Subject: [OSPF] Route Calculation for Type-5 LSA (default route)

From: "Jishnu Banerjee" <[email-masked]>
Date: Mon, 27 Aug 2007 18:41:10 +0530

Hi All, 

I have a doubt related to OSPF route selection : (Please refer to the
topology below)

                             R1--------Ethernet-------R2

                               \                                /

                                 \                            /

                                    \                       /

                               Gig0 \___________/Gig1

                                       |____R3____|

The router to be considered is R3. This R3 receives multiple External
Type-1 LSAs due to "default-originate" being used on remote routers
which lie beyond R1 & R2. Router R3 establishes adjacency with R1 and R2
on two different broadcast segments.

Now the ospf database on R3 shows that it has learnt 0.0.0.0 from six
(6) different Advertising routers and also each of there Forwarding
Address Field is NON-zero address. The detailed display of the LSA shows
that all are of the same Metric Type i.e. E1 and of same Metric Value
i.e.6

Out of 6, three of Advertising routers and their corresponding
Forwarding Address are reachable via Gig0 while the rest of Advertising
Routers and their corresponding Forwarding Address are reachable via
Gig1. OSPF interface cost on both Gig1 and Gig0 are equal (1)

Now the questions are: 

1.	In the above situation, when 0.0.0.0 needs to be installed in
the Routing Table as OE2 route, then will it appear with two next-hops
(both Gig0 & Gig1) or it shall appear only on one next-hop (either Gig1
or Gig0) ? The behavior that I am seeing in router R3 is that ==> Route
Table has installed 0.0.0.0 as OE2 with nexthop on Gig1. Is this a
correct behavior?

2.      Moreover I want to know whether Section 12.4.4 & Page 140-141
(RFC 2328), which says "The following rule is thereby established: if
two routers, both reachable from one another, originate functionally
equivalent AS-external-LSAs (i.e., same destination, cost and non-zero
forwarding address), then the LSA originated by the router having the
highest OSPF Router ID is used." is applicable in this situation or not
? 
3.      If #2 is applicable to the above situation, then correct my
deduction if I am wrong, as mentioned below: 

I found that Advertising Router with highest router-id and its
forwarding address are ONLY REACHABLE via Gig1. Thus the 0.0.0.0 gets
installed with nexthop as Gig1 in the routing table

I would really appreciate your help.

Regards,

Jishnu

FYI, I am just adding the database log: (from router R3)

show ip ospf database external 0.0.0.0

            OSPF Router with ID (202.87.37.225) (Process ID 10)

                Type-5 AS External Link States

  LS age: 1355

  Options: (No TOS-capability, No DC)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 123.108.37.253

  LS Seq Number: 80000082

  Checksum: 0x1B87

  Length: 36

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

        Forward Address: 123.108.37.17

        External Route Tag: 0

  LS age: 1294

  Options: (No TOS-capability, No DC)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 123.108.37.254

  LS Seq Number: 80000083

  Checksum: 0x327E

  Length: 36

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

        Forward Address: 123.108.37.1

        External Route Tag: 0

  LS age: 1284

  Options: (No TOS-capability, No DC)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 124.153.97.253

  LS Seq Number: 80000084

  Checksum: 0x8E49

  Length: 36

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

        Forward Address: 124.153.97.5

        External Route Tag: 0

  LS age: 1183

  Options: (No TOS-capability, No DC)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 124.153.97.254

  LS Seq Number: 80000082

  Checksum: 0xC410

  Length: 36

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

        Forward Address: 124.153.97.9

        External Route Tag: 0

  LS age: 1217

  Options: (No TOS-capability, No DC)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 202.87.37.230

  LS Seq Number: 80000696

  Checksum: 0x5DE8

  Length: 36

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

        Forward Address: 59.163.24.70

        External Route Tag: 0

  LS age: 1358

  Options: (No TOS-capability, No DC)

  LS Type: AS External Link

  Link State ID: 0.0.0.0 (External Network Number )

