Mailing List Archive: Problems with OSPF stub area (Juniper and Cisco)

Problems with OSPF stub area (Juniper and Cisco)

Nov 4, 2002, 11:06 PM

Post #1 of 9 (4581 views)

Hi,

I'm having problems with configuring an OSPF stub area where ABR is
Juniper (JUNOS 5.4.R2.4) and inside the area there is a Cisco router.
The routers are connected to each other over an ATM PVC.

Currently, I have the following configuration in Juniper:

interfaces {
at-0/0/0 {
unit 206 {
encapsulation atm-snap;
vci 0.206;
inverse-arp;
family inet {
rpf-check;
no-redirects;
address 193.166.187.205/30;
}
}
}
}

protocols {
ospf {
area 193.167.206.0 {
stub default-metric 10 no-summaries;
area-range 193.167.206.0/25;
area-range 193.166.187.204/30;
interface at-0/0/0.206;
}
}
}

I've no access to the Cisco router on the other end of the link. Yet,
I think its configuration is more or less in order because when I had
a Cisco router in place of the Juniper there were no problems. In
Cisco, the following configuration did work:

interface ATM8/0/0.6 point-to-point
ip address 193.166.187.205 255.255.255.252
ip verify unicast reverse-path
no ip directed-broadcast
ip pim sparse-dense-mode
ip ospf network broadcast
atm pvc 206 0 206 aal5snap inarp
no atm enable-ilmi-trap
router ospf 1739
area 193.167.206.0 stub no-summary
area 193.167.206.0 range 193.167.206.0 255.255.255.128
network 193.166.187.204 0.0.0.3 area 193.167.206.0
network 193.167.206.0 0.0.0.127 area 193.167.206.0

While looking through the ospf trace in Juniper I don't see anything
about the network 193.167.206.0. Only the /30 in p2p link shows up.
The adjacency between Juniper and Cisco becomes full and in the area
database I can see the routes. Still, they never appear in the
forwarding table.

So, if anyone can give me any hints what to do or what I do wrong,
I'll appreciate it.

Cheers,

--
Matti Saarinen, Tampere University of Technology / Network Administration
Phone: +358 3 3115 3337 # Address: P.O. Box 692
Fax: +358 3 3115 2172 # FIN-33101 Tampere
Email: mjs@cc.tut.fi # Finland

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

pekkas at netcore

Nov 4, 2002, 11:52 PM

Post #2 of 9 (4538 views)

Permalink

On 5 Nov 2002, Matti Saarinen wrote:
> area 193.167.206.0 {
> stub default-metric 10 no-summaries;
> area-range 193.167.206.0/25;
> area-range 193.166.187.204/30;
> interface at-0/0/0.206;
> }

Compare to:

> area 193.167.206.0 stub no-summary
> area 193.167.206.0 range 193.167.206.0 255.255.255.128
> network 193.166.187.204 0.0.0.3 area 193.167.206.0
> network 193.167.206.0 0.0.0.127 area 193.167.206.0

I note that you didn't have the P-t-P address in the area-range in Cisco,
but now have in Juniper.

Perhaps that has something to do with it..

--
Pekka Savola "Tell me of difficulties surmounted,
Netcore Oy not those you stumble over and fall"
Systems. Networks. Security. -- Robert Jordan: A Crown of Swords

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

mjs at cc

Nov 5, 2002, 12:15 AM

Post #3 of 9 (4569 views)

Permalink

Pekka Savola <pekkas@netcore.fi> writes:

> > area-range 193.167.206.0/25;
> > area-range 193.166.187.204/30;
>
> > area 193.167.206.0 stub no-summary
> > area 193.167.206.0 range 193.167.206.0 255.255.255.128
> > network 193.166.187.204 0.0.0.3 area 193.167.206.0
> > network 193.167.206.0 0.0.0.127 area 193.167.206.0
>
> I note that you didn't have the P-t-P address in the area-range in
> Cisco, but now have in Juniper.

I've tried the stub area without any ranges, with only the range
193.167.206.0/25 and with both. The result has been the same. The
/25 route doesn't appear in the Juniper's forwarding table.

