In your CCNA studies, you learned about PortFast and the trouble it can cause if configured on the wrong port! Suitable only for switch ports connected directly to a single host, PortFast allows a port running STP to go directly from blocking to forwarding mode.
A Cisco router will give you a warning when you configure PortFast:
Voice Service Bridge
SW1(config)#int fast 0/5
SW1(config-if)#spanning-tree portfast
%Warning: portfast should only be enabled on ports connected to a
single host. Connecting hubs, concentrators, switches, bridges, etc...
to this interface when portfast is enabled, can cause temporary
bridging loops. Use with CAUTION
%Portfast has been configured on FastEthernet0/5 but will only
have effect when the interface is in a non-trunking mode.
SW1(config-if)#
Not only will the switch warn you about the proper usage of PortFast, but you must put the port into access mode before PortFast will take effect.
Now, you'd think that would be enough of a warning, right? But there is a chance - just a chance - that someone is going to manage to connect a switch to a port running Portfast. That could lead to two major problems, the first being the formation of a switching loop. Remember, the reason we have listening and learning modes is to help prevent switching loops. The next problem is that there could be a new root bridge elected - and it could be a switch that isn't even in your network!
BPDU Guard protects against this disastrous possibility. If any BPDU comes in on a port that's running BPDU Guard, the port will be shut down and placed into error disabled state, shown on the switch as err-disabled. A port placed in err-disabled state must be reopened manually.
BPDU Guard is off on all ports by default, and is enabled as shown here:
SW1(config)#int fast 0/5
SW1(config-if)#spanning-tree bpduguard enable
It's a good idea to enable BPDU Guard on any port you're running PortFast on. There's no cost in overhead, and it does prevent the possibility of a switch sending BPDUs into a port configured with PortFast - not to mention the possibility of a switch not under your control becoming a root switch to your network!
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OBi110 Voice Service Bridge and VoIP Telephone Adapter Feature
- Works with Google Voice for FREE calls to the USA and Canada to 2012 - Great international rates too!
- VoIP ATA and Gateway Supports Analog Line, GV and SIP Services; Callcentric, Sipgate, Vitelity, Voip.ms, etc.
- Make free calls on the OBiTALK Network - Connect to other OBi Devices or use the free OBiON for iPhone application or OBiAPP for your PC.
- Some of the OBi110 Calling Features: Call Forward, Caller ID - Name - Number, Anonymous Caller Blocking, Message Waiting Indication - Visual and Tone Based
- OBiTALK Portal Features: Manage Your OBi, Connect to Your Friends' OBi Devices, Add Services, Download Apps for PC, Speed Dial Up to 99 OBi Endpoints or Phone Numbers
OBi110 Voice Service Bridge and VoIP Telephone Adapter Overview
Support (technical or warranty) will be provided by the seller from whom you obtain the product. With the OBi110, you are in control of your communications life. From the OBi110's on-board connections to a telephone, your phone line and via the Internet, you have the power to bridge mobile, fixed line and Internet phone services (VoIP). The OBi provides you with an abundance of control and enhanced convenience. OBi can use the web and social networking tools to bring everything and everybody together to speak freely and even for free! When it makes sense, the OBi110 can use the Internet and OBiTALK between OBi users. In this case, a traditional phone service is never needed to make the connections. Talking becomes truly free. You can put the “social” back into social networking. So Many Features! - OBiTALK Web Portal: The OBiTALK Web Portal allows you to manage your OBi endpoints and your Circle of Trust. There is also a utility which helps OBi users configure devices for optimum savings and access applications which make using OBi even more convenient. - OBi Circles of Trust: The OBiTALK Web Portal is where you can set-up Circles of Trust. This provide a means to team-up with other people who have OBi devices and endpoints so that everyone’s calls can be made as inexpensively as possible. - OBiAPP for PC: Soft Phone Integration - Works with Your Existing Services: PSTN, VoIP (SIP). Call Forwarding on All Calls, Busy Calls, Forward on No Answer. Caller ID – Name & Number. Call Waiting. Call Transfer. Block by Caller ID. Automatic Call Back. Call Return. Do Not Disturb. Conference Calling. Anonymous Calling. Message Waiting Indication - Visual and Tone Based. Speed Dialing of 99 OBi Endpoints or Phone Numbers.Available In Stock. |
