[j-nsp] General MX notes for use as a core ethernet switch...

[Derick Winkworth]

Fiddling with the MX for a POC-like session, I found a couple of things 
others may find interesting...

1) On etherchannel bundles, traffic is distributed per destination-mac, 
per source-mac, or both.  Unfortunately, this is not configurable on a 
per-link basis, only globally.  So, for us, this means we will be using 
both...

"forwarding-options hash-key family multiservice ..."

2) On an IRB interfaces, there is the annoying requirement of specifying 
a layer-2 interface in a static arp definition.  This annoying 
requirement remains true even in the case of a multicast-mac.  For some 
reason, configuring static ARP means the MX can't learn that MAC 
address... which is highly inconvenient when you need to use a multicast 
MAC address (like active/active multicast mac firewall configurations).

3) To be 100% compatible with Cisco's PVST+, you need to use 
"force-version" and make sure you are configured for STP and not 
rapid-pvst...

4) VRRP uses a virtual MAC, so there is no dependency on gratuitous ARPs 
or ARP timeout parameters on hosts.  Not a big surprise or anything, but 
it was nice to see it work as expected...

5) These are MDI-crossover ports.  If you are doing a core-switch swap 
with existing "switches" you will need to put cross-over cables in!!!