Re: OSPF multi-level hierarchy: Necessary at all?
Well, you do know that you can create loopback interfaces and the router-ID will be the highest one among them. Say you do:
int lo 0 ip address 255.1.1.1
Hmm. Try yourself. Then, the quote from my config: ! interface Loopback98 description Router-ID ip address 223.255.254.118 255.255.255.255
I even proposed to declare 223.255/16 as private block -:).
Ah, yeah, forgot about the range :) but you got the idea.
network and name his _AREA 1.2.3.4_ with the strict filtering on the border.
I was thinking about it as well. One could configure some area range as a "discard" one, effectively saying that all routes dropping into the range should be ignored instead of announced in a summary-LSA. I am not sure if it's the same what I was saying, but approx. it is. We need good inter-area routing with the distribute-control over it. We can control exported prefixes by -STUB AREA- definition and/or summarisations, but we can't control incoming routes,
Mmmm...I believe you mean we can control imported (import/export...:)) hey, let's say external) routes with stub areas.
Btw, do you know _GATED_? It allow to control IMPORTED routes, but for OSPF_ASE_ routes only.
Actually in Cisco you can apply distribute-list to the whole process and it will be able to control which routes are installed into the routing table or got redistributed from it. You cannot control what is exchanged between routers, of course.
I don't think it's possible to control route import anywhere except area borders (for the OSPF case),
sure it is not, because you need to have syncronized LSDBs for all routers to calculate identical shortest paths.
but why don't do it on the area boundaries?
We should be able to but not now, unfortunately. I actualy have heard some rumors Cisco's gonna support this type of filtering.
This is reason why ISP don't like OSPF and such protocols - they can be used for the inter-router routing, but they can't be used to connect with the customers (no, I can run 10 different OSPF processes and re-advertise routes - one more headache for the network admins).
Actually, you can use NSSA, but doesn't allow for filtering either. Sorry, what's NSSA?
Not-So-Stubby Area, it works like a stub one, but allows to have an ASBR in it. So it does not accept ASE-LSAs from the domain, but can be used to inject externals into it.
PS. From ISP's point of view. What I'd like.
[snip: got your wish, Alex]
3) Moreover, why can't I determine different BGP AS numbers for the boths ISP and CUST OSPF zones.
who said you can't ? or I'm missing something? Yes, I can. But no one (except me) know about it -:).
I mean some mixturing of OSPF and BGP properties. They are mixtured already - OSPF tag can hold 1 BGP paths. Through I don't think it's important for now.
you mean RFC 1403? Alex. ------------------------------------------------------------------ Alex D. Zinin, Consultant CCSI #98966 CCIE #4015 AMT Group / ISL Cisco Systems Gold Certified Partner http://www.amt.ru irc: //EFNET/#cisco, //irc.msn.com/#NetCisco [Ustas]
Now I can say what I'd like to have. I'd like to have any way of inter-connection two DIFFERENT OSPF networks by such way that other network look like AREA (or STUB AREA) for the local network. This is: (the view of network admin A): -- Network-a - ABR1 -Area_1 (ABR - Area Border Router) For the admin-2 everything looks like: Area_2 -- ABR-2 - network-b Network admin 1 control Network-a with ABR-1, and define link to ABR-2 as usial link to the Area_1. Network admin 2 control network-b and define link to ABR-1 as the link to Area_2. Both Network-a and Network-b have their own backbones and the set of routers. moreover, to realise it, you need not new OSPF protocol, it can be implemented in ABR-1 and ABR-2. For now it can be modelled by running 'router ospf 1' and 'router ospf 2' on the same router, with the readvertising from one router to another, but it's configured by some tricky way and does not present network-b or network-a as an AREA (causeing some limitation and extra manual configurations).
I don't think it's possible to control route import anywhere except area borders (for the OSPF case),
sure it is not, because you need to have syncronized LSDBs for all routers to calculate identical shortest paths. Exactly.
Actually, you can use NSSA, but doesn't allow for filtering either. Sorry, what's NSSA? Oh, sorry, I know what;s it but did not read this abbreviation before.
Not-So-Stubby Area, it works like a stub one, but allows to have an ASBR in it. So it does not accept ASE-LSAs from the domain, but can be used to inject externals into it.
It's just the model of ISP-customer, btw.
ISP and CUST OSPF zones.
who said you can't ? or I'm missing something? Yes, I can. But no one (except me) know about it -:).
I mean some mixturing of OSPF and BGP properties. They are mixtured already - OSPF tag can hold 1 BGP paths. Through I don't think it's important for now.
you mean RFC 1403? Am not sure about # RFC, but yes - I mean this old schema when OSPF keep short BGP information - this was the way first OSPF/BGP networks was built by.
Alex. ------------------------------------------------------------------ Alex D. Zinin, Consultant CCSI #98966 CCIE #4015 AMT Group / ISL Cisco Systems Gold Certified Partner http://www.amt.ru irc: //EFNET/#cisco, //irc.msn.com/#NetCisco [Ustas]
Aleksei Roudnev, Network Operations Center, Relcom, Moscow (+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager) (+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)
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Alex Zinin