  Advertising Router: 202.87.37.231

  LS Seq Number: 80000085

  Checksum: 0xF858

  Length: 36

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

        Forward Address: 219.64.42.2

        External Route Tag: 0

show ip ospf  neighbor

Process ID 10

Neighbor ID     Pri   State              Dead Time   Address
Interface

202.87.37.231     1   FULL/DR            00:00:31    202.87.37.165
gigabitethernet1

202.87.37.230     1   FULL/DR            00:00:39    202.87.37.161
gigabitethernet0

show ip ospf interface

gigabitethernet1 is up, line protocol is up

  Internet Address 202.87.37.166/30, Area 1

  Process ID 10, Router ID 202.87.37.225, Network Type BROADCAST, Cost:
1

  Transmit Delay is 1 sec, State BDR, Priority 1

  Designated Router (ID) 202.87.37.231, Intf address 202.87.37.165

  Backup Designated router (ID) 202.87.37.225, Intf address
202.87.37.166

  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

    Hello due in 00:00:03

  Neighbor Count is 1, Adjacent neighbor count is 1

    Adjacent with neighbor 202.87.37.231  (Designated Router)

  Suppress hello for 0 neighbor(s)

  Message digest authentication enabled

gigabitethernet0 is up, line protocol is up

  Internet Address 202.87.37.162/30, Area 1

  Process ID 10, Router ID 202.87.37.225, Network Type BROADCAST, Cost:
1

  Transmit Delay is 1 sec, State BDR, Priority 1

  Designated Router (ID) 202.87.37.230, Intf address 202.87.37.161

  Backup Designated router (ID) 202.87.37.225, Intf address
202.87.37.162

  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

    Hello due in 00:00:03

  Neighbor Count is 1, Adjacent neighbor count is 1

    Adjacent with neighbor 202.87.37.230  (Designated Router)

  Suppress hello for 0 neighbor(s)

  Message digest authentication enabled

loopback1 is up, line protocol is up

  Internet Address 202.87.37.225/32, Area 1

  Process ID 10, Router ID 202.87.37.225, Network Type LOOPBACK, Cost:
1000

  Loopback interface is treated as a stub Host

show ip route  ospf

Codes: R - RIP, O - OSPF, C - connected, S - static

       IA - OSPF inter area route, E1 - OSPF external type 1 route,

       E2 - OSPF external type 2 route, N1 - OSPF NSSA external type 1
route,

       N2 - OSPF NSSA external type 2 route

       * - candidate default route

O*E1 0.0.0.0/0 [110/8][10] via 202.87.37.165, gigabitethernet1

_______________________________________________
OSPF mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/ospf

---

From: Acee Lindem <[email-masked]>
Date: Mon, 27 Aug 2007 09:35:11 -0400

Jishnu,
In the future, can you condense your questions down to specific  
protocol questions? This is not a forum for us to debug your network.  
See inline.

On Aug 27, 2007, at 9:11 AM, Jishnu Banerjee wrote:

> Hi All,
>
> I have a doubt related to OSPF route selection : (Please refer to  
> the topology below)
>
>
>
>
>
> The router to be considered is R3. This R3 receives multiple  
> External Type-1 LSAs due to “default-originate” being used on  
> remote routers which lie beyond R1 & R2. Router R3 establishes  
> adjacency with R1 and R2 on two different broadcast segments.
>
> Now the ospf database on R3 shows that it has learnt 0.0.0.0 from  
> six (6) different Advertising routers and also each of there  
> Forwarding Address Field is NON-zero address. The detailed display  
> of the LSA shows that all are of the same Metric Type i.e. E1 and  
> of same Metric Value i.e.6
>
> Forwarding Address are reachable via Gig0 while the rest of  
> Advertising Routers and their corresponding Forwarding Address are  
> reachable via Gig1. OSPF interface cost on both Gig1 and Gig0 are  
> equal (1)
>
>
>
> Now the questions are:
>
> In the above situation, when 0.0.0.0 needs to be installed in the  
> Routing Table as OE2 route, then will it appear with two next-hops  
> (both Gig0 & Gig1) or it shall appear only on one next-hop (either  
> Gig1 or Gig0) ? The behavior that I am seeing in router R3 is that  
> è Route Table has installed 0.0.0.0 as OE2 with nexthop on Gig1. Is  
> this a correct behavior?
You must be looking at a different network. Your 6 candidate LSAs  
have type 1 metric. Why would you expect a type 2 external route to  
be installed.

