[MLB-WIRELESS] OSPF BGP

[Ryan Abbenhuys]

BGP (Border Gateway Protocol) is actually, as strange as this may seem....a
"Border Gateway Protocol". Meaning it is designed to run on the border of
network clusters (Autonomous Systems) to link them together.

For example, an ISP would use BGP to communicate routes (heavily aggregated
of course) out of their links to other ISP's, however within their own
building/network they will use OSPF, EIGRP, or similar.

To relate this to the Melbourne Wireless network, it would be like us using
BGP to link regional clusters together, while within the clusters using
OSPF.  This would work perfectly fine, although possibly a little overkill
due to extremely small size of our network, when compared to the internet,
OSPF should be quite sufficient.

So really the only people who would need to confuse themselves with
learning a second routing protocol would be those who are running the
backbone links between regional clusters.

As for the OSPF not functioning too well with everyone on area 0, that is
correct, it won't work too well.  Search through the mailing list archives,
I brought up this subject several times after a lot of research and
discussions with networking industry experts (who would normally charge a
LOT for their time) in an effort to steer people onto the right path,
although like IP allocations, with little success.



>I don't think there needs to be any sort of official "decision" to *test*
>BGP.  We're not scrapping OSPF - any testing I do will fully support
anyone
>who uses OSPF.
>
>At the moment we're not even using OSPF the way the Melbourne Wireless
>guidelines say we should.  Everyone I know of is using OSPF Area 0,
because
>experience shows that's the only way that properly works in our situation.
>When we use OSPF Area numbers, routing breaks because we don't connect to
>each other the way OSPF expects us to.  And we shouldn't have to.  We
should
>have a routing protocol that works for us the way we operate naturally. 
We
>shouldn't have to plan our links to fit the routing protocol.
>
>If we waited for official decisions to test new technologies and protocols
>we'd progress a lot slower than we already do.  If someone wants to try
>something out, they should do so - so long as it doesn't break the network
>for everybody else.  When the technology under test turns out to be a
better
>alternative than the current official standard, that's the time to weigh
the
>pros and cons and make a decision.
>
>Dan
>
>-----Original Message-----
>From: owner-melbwireless at wireless.org.au
>[mailto:owner-melbwireless at wireless.org.au] On Behalf Of Ryan Abbenhuys
>Sent: Wednesday, 22 June 2005 3:04 PM
>To: melbwireless at wireless.org.au
>Subject: Re: [MLB-WIRELESS] OSPF BGP
>
>
>Did I miss something?  Was the decision to use OSPF scrapped in favour of
>BGP?
>
>
>>http://www.melbourne.wireless.org.au/wiki/?BGP
>>
>>
>>ivile01 at yahoo.com.au | ivile at ivile.bur.st http://bur.st/~ivile 
>>(waveguides) | http://ivile.bur.st | http://ivile.bur.st/ivile/64/ (my 
>>car) http://www.melbourne.wireless.org.au/users/?ivile
>>----- Original Message -----
>>From: "Brenton D." <ivile01 at yahoo.com.au>
>>To: "Dan Flett" <conhoolio at hotmail.com>; "'Nigel'" 
>><thenigel at hotmail.com>;
>
>><melbwireless at wireless.org.au>
>>Sent: Wednesday, June 22, 2005 2:10 PM
>>Subject: Re: [MLB-WIRELESS] OSPF BGP
>>
>>
>>> Ill put up a really basic sample config. On the Wiki And ill have a 
>>> part where you can add your own asn.
>>> I was thinking that we should have a 5 number gap between each person
>BGP 
>>> asn, just in case they have more than one router(like me).
>>> so basically we have room for 1000 routers 64512 to 65534 which i 
>>> doubt there will be more than 50 running bgp in the near future.(as 
>>> some only support ospf)
>>>
>>> so node fut would have the bgp asn 64515 (just leave the first few
free)
>>>            fuu would have the bgp asn 64520
>>>            gho would have the bgp asn 64525 and so on...  unless you 
>>> have on the node page that they request a BGP
>>> asn(s)  from melb-wireless.
>>>
>>> ivile01 at yahoo.com.au | ivile at ivile.bur.st http://bur.st/~ivile 
>>> (waveguides) | http://ivile.bur.st | http://ivile.bur.st/ivile/64/ 
>>> (my car) http://www.melbourne.wireless.org.au/users/?ivile
>>> ----- Original Message -----
>>> From: "Dan Flett" <conhoolio at hotmail.com>
>>> To: "'Brenton D.'" <ivile01 at yahoo.com.au>; "'Nigel'" 
>>> <thenigel at hotmail.com>; <melbwireless at wireless.org.au>
>>> Sent: Wednesday, June 22, 2005 1:48 PM
>>> Subject: RE: [MLB-WIRELESS] OSPF BGP
>>>
>>>
>>>> So, Brenton, cutting it right down, your BGP file looks like this:
>>>>
>>>> !
>>>> hostname bgpd
>>>> password XXXXX
>>>> enable password XXXXX
>>>> !
>>>> router bgp 7675
>>>> bgp router-id 10.10.129.145
>>>> redistribute ospf
>>>> redistribute connected
>>>> !
>>>> ! DAN's COMMENTS: you probably don't need redistribute connected as 
>>>> you've
>>>> already declared your network
>>>> ! In Quagga the routing protocol automatically redistributes any
routes
>>>> declared with the network statement
>>>> ! Also, to be precise, the melbourne wireless network is entirely
>inside 
>>>> the
>>>> 10.10.0.0/16 supernet
>>>> !
>>>> network 10.0.0.0/8
>>>> neighbor 10.10.128.97 remote-as 7676
>>>> !
>>>> access-list all permit any
>>>> ! You probably don't need this access-list because you haven't
>specified 
>>>> any
>>>> route-maps
>>>> log stdout
>>>>
>>>>
>>>> That's as simple as a BGP file gets really - and if we weren't using
>OSPF
>>>> you could get rid of the redistribute ospf statement too.  You only
>need 
>>>> to
>>>> add neighbor lines each time you directly connect to a new BGP
>neighbor.
>>>> BGP gets complicated when you have multiple routes/routers/subnets
>within
>>>> the one AS.  If every node has their own AS it's quite easy.
>>>>
>>>> I'm considering writing a set of scripts that will automagically
create
>>>> Quagga/BGP config files from NVRAM variables or a very basic config
>file,
>>>> and that will exchange AS information with neighbors via DHCP.  So 
>>>> basically
>>>> you won't have to do anything (if you don't want to) except enter your
>IP
>>>> and AS addresses/numbers to start with.
>>>>
>>>> I'm thinking of running BGP at node GHO alongside OSPF.  We should let

>>>> GHO
>>>> settle and make sure it's stable for a few weeks before we try
>anything, 
>>>> but
>>>> I think it would be worth testing.
>>>>
>>>> How about someone create a BGP-Trial wiki page where we write down our
>AS
>>>> numbers for our nodes?  It should just be for testing, but it means we

>>>> can
>>>> test BGP in our own local clusters.  It doesn't matter if ASNs within
a
>>>> cluster are contiguous or not - that's the beauty of BGP - you can
>choose
>>>> any number you want, so long as it isn't someone else's.  We need to 
>>>> choose
>>>> our numbers from the IANA Private Use ASN space - being 64512 to
65534,
>>>> inclusive.
>>>>
>>>> Cheers,
>>>>
>>>> Dan
>>>
>>>
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>>
>>
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