--
Matti Saarinen, Tampere University of Technology / Network Administration
Phone: +358 3 3115 3337 # Address: P.O. Box 692
Fax: +358 3 3115 2172 # FIN-33101 Tampere
Email: mjs@cc.tut.fi # Finland

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

avram at juniper

Nov 5, 2002, 7:35 AM

Post #4 of 9 (4558 views)

Permalink

Hey Matti,

I tried this config between two junipers, and at first the /25 did not
show up either, but it shouldn't have - there were no more specific
active routes from the range to coalesce.

Then I added a 193.167.206.16/30 hanging off of the "cisco" in your
scenario, and both it and the /25 discard route showed up on both
routers.

Do you have such a subordinate route actually in your area?

(As a side note, I don't see how you got your ATM interface to come up
without having specified the atm-options vpi 0 max-vcs statement, or
did you just omit it from your email?)

-Avram

On Tuesday, November 5, 2002, at 02:06 AM, Matti Saarinen wrote:

>
> Hi,
>
> I'm having problems with configuring an OSPF stub area where ABR is
> Juniper (JUNOS 5.4.R2.4) and inside the area there is a Cisco router.
> The routers are connected to each other over an ATM PVC.
>
>
> Currently, I have the following configuration in Juniper:
>
>
> interfaces {
> at-0/0/0 {
> unit 206 {
> encapsulation atm-snap;
> vci 0.206;
> inverse-arp;
> family inet {
> rpf-check;
> no-redirects;
> address 193.166.187.205/30;
> }
> }
> }
> }
>
> protocols {
> ospf {
> area 193.167.206.0 {
> stub default-metric 10 no-summaries;
> area-range 193.167.206.0/25;
> area-range 193.166.187.204/30;
> interface at-0/0/0.206;
> }
> }
> }
>
>
> I've no access to the Cisco router on the other end of the link. Yet,
> I think its configuration is more or less in order because when I had
> a Cisco router in place of the Juniper there were no problems. In
> Cisco, the following configuration did work:
>
>
> interface ATM8/0/0.6 point-to-point
> ip address 193.166.187.205 255.255.255.252
> ip verify unicast reverse-path
> no ip directed-broadcast
> ip pim sparse-dense-mode
> ip ospf network broadcast
> atm pvc 206 0 206 aal5snap inarp
> no atm enable-ilmi-trap
> router ospf 1739
> area 193.167.206.0 stub no-summary
> area 193.167.206.0 range 193.167.206.0 255.255.255.128
> network 193.166.187.204 0.0.0.3 area 193.167.206.0
> network 193.167.206.0 0.0.0.127 area 193.167.206.0
>
>
> While looking through the ospf trace in Juniper I don't see anything
> about the network 193.167.206.0. Only the /30 in p2p link shows up.
> The adjacency between Juniper and Cisco becomes full and in the area
> database I can see the routes. Still, they never appear in the
> forwarding table.
>
> So, if anyone can give me any hints what to do or what I do wrong,
> I'll appreciate it.
>
> Cheers,
>
>
> --
> Matti Saarinen, Tampere University of Technology / Network
> Administration
> Phone: +358 3 3115 3337 # Address: P.O. Box 692
> Fax: +358 3 3115 2172 # FIN-33101 Tampere
> Email: mjs@cc.tut.fi # Finland
>
> _______________________________________________
> juniper-nsp mailing list juniper-nsp@puck.nether.net
> http://puck.nether.net/mailman/listinfo/juniper-nsp

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

mjs at cc

Nov 5, 2002, 10:31 PM

Post #5 of 9 (4562 views)

Permalink

Avram Dorfman <avram@juniper.net> writes:

> I tried this config between two junipers, and at first the /25 did not
> show up either, but it shouldn't have - there were no more specific
> active routes from the range to coalesce.
>
> Then I added a 193.167.206.16/30 hanging off of the "cisco" in your
> scenario, and both it and the /25 discard route showed up on both
> routers.
>
> Do you have such a subordinate route actually in your area?

Hi

No, I don't have such a route. But, now I looked at Cisco's
configuration again and noticed the the following command
under the atm interface's configuration.

ip ospf network broadcast

When I remove the command the /25 route disappears from the
routing table. So, I think there's the problem. I couldn't find
the similar configuration statement under Juniper's OSPF
configuration. Is there any way to configure the similar
functionality in JUNOS? I mean that the way OSPF sees the ATM
interface should be broadcast instead of point-to-point.

