Hello, I'm being asked to look into using BFD over our P2P transport links. Is anyone else doing this? Our transport links are all 10G Ethernet (LAN-PHY). There's no alarming inside of LAN-PHY like there is in SONET. The transport side should propagate a fiber break by stopping to send light on both ends. This is enough to cause the router interfaces to drop and for protocols to converge. Since LAN-PHY doesn't have any built end-end alarming, some folks believe that we may encounter situations where a fiber break doesn't cause interfaces do go down. Convergence would then have to wait for IGP hellos to detect the problem. Is anybody else running BFD over 10G LAN-PHY transport links? Any comments around BFD for this application in general? Thanks, Serge __________________________________________________________________ Looking for the perfect gift? Give the gift of Flickr! http://www.flickr.com/gift/
On Fri, Feb 5, 2010 at 9:45 AM, Serge Vautour <sergevautour@yahoo.ca> wrote:
Hello,
I'm being asked to look into using BFD over our P2P transport links. Is anyone else doing this? Our transport links are all 10G Ethernet (LAN-PHY). There's no alarming inside of LAN-PHY like there is in SONET. The transport side should propagate a fiber break by stopping to send light on both ends. This is enough to cause the router interfaces to drop and for protocols to converge.
We only use BFD on L2 circuits. Ethernet auto-neg includes limited link-fault signalling. It's not as good as SONET, but it will detect link-failure/one-way link.
Since LAN-PHY doesn't have any built end-end alarming, some folks believe that we may encounter situations where a fiber break doesn't cause interfaces do go down. Convergence would then have to wait for IGP hellos to detect the problem.
Have not found GigE 10GigE to be a problem over fiber. Have found BFD to be problematic depending on the implementation and CPU load of your equipment. The closer you can stay to the physical layer, the better off you are.
Is anybody else running BFD over 10G LAN-PHY transport links? Any comments around BFD for this application in general?
Thanks, Serge
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-- Tim:> Sent from Brooklyn, NY, United States
I'm being asked to look into using BFD over our P2P transport links. Is anyone else doing this? Our transport links are all 10G Ethernet (LAN-PHY). There's no alarming inside of LAN-PHY like there is in SONET. The transport side should propagate a fiber break by stopping to send light on both ends. This is enough to cause the router interfaces to drop and for protocols to converge.
"The transport side *should* propagate ..." - but are you sure this will happen in all circumstances? Unless you are certain about this, you may want BFD.
Since LAN-PHY doesn't have any built end-end alarming, some folks believe that we may encounter situations where a fiber break doesn't cause interfaces do go down. Convergence would then have to wait for IGP hellos to detect the problem.
Is anybody else running BFD over 10G LAN-PHY transport links? Any comments around BFD for this application in general?
We run it on most 10G backbone (LAN-PHY) links. In addition to the issue of link down propagation, you may also want to standardize on BFD for all your backbone links, for simplicity's sake (same mechanism everywhere). Obviously, in order to do this you want to be sure that the BFD implementation won't give you lots of false positives. Steinar Haug, Nethelp consulting, sthaug@nethelp.no
On Fri, Feb 5, 2010 at 11:23 AM, <sthaug@nethelp.no> wrote:
We run it on most 10G backbone (LAN-PHY) links.
Hmm. Backbone L2 transport, or fiber/wave type transport? I'd be surprised to hear of people running it on dark-fiber-ish stuff.
In addition to the issue of link down propagation, you may also want to standardize on BFD for all your backbone links, for simplicity's sake (same mechanism everywhere). Obviously, in order to do this you want to be sure that the BFD implementation won't give you lots of false positives.
And therein lies the challenge. Try asking Mr Steenburger what BFD stands for...
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
-- Tim:> Sent from Brooklyn, NY, United States
We run it on most 10G backbone (LAN-PHY) links.
Hmm. Backbone L2 transport, or fiber/wave type transport? I'd be surprised to hear of people running it on dark-fiber-ish stuff.
Both. For L2 transport through switches the usefulness is rather obvious. For WDM type transport because we're not 100% certain that we'll always get a link down propagated. For fiber - only for consistency, and the actual link down would normally be detected faster than BFD can react. Steinar Haug, Nethelp consulting, sthaug@nethelp.no
* Serge Vautour
I'm being asked to look into using BFD over our P2P transport links. Is anyone else doing this? Our transport links are all 10G Ethernet (LAN-PHY). There's no alarming inside of LAN-PHY like there is in SONET. The transport side should propagate a fiber break by stopping to send light on both ends. This is enough to cause the router interfaces to drop and for protocols to converge.
If only one strand in your fibre breaks, only the side that has the broken strand connected to Rx will see the physical interface go down. I've seen this happen with Extreme equipment at least. Best regards, -- Tore Anderson Redpill Linpro AS - http://www.redpill-linpro.com/ Tel: +47 21 54 41 27
On Fri, Feb 05, 2010 at 06:50:39PM +0100, Tore Anderson wrote:
* Serge Vautour
I'm being asked to look into using BFD over our P2P transport links. Is anyone else doing this? Our transport links are all 10G Ethernet (LAN-PHY). There's no alarming inside of LAN-PHY like there is in SONET. The transport side should propagate a fiber break by stopping to send light on both ends. This is enough to cause the router interfaces to drop and for protocols to converge.
If only one strand in your fibre breaks, only the side that has the broken strand connected to Rx will see the physical interface go down. I've seen this happen with Extreme equipment at least.
Not if you leave Auto-Negotiation enabled, which provides Remote Fault Indication.
We use it on all of our links which are generally over our own DWDM/dark fiber network. All links are 10G LAN PHY. Our DWDM systems propagate link failures but one of the main reasons we implemented it was our router vendors did not drop link during reboots during software upgrades. GR wasn't supported in those cases. We have had some issues with false positives but overall it has been running fairly stable for over a year. I've found the same issue with another router vendor where after an upgrade you may have to reload a line module, and the module does not drop link during a reload... Phil On Feb 5, 2010, at 9:45 AM, Serge Vautour wrote:
Hello,
I'm being asked to look into using BFD over our P2P transport links. Is anyone else doing this? Our transport links are all 10G Ethernet (LAN-PHY). There's no alarming inside of LAN-PHY like there is in SONET. The transport side should propagate a fiber break by stopping to send light on both ends. This is enough to cause the router interfaces to drop and for protocols to converge.
Since LAN-PHY doesn't have any built end-end alarming, some folks believe that we may encounter situations where a fiber break doesn't cause interfaces do go down. Convergence would then have to wait for IGP hellos to detect the problem.
Is anybody else running BFD over 10G LAN-PHY transport links? Any comments around BFD for this application in general?
Thanks, Serge
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participants (6)
-
Chuck Anderson -
Phil Bedard -
Serge Vautour -
sthaug＠nethelp.no -
Tim Durack -
Tore Anderson