[AusNOG] VPLS OSPF question
Johann Lo
Johann.Lo at aptel.com.au
Wed Apr 17 10:08:42 EST 2013
True. I guess I misunderstood your question.
But I’d just K.I.S.S. and split the VPLS into VLANs (one for each state etc.) and then run each as an OSPF area. I’d assume with a VPLS cloud that size you’d have Q-in-Q.
The real impetus with deploying BGP would be if you want to run MPLS and VRFs internally but even then you could get away with VLANs and VRF-lite and leak routes via real devices e.g. inter VRF aggregation firewalls.
There’s also operational overhead, good luck getting any decent troubleshooting out of the lower levels before it escalates to senior. Ditto with implementations.
I’ve had a very bad experience with an extremely complex, BGP as internal topology network with 27 VRFs and multiple points of redistribution, any routing change turned into a CCIE lab.
From: Tom Storey [mailto:tom at snnap.net]
Sent: Wednesday, 17 April 2013 9:51 AM
To: Johann Lo
Cc: Mitchell Warden; ausnog at lists.ausnog.net
Subject: Re: [AusNOG] VPLS OSPF question
Im aware iBGP generally requires an IGP as well, to distribute loopback information at a minimum, and that is is generally slower to propagate updates than the likes of an IGP - thats all 101 stuff.
What I dont get is why this would make BGP any less useful internally. I mean, if I had to peer 200 sites across a VPLS I'd probably do it with some form of BGP rather than an IGP.
On 17 April 2013 00:05, Johann Lo <Johann.Lo at aptel.com.au<mailto:Johann.Lo at aptel.com.au>> wrote:
No, not really…. Why do you think most people run their iBGP on top of something else?
Also BGP convergence time is inferior to OSPF/EIGRP/ISIS
From: ausnog-bounces at lists.ausnog.net<mailto:ausnog-bounces at lists.ausnog.net> [mailto:ausnog-bounces at lists.ausnog.net<mailto:ausnog-bounces at lists.ausnog.net>] On Behalf Of Tom Storey
Sent: Wednesday, 17 April 2013 4:40 AM
To: Mitchell Warden
Cc: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>
Subject: Re: [AusNOG] VPLS OSPF question
Whats wrong with using BGP internally. Isnt that what iBGP is for?
On 16 April 2013 10:34, Mitchell Warden <wardenm at wardenm.net<mailto:wardenm at wardenm.net>> wrote:
Hi Brad,
Some ideas below. There are a lot of considerations...
OSPF
- Will run fine on a VPLS service. I've done this with up to 30 or so sites in the past and it works well.
- 200 is a lot of sites - I would try to break it down to multiple smaller domains.
- 50 routers in an area isn't a big deal. It will depend on the CPU and the number of updates, but even 200 is unlikely to be a problem.
- 200 neighbour adjacencies however might be a big deal (they're all on the same broadcast domain). I think 200 is too many.
BGP
- All of the routers could be in the same subnet so they would be able to reach each other directly without an IGP, if you build neighbors with interface addresses instead of loopbacks.
- You would need to use route reflectors to avoid having to mesh all 200 routers.
- I can't think of any reason BGP would reduce available bandwidth.
- BGP isn't really designed to be used internally, and I would try to avoid using it that way.
- BGP is probably better than OSPF if you can't reduce the size of the domain. It will be more scalable and probably more reliable.
Cheers.
Mitchell
Johann Lo
Senior IP Network Engineer
[cid:image001.jpg at 01CE3B53.19A4D400]<http://www.aptel.com.au/>
Asian Pacific Telecommunications
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----- Original Message -----
From: Brad McGinn
[mailto:the_xorach at yahoo.com<mailto:the_xorach at yahoo.com>]
To: ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>
[mailto:ausnog at lists.ausnog.net<mailto:ausnog at lists.ausnog.net>]
Sent: Tue, 16 Apr 2013 17:14:02
+1000
Subject: [AusNOG] VPLS OSPF question
> Hi AusNog list,
Long time listener, first or second time caller.
I
> know this list is pretty specific to Service Providers so I'm hoping any of
> you who not only know carrier networks, but also have an insight into
> enterprise networks maybe able to help me to get a view (or even help
> understanding) of the pros and cons of running OSPF or BGP across a VPLS
> network.
I respectfully ask your advice.
I am an enterprise
> network engineer, not a service provider however I hope you don't hold that
> against me. We run OSPF in our Data Centre and BGP into a MPLS network
> that all of our sites connect into.
My fairly basic understanding of VPLS
> is kind of like EoMPLS or even one big broadcast domain. I assume any
> IGP could potentially work across it but some factors must be taken into
> consideration: eg flapping sites, latency, reference bandwidth, DR/BDR
> placement, multicast transmission and so on.
So, with that in mind, I'm
> wondering the following:
- would it be wise to run an IGP across a
> VPLS backbone with over 200 sites? or would BGP be better? or even something
> else?
- if an IGP is the go, would one use OSPF?
- if OSPF, do
> you think it would be wiser to run a separate OSPF process for the VPLS
> connected sites and a separate OSPF process for the DC? and then
> redistribute or just summarise right there? (so as to protect the DC from
> OSPF recalculations when sites go up and down)
- if BGP would be the
> go I'm wondering how one might go about it.. I know that all iBGP
> neighbours must have a route to the peering IP of all other iBGP routers so
> I would assume an IGP must be run anyway???
- cisco say that
> anything more than 50 routers on an area is a bad idea, so if I have over
> 200 sites potentially on the VPLS, will OSPF cut it?
I guess i'm just
> trying to get my head around the different technology. I'd love to keep
> the stability that BGP brings, but also would like to be able to make use
> of the bandwidth that VPLS gives.
Any hints or tips will be gratefully
> received and thank you for any help. If you would like to keep from
> cluttering up subscriber's inboxes, please reply offlist.
Again, thanks
> for any help.
Regards,
Brad David
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