I have one problem for the EX 2300 24T series switch. Today i bought Card Access Controller on my company. But when i connection to on my juniper EX 2300 24 T series switch. Card Access Controller never be port UP. However when i put one hub between switch and card. Connection is UP. How can i fixed this problem. Card Access Controller runnig vlan 1 and my Juniper switch have a default configuration. Card model is a gallagher cardax 3000.
I was thinking what @smiker stated was probably the situation. You could confirm this when the hub is in place. Just check the port speed and duplex on the hub for the links that are up. I am going to assume 1GE/1000M on interface to EX2300 and 10 (maybe HDX?) on the interface to Cardax 3000. What ever the Cardax side shows, hard code that on EX2300 and see what happens.
I know you are saying it's a default configuration.. but did you by any chance configure both rstp and vstp on you switchports?
I've seen another case with an embedded device where the link never came up but worked on a random unmanaged switch - and having both rstp and vstp on the same interface on the EX2300 or EX3400 made it break.