again for all of the input.


________________________________
From: Павел Лунин [[email protected]]
Sent: Monday, January 16, 2012 3:58 PM
To: Paulhamus, Jon
Cc: Ben Dale; [email protected]
Subject: Re: [j-nsp] SRX650 cluster - ethernet switching issue


The case what not that I was connecting end points directly to the SRX, it's 
that I wanted 2 trunk links between each SRX node and the switch stack (there 
is only 1 switch stack),  each of the 2 links supporting different VLAN's.  So 
- 2 links from the primary node to the  switch stack, and 2 links from the 
secondary node to the switch stack as well...  this does not work with STP 
enabled as 3 of the 4 links get blocked by STP.   I needed a setup like this as 
I'm pushing over 1Gb through each switch link.


My favorite design is to connect each SRX to its own (no cross-links) VC-member 
using several physical links (as many as you need for performance) and to use 
L3 on top of reth VLAN units, each of which includes two physical links 
(primary and secondary). You can distribute VLANs across reths manually, just 
as you would do for STP (if it worked). At the SRX side you have several reth 
interfaces with units on them, at the VC side you use interface-range for 
bundling ports connected to primary and secondary SRX into a single config 
knob, which is really useful. Of course, on SRXes, when you move a VLAN X from, 
say, reth0 to reth1, you also need to replace reth0.X to reth1.X in the rest of 
config (zones, etc) but JUNOS allows you to do so with a single command.

You can either bound all the reths into a single RG1 (always active/passive) or 
put each reth into a dedicated RG (partial active/active). You can even easily 
make different nodes act as master for different RGs, though in most cases it 
will give nothing except pain in the rear. I love the first approach (one RG1 
for all reths) because it's much simpler. RG1/2/3/etc failover is quite fast 
(sufficient for most applications) so failing over all the reths to backup node 
in case only one of the primary node links fails is not a very high price for 
the simplicity.

A small drawback of this design is h-shape switching, if you connect downlink 
devices to the VC with LAGs. Traffic will come to the VC balanced between the 
switches connected to active and backup SRXes. So the VC will first forward the 
frames to the switch, connected to the active SRX via internal VC link. But if 
we consider a VC of 2×EX4200 connected with two VC cables, this is not much of 
a problem.

You can also add cross-links and bound four interfaces into a single LAG/reth 
(a hybrid of the two) on SRX (two links on master are active, two on backup are 
down), but JUNOS does not allow to bound two ae interfaces into an interface 
range on the EX side. So for each reth on SRX you will have two ae's on EX.This 
is hateful and prone to mistakes. On the other hand this approach will give you 
the ability to balance traffic across two links (SRX1―EX1 and SRX1―EX2) 
automatically with hashing (limited to two links only) and additional speed of 
switching over LAG members in case of a failure. When switches are connected 
not with 2×32G cables but something else (1G llinks or 10G and it's an SRX High 
End cluster) this approach will also save some resources because of avoiding 
interswitch forwarding, as described above. Though in my experience it's not 
usually worth the 'two on EX ― one on SRX' interface matching headache.

--
Regards,
Pavel

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