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prairiesky

join:2008-12-08
canada
kudos:2

redundant wireless links

How to do you guys do redundant links and monitoring of them? What protocols and such? Any specific equipment? I'm looking to increase the reliability of my system and don't know enough about it. I remember looking into it a long time ago but found the problem was that having 2 wireless links with different capacities was a hard thing to balance out. Say 2 different manufacturers.

thoughts/ideas?


Rhaas
Premium
join:2005-12-19
Bernie, MO
OSPF for the IGP. Nagios to monitor them - using a loopback interface/ip.
--
I survived Hale-Bopp!

OHSrob

join:2011-06-08
reply to prairiesky
Spanning Tree Protocol on your switch's allow you to have a redundant fail over on your network as well but on layer 2 as opposed to layer 3.

edit: I am also assuming you have a real switch such as a Cisco (not linksys or cisco home/small business), HP procurve or dell force10.

The best question to determine what technology is right for you is probably to get you to post a topology diagram.

edit: Were on cacti for monitoring.

prairiesky

join:2008-12-08
canada
kudos:2
reply to prairiesky
I had looked into STP, but that seems like pure fail over as opposed to load balancing..... I'm thinking i'd rather load balance....

I'll look into the ospf stuff.... from the 2 minute read I just did, it seems like it happens through routers? Or does it get programmed into the switch?

OHSrob

join:2011-06-08
said by prairiesky:

I had looked into STP, but that seems like pure fail over as opposed to load balancing..... I'm thinking i'd rather load balance....

I'll look into the ospf stuff.... from the 2 minute read I just did, it seems like it happens through routers? Or does it get programmed into the switch?

You need a Layer 3 switch or a router to do routing protocols such as OSPF, IS-IS, EIGRP, RIP, BGP and load balancing.

edit: What type of switch's are you using ?

prairiesky

join:2008-12-08
canada
kudos:2
smart switches currently, and they've been fine for what I have been doing, but i'd like to start getting everything backed up so I have some extra confidence and such.... They're FS726T's and have been really good, they have STP which I played with and setup previously.

I do have a 2950 kicking around as well.....


Inssomniak
The Glitch
Premium
join:2005-04-06
Cayuga, ON
kudos:2
I used the 726t for years, now I am up to the gigabit version of that switch. Never let me down. I don't use it for stp though, I use OSPF.
--
OptionsDSL Wireless Internet
»www.optionsdsl.ca

mwtn

join:2013-08-12
Casper, WY
reply to prairiesky
We use Zenoss for the monitoring and Mikrotiks to handle OSPF. Our Network is a big ring

j2sw

join:2006-05-02
Williamsport, IN
reply to prairiesky
OSPF across redundant links with some weighting. You can also combine two links into a full duplex type of setup with failover. Can be done with any OSPF router.
--
»www.mtin.net/blog
»j2sw.mtin.net/blog

prairiesky

join:2008-12-08
canada
kudos:2
any recomoendations on an easy to learn, reliable, affordable switch... gig prefered, but not needed.
Are the ubnt edgemaxs suitable? Or HPprocurves? model #s? I like my netgear and it's been reliable, but would like to be able to see throughput stats.

prairiesky

join:2008-12-08
canada
kudos:2
reply to prairiesky
just for clarity..... what i'm looking to do would be to trunk 2 wireless links together...... but when i tried that, it didn't seem to work overly well using the "trunking feature"

radio1a---------------radio1b
tower1 tower2
radio2a---------------radio2b

Then have them load balance between the 2 and fail over if one goes down. They'd be transparent ideally.

spectrumhead

join:2009-05-03
reply to prairiesky
nothing better than Juniper EX Series Switches.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to prairiesky
said by prairiesky:

just for clarity..... what i'm looking to do would be to trunk 2 wireless links together...... but when i tried that, it didn't seem to work overly well using the "trunking feature"

radio1a---------------radio1b
tower1 tower2
radio2a---------------radio2b

Then have them load balance between the 2 and fail over if one goes down. They'd be transparent ideally.

AFAIK, there are no commercial product that address this exact problem. There are some multi-WAN routers which come close but their WAN throughputs are designed for DSL/Cable.

Curiously my old company developed a solution for truly transparent trunking of mismatched parallel links many years ago. It was originally designed to parallel a FSO link with a 5Ghz PtP, but I made it generic enough for upto 4 links of any kind and any throughput.

