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wirelessdog
join:2008-07-15
Queen Anne, MD

wirelessdog

Member

Auto Failover

So... Consider:

Edge Router -> Tower1 via Fiber -> Tower2 via Rocket 5 x Rocket 5 -> Tower3 -> Tower 4 via Rocket 5 x Rocket 5

New Link:
Edge Router -> Tower6 via Fiber -> Tower 4 via Nanobeam 5 x Nanobeam 5

Bridged network. Tower 3 is equipped with a Cisco 2950 switch. Tower 6 is connected via a Mikrotik Switch 260G I think.

Tower 4 is equipped with a Mikrotik RB2011UiAS-IN functioning as a switch.

Tower 4 will be one wireless hop away from fiber on the new link. However, I also want to keep the old link which is several hops from the edge router for redundancy.

With a bridged network and the RB2011UiAS-IN what is my best approach? RSTP or STP? OSPF? I have never used OSPF so I am completely unfamiliar with how it might work. I've looking for the simplest way to make it happen. The network is stupid so in theory if I connect both the Nanobeam and Rocket links to the same switch it will create a loop. Seems like STP would be an easy way for auto failover but can I specify the primary link if I do that? I'm also open to load balancing if there is a way to do that on a bridge.

Rhaas
Premium Member
join:2005-12-19
Bernie, MO

Rhaas

Premium Member

OSPF would be best going forward, but you'd have to route your network.

Inssomniak
The Glitch
Premium Member
join:2005-04-06
Cayuga, ON

2 edits

Inssomniak

Premium Member

said by Rhaas:

OSPF would be best going forward, but you'd have to route your network.

+1

Editing:

OSPF is just that. Open shortest path first. Path distance/cost being a definable value. If the shortest path disappears, it picks the next shortest path..

But it does require a routed network. It's easy to configure in Mikrotik..

I set up all my sites now with a router in the center that does all the MPLS and OSPF. Hang all the radios and switches off that router.

tubbynet
reminds me of the danse russe
MVM
join:2008-01-16
Gilbert, AZ

tubbynet to wirelessdog

MVM

to wirelessdog
said by wirelessdog:

The network is stupid so in theory if I connect both the Nanobeam and Rocket links to the same switch it will create a loop.

does bog standard ubnt or tik kit not support stp on l2 links by default??!
insane.

rstp (whatever flavour of stp runs that is based on the 802.1w standard on your kit) will work here as well.
generally -- rstp is 'hello' based (rather than timer based) and can greatly speed up convergence times over the 802.1d-based implementations.

to run *any* layer-2 network without the presence of some sort of loop prevention mechanism is just insane.

that being said -- if you can move to a routed core -- you can do "nifty things" (tm) -- like run bfd to drop convergence times and then run an mpls core that you can run vpn-based services at either layer-2 or layer-3.

q.
tubbynet

tubbynet to wirelessdog

MVM

to wirelessdog
replying inline since i'm lazy and want to quote your post rather than having to copy it across in the other edit window.
i realize my initial post wasn't exactly helpful.

at any rate:
said by wirelessdog:

Seems like STP would be an easy way for auto failover but can I specify the primary link if I do that?

stp is all about cost to the root bridge. you need to make sure you set the root of your layer-2 network appropriately through vlan priority or whatever. make sure that your stp instance(s) are mapped such that the "center" of your network -- whatever you determine that to be -- is static -- rather than through the general stp election process.
once you have your root bridge mapped -- everything else becomes a matter of "lowest cost to the root". in this way -- you can make sure that the "lowest cost" path is selected as the root port (i.e. the port that is facing the root bridge). you can let stp automagically calculate costs -- or you can set the cost manually.
said by wirelessdog:

I'm also open to load balancing if there is a way to do that on a bridge.

layer-2 is a single path active. you can get fancy with setting different costs per path if your stp variant supports multiple spanning-tree instances within a single domain -- but if you only have a single instance for all vlans -- then you're effed. there are technologies that are out there that allow for "trickery" -- but in a wan network -- you don't want to employ them (if they are even available on your hardware). to get true "equal cost multipathing" (ecmp) -- you'll need to move to a layer-3 network. as a side note -- the only routing protocol that supports "unequal cost multipathing" is cisco's eigrp protocol -- wherein you set variance across your different paths and the traffic weight is based on the variance ratios. rarely do you see this being done -- as well -- its more work than its worth. often if something like this is truly needed -- some sort of 'policy based routing' (cisco) or 'filter based forwarding' (juniper) is employed. cisco has their own take on this called "performance routing" (pfr) that you can use given criteria, etc into determining best path -- but given that you're not running cisco kit everywhere -- you can't employ such a solution.

q.
j2sw
join:2006-05-02
Williamsport, IN

j2sw to wirelessdog

Member

to wirelessdog
OSPF routing is the way to go. To me it is much more consistent than STP in a ISP setup. Sure it will work, but in my experience it is not as consistent. The nice thing about converting to OSPF is you can do it in stages. You can have the bridged network running alongside the routed network and switch customers over as things allow.