> 2.      Moreover I want to know whether Section 12.4.4 & Page  
> 140-141 (RFC 2328), which says “The following rule is thereby  
> established: if two routers, both reachable from one another,  
> originate functionally equivalent AS-external-LSAs (i.e., same  
> destination, cost and non-zero forwarding address), then the LSA  
> originated by the router having the highest OSPF Router ID is  
> used.” is applicable in this situation or not ?
No - all the candidate LSAs have different forwarding addresses.   
Hence, they are not equivalent.

Acee

> forwarding address are ONLY REACHABLE via Gig1. Thus the 0.0.0.0  
> gets installed with nexthop as Gig1 in the routing table
>
>
>
> Neighbor ID     Pri   State              Dead Time    
> Address         Interface
>
> 202.87.37.231     1   FULL/DR            00:00:31     
> 202.87.37.165   gigabitethernet1
>
> 202.87.37.230     1   FULL/DR            00:00:39     
> 202.87.37.161   gigabitethernet0
>
>
>
> show ip ospf interface
>
>   Process ID 10, Router ID 202.87.37.225, Network Type BROADCAST,  
> Cost: 1
>
>   Process ID 10, Router ID 202.87.37.225, Network Type BROADCAST,  
> Cost: 1
>
>   Process ID 10, Router ID 202.87.37.225, Network Type LOOPBACK,  
> Cost: 1000
>
>        E2 - OSPF external type 2 route, N1 - OSPF NSSA external  
> type 1 route,
>

---

From: "Jishnu Banerjee" <[email-masked]>
Date: Mon, 27 Aug 2007 19:36:44 +0530

Hi Acee,

I apologize for the doubt being presented to forum in verbose. In
future, shall certainly take care of that.

Coming back to the question: Referring to question 1, I misquoted it as
Type 2 instead of Type 1. It is actually a OE1 route in routing table

As Section 12.4.4 is not applicable in this situation, so can I expected
the during SPF calculation each of these LSA will be considered (since
each of the advertsing routers are reachable) and thus ECMP on OSPF
route will get exhibited i.e.0.0.0.0 being learnt on multiple nexthops

-jishnu

________________________________

From: Acee Lindem [mailto:[email-masked]] 
Sent: Monday, August 27, 2007 7:05 PM
To: Jishnu Banerjee
Cc: [email-masked]; Soman K. S
Subject: Re: Route Calculation for Type-5 LSA (default route)

Jishnu,

In the future, can you condense your questions down to specific protocol
questions? This is not a forum for us to debug your network. See inline.

                               \                                /

                                    \                       /

                                       |____R3____|

Now the questions are:

1.	Route Table has installed 0.0.0.0 as OE2 with nexthop on Gig1.
Is this a correct behavior?

You must be looking at a different network. Your 6 candidate LSAs have
type 1 metric. Why would you expect a type 2 external route to be
installed. 

1.	2.Moreover I want to know whether Section 12.4.4 & Page 140-141
(RFC 2328), which says "The following rule is thereby established: if
two routers, both reachable from one another, originate functionally
equivalent AS-external-LSAs (i.e., same destination, cost and non-zero
forwarding address), then the LSA originated by the router having the
highest OSPF Router ID is used.