> (As a side note, I don't see how you got your ATM interface to come up
> without having specified the atm-options vpi 0 max-vcs statement, or
> did you just omit it from your email?)

Yes, I did omit it from my email.

Cheers,

--
Matti Saarinen, Tampere University of Technology / Network Administration
Phone: +358 3 3115 3337 # Address: P.O. Box 692
Fax: +358 3 3115 2172 # FIN-33101 Tampere
Email: mjs@cc.tut.fi # Finland

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

avram at juniper

Nov 6, 2002, 7:34 AM

Post #6 of 9 (4573 views)

Permalink

I believe that makes it pretend that the interface is a broadcast,
causing a different representation in the LSDP, DR election, and type2
LSA generation, etc. We can let you set the interface to NBMA or P2MP,
but not broadcast. I'm a little surprised the adjacency became full,
with the two routers disagreeing on the link type. I'd love to see the
router LSA's for those two routers, while that command is active.

I suspect the fact that it causes the cisco to coalesce an unused range
is an unintended feature. What you are suggesting is essentially
abusing an unrelated aspect of the protocol to trigger a side effect of
coalescing routes that you don't have.

I suggest that you are better off having the routes. Can you add a /32
from the range to a loopback somewhere? More importantly, why do you
need this route in OSPF if there are no destinations from it in the
area? Perhaps there is a more natural way to affect your desired
behavior.

-Avram
Juniper Pro Services

On Wednesday, November 6, 2002, at 01:31 AM, Matti Saarinen wrote:

> Avram Dorfman <avram@juniper.net> writes:
>
>
>> I tried this config between two junipers, and at first the /25 did not
>> show up either, but it shouldn't have - there were no more specific
>> active routes from the range to coalesce.
>>
>> Then I added a 193.167.206.16/30 hanging off of the "cisco" in your
>> scenario, and both it and the /25 discard route showed up on both
>> routers.
>>
>> Do you have such a subordinate route actually in your area?
>
> Hi
>
> No, I don't have such a route. But, now I looked at Cisco's
> configuration again and noticed the the following command
> under the atm interface's configuration.
>
> ip ospf network broadcast
>
> When I remove the command the /25 route disappears from the
> routing table. So, I think there's the problem. I couldn't find
> the similar configuration statement under Juniper's OSPF
> configuration. Is there any way to configure the similar
> functionality in JUNOS? I mean that the way OSPF sees the ATM
> interface should be broadcast instead of point-to-point.
>
>
>> (As a side note, I don't see how you got your ATM interface to come up
>> without having specified the atm-options vpi 0 max-vcs statement, or
>> did you just omit it from your email?)
>
> Yes, I did omit it from my email.
>
>
> Cheers,
>
> --
> Matti Saarinen, Tampere University of Technology / Network
> Administration
> Phone: +358 3 3115 3337 # Address: P.O. Box 692
> Fax: +358 3 3115 2172 # FIN-33101 Tampere
> Email: mjs@cc.tut.fi # Finland
>

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

mjs at cc

Nov 7, 2002, 10:50 PM

Post #7 of 9 (4535 views)

Permalink

Avram Dorfman <avram@juniper.net> writes:

> On Wednesday, November 6, 2002, at 01:31 AM, Matti Saarinen wrote:
>
> > No, I don't have such a route. But, now I looked at Cisco's
> > configuration again and noticed the the following command
> > under the atm interface's configuration.
> >
> > ip ospf network broadcast
>
> I believe that makes it pretend that the interface is a broadcast,
> causing a different representation in the LSDP, DR election, and
> type2 LSA generation, etc.

Yes, that's what it does.

> I'm a little surprised the adjacency became full, with the two
> routers disagreeing on the link type.

So am I. Unfortunately I cannot check the configuration the Cisco
at the other end of the ATM PVC has but I think it must have the
same conf as the Cisco at our end has eg. ip ospf netowrk
broadcast. I did set up a similar configuration just to debug
things. When the Cisco I used had interface configured as
broadcast the OSPF adjcency state machine got stuck at the
ExStart state. Everything worked fine when I removed the
broadcast statement.

> I'd love to see the router LSA's for those two routers, while that
> command is active.

I can try to capture that for you. I already contacted the
university who administrates that router and asked them to check
their configuration. It is always possible that there's a some
soft of software bug which doesn't show up between two Ciscos.

