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Fallback bedween a Laserlink and a HDSL modem line

hi ng,

please have a quick look at my drawing it describs it all, so all of us talk about the same thing.

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As you can see we got two buildings witch are connected via Laserlink and via HDSL backup line. The Laser works at 100MBit pretty good, --> only with nice weather ;-) The HDSL line gets around 4 MBit through.

We want to build a system or config witch alowes us to automaticly switch bedween the lines. we tried spanning tree but got loops with fogy weather. so now we still do it manualy pluggin in and out one link at a time at one side of the buildings. (Laser or Modem up)

i asume a big problem we have to manage are thes marked medium converters from RJ-45 to fiberoptic glas lines. our cisco's see the converters interface always as up, even while the lasers lost connection because of the fog! so we have to create a system/config witch checks the troughput of the lines not the uplink status. somebody told me about how i could get my vlans or dot1q trunkport over ospf. my cisco skill levels are not that high as i would like them ;-) and i never worked with ospf so if you know what he might ment, it would be nice to get some hints. other suggestions then ospf? thank you

Greetings Colin

Reply to
C Cant
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hi ng,

please have a quick look at my drawing it describs it all, so all of us talk about the same thing.

formatting link
As you can see we got two buildings witch are connected via Laserlink and via HDSL backup line. The Laser works at 100MBit pretty good, --> only with nice weather ;-) The HDSL line gets around 4 MBit through.

We want to build a system or config witch alowes us to automaticly switch bedween the lines. we tried spanning tree but got loops with fogy weather. so now we still do it manualy pluggin in and out one link at a time at one side of the buildings. (Laser or Modem up)

i asume a big problem we have to manage are thes marked medium converters from RJ-45 to fiberoptic glas lines. our cisco's see the converters interface always as up, even while the lasers lost connection because of the fog! so we have to create a system/config witch checks the troughput of the lines not the uplink status. somebody told me about how i could get my vlans or dot1q trunkport over ospf. my cisco skill levels are not that high as i would like them ;-) and i never worked with ospf so if you know what he might ment, it would be nice to get some hints. other suggestions then ospf? thank you

Greetings Colin

Reply to
C Cant

Try looking at

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there are some really good examples how to do what you want...

Reply to
Ivan Ostres

It is indeed easy to use a dynamic routing protocol such as OSPF to switch routes in the event of link failures however the usual focus is that the links fail completely and then the alternative path comes to life.

I can imagine though that a laser link will not always behave in this way and might be liable to link degradation.

In Cisco kit OSPF for example by default does not stop using a link until it loses (sorry I forget the exact details) about 4 "hello" packets each seperated by a 10 second interval.

This means that if one of the three hellos gets through then the link will not be defined to be down. This may not be the result that you want.

I do not know the full solution to this however it is possible to "tune" the hello timer and the number of hellos to miss before the link is declared down.

PPP has a link quality monitoring facility but I do not know if it is possible to run PPP over what I would gues would be an Ethernet link.

An other option might be Policy based routing

formatting link
Note first that this is pretty new, so check that it works in your environment.

I expect that yuo can get a good solution however it may rquire some thought.

Reply to
anybody43

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