Jishnu

  LS age: 1355

  Checksum: 0x1B87

  Network Mask: /0

        TOS: 0

  LS Seq Number: 80000083

  Length: 36

        Metric Type: 1

        Metric: 6

        External Route Tag: 0

  LS age: 1284

  Checksum: 0x8E49

  Network Mask: /0

        TOS: 0

  LS Seq Number: 80000082

  Length: 36

        Metric Type: 1

        Metric: 6

        External Route Tag: 0

  LS age: 1217

  Checksum: 0x5DE8

  Network Mask: /0

        TOS: 0

  LS Seq Number: 80000085

  Length: 36

        Metric Type: 1

        Metric: 6

        External Route Tag: 0

show ip ospf  neighbor

Process ID 10

show ip route  ospf

---

From: Acee Lindem <[email-masked]>
Date: Mon, 27 Aug 2007 10:11:15 -0400

Hi Jishnu,

On Aug 27, 2007, at 10:06 AM, Jishnu Banerjee wrote:

> Coming back to the question: Referring to question 1, I misquoted  
> it as Type 2 instead of Type 1. It is actually a OE1 route in  
> routing table
>
> As Section 12.4.4 is not applicable in this situation, so can I  
> expected the during SPF calculation each of these LSA will be  
> considered (since each of the advertsing routers are reachable) and  
> thus ECMP on OSPF route will get exhibited i.e.0.0.0.0 being learnt  
> on multiple nexthops
I would say that depends on whether the longest match OSPF route to  
forwarding address is an ECMP route. If it is, than yes I'd expect  
the OSPF External Type 1 route to be ECMP. Look at section 16.4 in  
RFC 2328 and it is clear that the route should be inherited from the  
forwarding address route.

Acee

> protocol questions? This is not a forum for us to debug your  
> network. See inline.
>
>
>
> Route Table has installed 0.0.0.0 as OE2 with nexthop on Gig1. Is  
> this a correct behavior?
> 2.Moreover I want to know whether Section 12.4.4 & Page 140-141  
> (RFC 2328), which says “The following rule is thereby established:  
> if two routers, both reachable from one another, originate  
> functionally equivalent AS-external-LSAs (i.e., same destination,  
> cost and non-zero forwarding address), then the LSA originated by  
> the router having the highest OSPF Router ID is used.
>
>
>
>
>
> Jishnu
>

---

From: "Jishnu Banerjee" <[email-masked]>
Date: Tue, 28 Aug 2007 09:21:55 +0530

How about a situation like this ==>

If same LSA (metric type E1 and metric being same) has been advertised
by two different ASBRs, each having non-zero fwding address, then as per
section 16.4, I find the following :

1.	Both ASBRs are reachable. Route to ASBR A1 is via nexthop on
interface IF1 while ASBR A2 is via nexthop on interface IF2. Both route
entries are of the same cost and both their associated area being the
same, subsequently the AS-paths to ASBR are of equal preference being
Inter-area paths.
2.	Considering the Fwd Address for the above ASBRs, if both of Fwd
Address (one on each ASBR) happens to be reachable in the same pattern
as above, then how do we break the tie ? 

On which interface should we expect the network (in this case 0.0.0.0)
should get resolved as OSPF E1 ?

Thanks Jishnu

From: Acee Lindem [mailto:[email-masked]] 
Sent: Monday, August 27, 2007 7:41 PM
To: Jishnu Banerjee
Cc: [email-masked]
Subject: Re: Route Calculation for Type-5 LSA (default route)

Hi Jishnu,

Hi Acee,

I would say that depends on whether the longest match OSPF route to
forwarding address is an ECMP route. If it is, than yes I'd expect the
OSPF External Type 1 route to be ECMP. Look at section 16.4 in RFC 2328
and it is clear that the route should be inherited from the forwarding
address route. 

Acee

-jishnu

From: Acee Lindem [mailto:[email-masked]] 
Sent: Monday, August 27, 2007 7:05 PM
To: Jishnu Banerjee
Cc: [email-masked] <mailto:[email-masked]> ; Soman K. S
Subject: Re: Route Calculation for Type-5 LSA (default route)

Jishnu,

 

 

                                    \                       /

Now the questions are:

  LS age: 1355

  Network Mask: /0

  LS Seq Number: 80000083

        Metric Type: 1

        External Route Tag: 0

  Checksum: 0x8E49

        TOS: 0

  Length: 36

        Metric: 6

  LS age: 1217

  Network Mask: /0

  LS Seq Number: 80000085

        Metric Type: 1

        External Route Tag: 0

Process ID 10

show ip route  ospf

---

From: "Nitin Kakkar" <[email-masked]>
Date: Mon, 27 Aug 2007 22:57:14 -0700

Jisnu,

   You have same prefix advertised in type 5 lsa, originated by two
distinct ASBR's 

    When ospf calculate route it will have to consider both lsa's which
means cost to ASBR's will come into play.   If ALL cost , type metric
matches both routes will be selected.  Otherwise best route will be
picked.