> I suggest that you are better off having the routes. Can you add a
> /32 from the range to a loopback somewhere? More importantly, why do
> you need this route in OSPF if there are no destinations from it in
> the area?

I'm sorry but I don't understand. There is a /25 which belongs to
that area and it doesn't show up in the forwarding table. That's
the problem I have. I'm sure it'll go away when somebody checks
the Ciscos configuration.

Cheers and thanks,

--
Matti Saarinen, Tampere University of Technology / Network Administration
Phone: +358 3 3115 3337 # Address: P.O. Box 692
Fax: +358 3 3115 2172 # FIN-33101 Tampere
Email: mjs@cc.tut.fi # Finland

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

avram at juniper

Nov 8, 2002, 7:19 AM

Post #8 of 9 (4557 views)

Permalink

Hey Matti,

>> I suggest that you are better off having the routes. Can you add a
>> /32 from the range to a loopback somewhere? More importantly, why do
>> you need this route in OSPF if there are no destinations from it in
>> the area?
>
> I'm sorry but I don't understand. There is a /25 which belongs to
> that area and it doesn't show up in the forwarding table. That's
> the problem I have. I'm sure it'll go away when somebody checks
> the Ciscos configuration.
>

You're trying to get an ABR to "coalesce" (i.e. summarize, or
aggregate, but coalesce is the OSPF RFC term) routes. In other words,
you want to have multiple longer-mask routes in the range
193.167.206.0/25, in the stub area, but you only want to see the
coalesced (or "aggregated") route outside the area.

Earlier in this thread, when I asked if the ABR actually /had/ any
longer-mask routes in the range, you said it did not. We only coalesce
routes if there are routes to coalesce. If there are no more specific
OSPF routes in the area to coalesce, then there should be no need for
the /25 route in OSPF either, so we don't generate it.

So, I asked why you need such a route to be in OSPF in the first place.
If you do, I suggested that you should somehow ensure that there really
is a more specific route from the range in the area. Otherwise, you
should be looking at either exporting a route into OSPF, or perhaps you
are also running BGP, and you could deal with this route there.

Sorry if my use of the word "coalesce" is confusing. People often call
it summarizing, but that's not accurate when discussing OSPF, b/c it
refers to generating type 3 and type 4 LSAs for other areas, which does
not imply aggregation.

-Avram

Problems with OSPF stub area (Juniper and Cisco) [ In reply to ]

mjs at cc

Nov 17, 2002, 2:09 AM

Post #9 of 9 (4560 views)

Permalink

Avram Dorfman <avram@juniper.net> writes:

> You're trying to get an ABR to "coalesce" (i.e. summarize, or
> aggregate, but coalesce is the OSPF RFC term) routes. In other
> words, you want to have multiple longer-mask routes in the range
> 193.167.206.0/25, in the stub area, but you only want to see the
> coalesced (or "aggregated") route outside the area.

Hi

[ Sorry for the delay in replying ]

Actually, I thought that wouldn't be the case but it is. There
are multiple loger-mask routes in the area. The problem was that
I saw _no_ routes in the area. Well, the /30 used on the p2p link
did show up but not the others.

> So, I asked why you need such a route to be in OSPF in the first
> place. If you do, I suggested that you should somehow ensure that
> there really is a more specific route from the range in the area.
> Otherwise, you should be looking at either exporting a route into
> OSPF, or perhaps you are also running BGP, and you could deal with
> this route there.

OSPF is the only way our router learns the routes in the area.
Well, not the only way. There is always the possibility of using
static routes but it's ugly.

At the moment, the routes do show up. The solution was to change
the Cisco's configuration in a way that it sees the ATM
connection as a point-to-point link, too. I do still wonder how
on earth the neighbour adjacency became Full in the beginning
when the routers saw different link types.

> Sorry if my use of the word "coalesce" is confusing. People often call
> it summarizing, but that's not accurate when discussing OSPF, b/c it
> refers to generating type 3 and type 4 LSAs for other areas, which
> does not imply aggregation.

It's okay. I'm the one who should have understood. It's just been
a long time since I've last checked the OSPF RFCs or the Moy's
book. Now, I do remember the term.

Thanks a lot again.

--
- Matti -