Failover how much complexity will it add?

adel at baklawasecrets.com adel at baklawasecrets.com
Sun Nov 8 15:39:33 CST 2009


Hi,

Ok thanks for clearing that up.  I'm getting some good feedback on applying for PI and ASN through Ripe LIRs over on the UKNOF so I think I have a handle on this.
With regards to BGP and using separate BGP routers.  I am announcing my PI space to my upstreams, but I don't need to carry a full Internet routing table, correct?
So I can get away with some "lightweight" BGP routers not being an ISP if that makes sense?

Adel



On Sun   9:26 PM , Ken Gilmour <ken.gilmour at gmail.com> wrote:

> Hey,
> 
> Yes you apply to RIPE for your allocation. You should ask them for a
> /20 since it's the same price for that as a /24 if you can justify it
> (at least with LACNIC where i now get my allocations)...
> 
> You will also need to apply for an ASN
> 
> Correct- the block belongs to you and as long as you contact the
> transit provider from the address listed in WHOIS then you should be
> able to set up a new agreement easily.
> 
> Yes the block is PI space (provider independent)
> 
> It can take up to 1 month to get your assignments.
> 
> I would recommend getting some different routers for this. I use
> OpenBSD in some of my locations which is extremely easy to work with.
> I also have some old NS-208 devices running ScreenOS for internal BGP
> in one other location. I would not recommend using any router with
> less than 1GB of RAM for BGP. in HA Mode you can connect the two
> tails, one to each SSG (if they are in active active mode) and
> announce it that way (check out anycast), we also do this :).
> 
> The way BGP works is that both connections are active at the same
> time, there is no primary and backup, if one goes down you just have
> one less to receive traffic over and more traffic on the other, but
> unless you stop announcing from one connection traffic will go over
> both.
> 
> Regards,
> 
> Ken
> 
> 2009/11/8 :
> > Don't think I sent the below to the list, so resending:
> >
> > Thanks Seth and James,
> >
> >  Things are getting a lot clearer.  The BGP multihoming solution
> sounds like exactly what I want.  I have more questions :-)
> >
> > Now I suppose I would get my allocation from RIPE as I am UK based?
> >
> > Do I also need to apply for an AS  number?
> >
> > As the IP block is "mine", it is ISP  independent.  i.e. I can take
> it with me when I decide to use two
> > completely different ISPs?
> >
> >  Is the obtaining of this IP block, what is referred to as PI space?
> >
> > Of course internally I split the /24 up however  I want - /28 for
> untrust range and maybe a routed DMZ block
> >  etc.?
> >
> > Assuming I apply for IP block and AS number, whats involved and how
> long does it take to get these babies?>
> >
> > I know the SSG550's have BGP capabilites.  As I have two of these in
> HA mode, does it make sense to do the BGP
> >  on these, or should I get dedicated BGP routers?
> >
> >  Fixing the internal routing policy so traffic is  directed at the
> active BGP connection.  Whats involved here,
> >  preferring one BGP link over the other?
> >
> >  Thanks again, I obviously need to do some  reading of my own, but
> all the suggestions so far have been very valuable
> >  and definitely seem to be pointing in some fruitful directions.
> >
> >  Adel
> >
> >
> >
> >
> > On Sun   6:31 PM , James Hess  wrote:
> >
> >> On Sun, Nov 8, 2009 at 11:34 AM,  wrote:
> >> [..]
> >> > connections from different providers I would still have issues.  So
> >> > I guess that if my primary Internet goes down I lose connectivity
> >> > to all the publicly addressed devices on that connection. Like
> >> > dmz hosts and so on.  I would be interested to hear how this
> >> > can be avoided if at all or do I have to use the same provider.
> >>
> >> You assign multi-homed IP address space to your publicly addressed
> >> devices,
> >> which are not specific to either ISP. You announce to both ISPs, and
> >> you accept some routes from both ISPs.
> >>
> >> You get multi-homed IPs, either by having an existing ARIN allocation,
> >> or getting a /22 from ARIN (special allocation available for
> >> multi-homing), or ask for a /24 from ISP A or ISP B for
> >> multihoming.
> >>
> >> If Link A fails, the BGP session eventually times out and dies: ISP
> >> A's BGP routers withdraw the routes, the IP addresses are then
> >> associated only with provider B.
> >>
> >> And you design your internal routing policy to direct traffic
> >> within your network to the router with an active BGP session.
> >>
> >> Link A's failure is _not_ a total non-event, but a 3-5 minute partial
> >> disruption, while the BGP session times out and updates occur in other
> >> people's routers, is minimal compared to a 3 day outage, if serious
> >> repairs to upstream fiber are required.
> >>
> >> --
> >> -J
> >>
> >>
> >>
> >
> >
> 
> 
> 




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