Solved

Spanning-tree port fast

Posted on 2016-08-12
7
74 Views
Last Modified: 2016-08-16
Is it a good idea to have this enabled on the interface between a L3 switch and router?
0
Comment
Question by:PeraHoman
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
7 Comments
 
LVL 14

Assisted Solution

by:SIM50
SIM50 earned 125 total points
ID: 41753949
Yes if a router is not configured for bridging. Just to be safe, put the following command:
spanning-tree portfast bpduguard enable
0
 
LVL 28

Accepted Solution

by:
Jan Springer earned 250 total points
ID: 41753968
If it's a layer 3 interface, it should not have spanning tree configured anyway -- at all.
1
 

Author Comment

by:PeraHoman
ID: 41754037
True, I'm looking through old configs and saw it and wanted some opinions.
0
Connect further...control easier

With the ATEN CE624, you can now enjoy a high-quality visual experience powered by HDBaseT technology and the convenience of a single Cat6 cable to transmit uncompressed video with zero latency and multi-streaming for dual-view applications where remote access is required.

 
LVL 14

Assisted Solution

by:SIM50
SIM50 earned 125 total points
ID: 41754327
If it's a layer 3 interface, it should not have spanning tree configured anyway -- at all.

STP is automatically disabled once you change port from L2 to L3 on a switch.
0
 
LVL 16

Assisted Solution

by:Michael Ortega
Michael Ortega earned 125 total points
ID: 41756221
You should never have STP portfast enabled on ports between switches or routers, whether they are operating as an L3 device (switches) or not. Portfast is intended for network endpoints, e.g. computers, servers, printers, etc.

MO
1
 
LVL 14

Assisted Solution

by:SIM50
SIM50 earned 125 total points
ID: 41756329
You should never have STP portfast enabled on ports between switches or routers, whether they are operating as an L3 device (switches) or not. Portfast is intended for network endpoints, e.g. computers, servers, printers, etc.

I don't completely agree with this statement, specifically the bolded part.
According to Cisco best practices:

Configure STP PortFast only on ports that are connected to end host devices that terminate VLANs and from which the port should never receive STP BPDUs, such as:
–Workstations
–Servers
–Ports on routers that are not configured to support bridging

Link: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/best/practices/recommendations.html#wp1061957

Also, when you change a port on a switch from L2 to L3, portfast is enabled automatically and the only option you have is to disable it. You are welcome to test all of this btw.
0
 
LVL 16

Assisted Solution

by:Michael Ortega
Michael Ortega earned 125 total points
ID: 41756653
@SIM50

I misspoke. Bridging is the key. I guess I didn't quite think of it in the way of a true router where you're essentially L3 on each interface. I was thinking more in the application where you're connecting your environment to a firewall, where in many cases SMB sized firewalls have all the inside interfaces bound together as a bridge/switch.

Good point, and thanks for clearing that up. Where you employ bridge/switch to bridge/switch communication you want portfast off.

MO
0

Featured Post

Easy, flexible multimedia distribution & control

Coming soon!  Ideal for large-scale A/V applications, ATEN's VM3200 Modular Matrix Switch is an all-in-one solution that simplifies video wall integration. Easily customize display layouts to see what you want, how you want it in 4k.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
ASA 5506 blocks telnet 11 35
ASA 5505 packet drops 14 57
Cisco 887VA secondary outgoing IP Address diferent from Default Dialer 4 53
Cisco SPA525G2 - Stuck on Cisco Screen 3 18
Exchange server is not supported in any cloud-hosted platform (other than Azure with Azure Premium Storage).
Concerto Cloud Services, a provider of fully managed private, public and hybrid cloud solutions, announced today it was named to the 20 Coolest Cloud Infrastructure Vendors Of The 2017 Cloud  (http://www.concertocloud.com/about/in-the-news/2017/02/0…
Viewers will learn how to properly install and use Secure Shell (SSH) to work on projects or homework remotely. Download Secure Shell: Follow basic installation instructions: Open Secure Shell and use "Quick Connect" to enter credentials includi…
Both in life and business – not all partnerships are created equal. As the demand for cloud services increases, so do the number of self-proclaimed cloud partners. Asking the right questions up front in the partnership, will enable both parties …

749 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question