I'm sure I'll be shamed for asking this question, I almost want it. I'm the proud owner of 2 new Catalyst 3850 XS 10G SFP+. The Hardware install guide shows many examples of 3,5, switches in a stack. What about 2 switches. If I call the data Stacking ports "left" and "right", do I connect one stack cable between two switches, or do I connect two stack cables between two switches... e.g.; Switch-1 --- Left to Switch-2 Right --- Switch-2 --- Left to Switch-1 Right ---- Or Switch-1 Left to Switch-2 Right.... or.... see what I mean. I cannot find any definitive universal description of how best to connect them. Maybe I missed that tidbit... Chime in and feel free to pummel me... ;-D ... View more

Hello, I thought I posted this question but can find no evidence of it. So forgive me if I repeat myself. I would like to find an "examples" of setting a login user to have a limited set of functionality. I searched within IoS command refreences and discovered command "privilege exec level 10 configure". This lets a user with privilege 10 access the exec command "configure". I'm wondering how granular I can make this. I want to have a user who can go to a range of ports (or media type), and have the ability to do a "shut" - "no shut". Also setting the Vlan of a port. So far I've been marginally successful (that's actually a fail). If anyone has any insight into or a good source of configuration examples using this feature I would appreciate if you shared your insight. ... View more

I have a core infrastructure network built on the 6506E chassis. I have the CEF720 8 port 10GE with DFC blades (WS-X6708-10GE). I have purchased 4 CVR-X2-SFP10G (V03) modules, and 2 of each of the SR and LR SFPs for them. What is happening is that any of the CVR-X2 modules with the SFP-10G-LR sfp inserted is not recognized (expample next shows an OK SR sfp, followed by an LR sfp): Port         Name               Status       Vlan       Duplex  Speed Type Te1/1/7      SFP-10G-SR Mod     notconnect   5            full    10G 10Gbase-SR But none of the SFP-10G-LR modules are recognized whether in the same port or blade: Port         Name               Status       Vlan       Duplex  Speed Type Te1/2/7       SFP-10G-LR Mod     notconnect   1            full    10G unknown I cannot find any "bug" on my CCO web. A local Cisco Gold partner says that all should work together. Cisco's web site and data sheets all say it's AOK. This is not looking good. Without the LR modules, These same blades have older CVR-X2 modules with both SR, LR and Copper 10GB sfps installed and working. What could be going on here?     ... View more

I had a strange occcurance with this POE switch, the C2960CPD. First of all you must know that this switch sits at the end of about 260' of cat6 copper cable on a rooftop. It is not easy to get to. So... I needed to make some possibly questionable configuration changes to the trunk port. This port is both connectivity to the switch, and POE source. One of several configuration changes caused me to loose connectivity to this remote switch. So, I did a "shut" to the local switch that supplies POE to this switch, effectively turning off the switch. I then "no shut" that port, to power up the remote switch again. Here's the question! After bringing the port back up, I couldn't regain connectivity to the C2960C. When I climbed up onto the roof (80' up a ladder)... I found the switch was up, and the configuration I was testing was present. As if I had done a copy running-config startup-config command. I had not. Is there a command on this IOS that causes it to behave like CAT-OS, where any change is immediately written to the startup-config actively? I've looked at the "config mode ...." commands, but don't really understand them yet. In any case - I really need this to NOT work in that way. In case there is a mis-configuration - power-cycling the switch is preferable to a long climb up! ... View more

This one has puzzled me and others for some time. It's not a show stopper in that it doesn't break the network (for long). I'll have to explain some topology here to differentiate clearly from where it does occurr, and where it does not occurr. See the attachment for the topology diagram. Here's what happens. We have a VSS core and are using active VTP. The 2960 switches are all trunked to the VSS core. They are all trunked the same, with the same simple config as follows (including the Switch-1 to Switch-2 link via the M1-S1 Ubiquiti RF system). Interface Gi1/0/XX   switchport mode trunk   switchport trunk native vlan 999   switchport nonegotiate   switchport trunk allowed vlan 5,10 Note: The allowed statement above is not shown in the topology picture but is there to limit the number of times this happens to just two vlans On any "Other Cisco 2960S" switches, I never, ever see this occurr. However - across the Ubiquiti RF M1-S1 link, on Switch 2, the following occurs with regularity. It will occurr on any and every VLAN allowed across the trunk. Only on the Switch-2. Switch-2 has a single host connected to port 10 (on Vlan10). Vlan 5 is the management vlan. Those are the only two vlans allowed to cross the link. Switch 2# show logging ! 006585: Nov 15 15:25:33 PST: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet1/0/48 on VLAN0005. 006586: Nov 15 15:25:33 PST: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan5, changed state to down 006587: Nov 15 15:25:33 PST: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet1/0/48 on VLAN0005. 006588: Nov 15 15:25:33 PST: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan5, changed state to up   ! The same thing will occur for VLAN10 Show trunk (on interface used in links): Switch (1 or 2) #show int gi1/0/48 trunk Port        Mode             Encapsulation  Status        Native vlan Gi1/0/48    on               802.1q         trunking      999 Port        Vlans allowed on trunk Gi1/0/48    5,10 Port        Vlans allowed and active in management domain Gi1/0/48    5,10 Port        Vlans in spanning tree forwarding state and not pruned Gi1/0/48    5,10 I have tried every thing I can think of to stop this behavior, to no avail... I hope someone has seen a fix for this as it does cause very short network interuptions... Thanks ... View more