The prototype was developed on a really expensive off-the-shelf PCI board which had a Xilinx FPGA driving 4 10/100 ethernet ports. Sadly, my company ran out of money to make a lower cost FPGA board for commercial product.

The FPGA is essential to implement the low latency scheme to merge the links transparently. I will check if there are affordable PCIe FPGA boards with quad gigabit ports and adapt my solution for today's high throughput PtP links.

OHSrob

join:2011-06-08

1 edit
reply to prairiesky
said by prairiesky:

any recomoendations on an easy to learn, reliable, affordable switch... gig prefered, but not needed.
Are the ubnt edgemaxs suitable? Or HPprocurves? model #s? I like my netgear and it's been reliable, but would like to be able to see throughput stats.

If you have any previous training with cisco IOS you can pick up a 3550 with the EMI license pretty cheep on ebay. They support pretty much every feature you could ever want or need. They also have Cisco Express Forwarding so the hardware is making the switching/routing decisions through the ASIC so CPU is used very little.

If you don't have at least CCNA 4 your probably going to have a bad time with cisco.

You could set it up as a router and set up round robin to go over 2 wireless connections if you wanted to try to keep the load as equal as possible.


TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5
reply to lutful
said by lutful:

AFAIK, there are no commercial product that address this exact problem.

Any switch that does LACP can do this.

Also known as Port Channel in Cisco land.

But, you need to make sure that your radios will pass L2 PDUs transparently else this will probably not work.

Other things to consider when using LACP are source and destination MAC and IP addresses of your traffic, and the hashing algorithms available on your chosen switches to make sure you can get some useable load balancing out of them.


TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5
reply to OHSrob
said by OHSrob:

They also have Cisco Express Forwarding so the hardware is making the switching/routing decisions through the ASIC so CPU is used very little.

But they also do not do IPv6 routing in hardware, so if you are ever planning on IPv6 being a big part of your network (and who isnt...) then a few years down the line youre going to find yourself looking for new switches again.

You'll want to hope that by then switches that can do IPv6 in hardware will be readily available on places like ebay.


TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5
reply to prairiesky
said by prairiesky:

it didn't seem to work overly well using the "trunking feature"

I suspect the trunking feature might have been referring more to VLANs than aggregating multiple links together.

prairiesky

join:2008-12-08
canada
kudos:2
i'm not 100% sure on that one, but it would make sense....

so is OSPF a viable solution for what I want to do? I'm not doing huge traffic loads, maybe 30 meg, but want the redundancy of 2 links.

I'm about to pull the trigger on some edgemax's.... is this what I want?


TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5

2 edits
If your network is bridged then forget about OSPF.

If your network is routed then OSPF is a good candidate, as long as your routers support (un)equal cost multipath routing.

This allows for two or more routes to the same destination to be installed in to the routing table, and depending on the hashing algorithm can allow for traffic to be load balanced across two or more links.

This gives you load balancing and fault protection since if any link goes down, then traffic just shifts over to the remaining one(s). When it comes back up traffic is redistributed amongst all paths again.

edit: I dont see anything in the EdgeOS manual about equal cost or multipath routing, so you might like to double check that with UBNT before you splash any cash.

prairiesky

join:2008-12-08
canada
kudos:2
thanks. So i guess STP will provide the fail over I'm looking for, but won't combine the capacities.... I can't believe i'm the first one to want this....

prairiesky

join:2008-12-08
canada
kudos:2
I found this guy who was able to bond 2 links together....

»community.ubnt.com/t5/EdgeMAX/bo···p/325183


TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5
reply to prairiesky
Read my reply to lutful.

If you have switches that can do LACP theres a chance you can have aggregation and load balancing in a bridged network.

The trick is just to make sure that the switches can load balance using a hash that considers L4 headers like TCP and UDP port numbers, and that your radios are completely transparent at L2.

The reason you need to consider L4 headers is to increase the entropy available to improve distribution across your links. TCP and UDP ports are much more random than IP and MAC addresses.

prairiesky

join:2008-12-08
canada
kudos:2
ok.. Reading the end of that forum, it seems as though there maybe some issues with aggrigation.... mainly due to them being wireless links where the switches themselves are used to ethernet, so they have no way of knowing which link is up (they base it off eth up/eth dn) and those don't change if the link drops out!

ubnt seems to be working on a solution to this problem by the sounds of it.


TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5

4 edits
Well that might just be a configuration issue. e.g. LACP "on" mode will just assume a link is ready to go as long as it is protocol up, and that basically just means what ever is plugged in to it is turned on. "Active" mode will actually try to determine that the link is valid by exchanging "control" packets.

Wireless should have nothing to do with it either. If the wireless radios are transparent at L2, then the switches on either end are none the wiser about what is in the middle. And this is kind of what transmission networks are meant to do (IMO), and why I tend to be weary of all the cheapie radios. Based on my experience at my former work place, they never seemed to be too good at "just doing nothing" with what I was trying to push through them.

If you want something that will "just work" and isnt based on open source software of sometimes questionable reliability, grab a pair of Cisco/Juniper/HP/et al switches. Go with the "pros" because at least, and theres a reason why, their stuff is proven by countless enterprise and service provider networks.

Off the top of my head:

Something like a Cisco 2955C can be powered by 24VDC, is DIN rail mountable, fanless (convection cooled), and comes in a couple of models all of which contain 12x 10/100 ports, and depending on the model fibre or copper uplink ports. For the 2955C specifically, place one of them at either end of your link and you could aggregate a couple of = 100mbit links and spit them out on one of the 10/100/1000 interfaces.

I dont believe they are very common on the likes of ebay though.

edit: But before you go out and buy any of them, I had a look at the load balancing methods available, and the 2955 can only do source or destination MAC.

The 2960 series at least support load balancing by source and destination IPs, and this would give a much nicer spread.

There is a sub-1RU 2960 chassis with something like 8 10/100 ports and 1 10/100/1000 port, or you can get a bigger model and just replace the existing switch(es) at your POP. I dont believe there is a DC option for these though.

And the good thing about LACP is that it is an open standard, so it should in theory work between any other device that supports it - no vendor lockin.

OHSrob

join:2011-06-08
reply to prairiesky
I second toms's recommendation for LACP, I used it once in the lab and it worked just fine.

edit: I also agree with the go with the pro gear there is a reason they are used extensively in enterprise and service provider networks.


TomS_
Git-r-done
Premium,MVM
join:2002-07-19
London, UK
kudos:5
reply to TomS_
Outside of Cisco, there is the Juniper 2200C. Its an AC only box IIRC, but it has 14 10/100/1000 ports on board, 12 of which are PoE capable, and the other 2 are dual personality so you can plug in some fibre at a later date if you need to.

They are sub 1RU, but you can get a rack mounting kit for them.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

1 edit
reply to TomS_
said by TomS_:

said by lutful:

AFAIK, there are no commercial product that address this exact problem.

Any switch that does LACP can do this.

Curiously, I was motivated to develop the custom FPGA solution because of my in-depth knowledge of 802.3ad from the 1990s. The following news release is from April, 1998 ... when I was working at Plaintree Systems, which was a pioneer in Ethernet switching and link aggregation.

»www.thefreelibrary.com/Interop-e···20533512

In multi-vendor tests sponsored by Sun and conducted by an independent testing organization, The Tolly Group, Plaintree's WaveSwitch(TM) 9200 interoperated smoothly with Sun's servers.

...

What is Trunking

Trunking, sometimes called link aggregation, combines multiple links into a single, logical trunk. The individual links share the traffic load. This results in increased bandwidth and increased survivability. If one or more links in the trunk are disabled, the remaining links continue to operate.


P.S. Plaintree suffered same fate as other Canadian tech pioneers ... Nortel a few years later and most recently Research in Motion.

*** Well, it seems every company is trying to improve on the IEEE standard.
»en.wikipedia.org/wiki/Link_aggregation

In addition to the IEEE link aggregation substandards, there are a number of proprietary aggregation schemes including Cisco's EtherChannel and Port Aggregation Protocol, AVAYA's Multi-Link Trunking, Split Multi-Link Trunking, Routed Split Multi-Link Trunking and Distributed Split Multi-Link Trunking, ZTE's "Smartgroup", or Huawei's "EtherTrunk".

Most high-end network devices support some kind of link aggregation, and software-based implementations – such as the *BSD lagg package, Linux' bonding driver, Solaris' dladm etc. – also exist for many operating systems.


Expand your moderator at work

dev0

join:2013-05-25
reply to prairiesky

Re: redundant wireless links

Check out performantnetworks.com ... haven't tried it yet, but it looks like a decent solution.