   Same rule applies with or without forwarding address (assuming fwd
address are different).

Hope this helps

Nitin

From: Jishnu Banerjee [mailto:[email-masked]] 
Sent: Monday, August 27, 2007 8:52 PM
To: Acee Lindem
Cc: [email-masked]
Subject: [OSPF] RE: Route Calculation for Type-5 LSA (default route)

Thanks Jishnu

Hi Jishnu,

Hi Acee,

Acee

-jishnu

Jishnu,

 

 

                                    \                       /

Now the questions are:

 

  LS age: 1355

  Network Mask: /0

  LS Seq Number: 80000083

        Metric Type: 1

        External Route Tag: 0

  Checksum: 0x8E49

        TOS: 0

  Length: 36

        Metric: 6

  LS age: 1217

  Network Mask: /0

  LS Seq Number: 80000085

        Metric Type: 1

        External Route Tag: 0

Process ID 10

show ip route ospf

---

From: Acee Lindem <[email-masked]>
Date: Tue, 28 Aug 2007 20:32:35 -0400

Hi Nitin,

Agree completely.

Thanks,
Acee
On Aug 28, 2007, at 1:57 AM, Nitin Kakkar wrote:

> distinct ASBR’s
>     When ospf calculate route it will have to consider both lsa’s  
> which means cost to ASBR’s will come into play.   If ALL cost ,  
> type metric matches both routes will be selected.  Otherwise best  
> route will be picked.
>
>
>
>    Same rule applies with or without forwarding address (assuming  
> fwd address are different).
>
> Hope this helps
>
> Nitin
>
> How about a situation like this è
>
> If same LSA (metric type E1 and metric being same) has been  
> advertised by two different ASBRs, each having non-zero fwding  
> address, then as per section 16.4, I find the following :
>
> Both ASBRs are reachable. Route to ASBR A1 is via nexthop on  
> interface IF1 while ASBR A2 is via nexthop on interface IF2. Both  
> route entries are of the same cost and both their associated area  
> being the same, subsequently the AS-paths to ASBR are of equal  
> preference being Inter-area paths.
> Considering the Fwd Address for the above ASBRs, if both of Fwd  
> Address (one on each ASBR) happens to be reachable in the same  
> pattern as above, then how do we break the tie ?
> On which interface should we expect the network (in this case  
> 0.0.0.0) should get resolved as OSPF E1 ?
>
>
>
> Thanks Jishnu
>
>
>
> RFC 2328 and it is clear that the route should be inherited from  
> the forwarding address route.
>
>
>
> Acee
>
>
>
>
>
>
>
> -jishnu
>
>
>
> 1.       2.Moreover I want to know whether Section 12.4.4 & Page  
> originated by the router having the highest OSPF Router ID is used.
>
>
>
>
>

---

From: "Jishnu Banerjee" <[email-masked]>
Date: Wed, 29 Aug 2007 11:09:30 +0530

Acee/Nitin,

"If ALL cost, type metric matches both routes will be installed" ==> Is
this what you advocate from the implementation perspective ? Because I
have not come across in the RFC (2328) or even Section G.7 (RFC 2178)
which mentions the same as you have advocated. Please correct me if my
understanding of the RFC is wrong in regards to the above situation.

As per your last email, external destination N will appear as ECMP,
although none of the Fwding Addresses are reachable via list of
nexthops.

Jishnu 

From: Acee Lindem [mailto:[email-masked]] 
Sent: Wednesday, August 29, 2007 6:03 AM
To: Nitin Kakkar
Cc: Jishnu Banerjee; [email-masked]
Subject: Re: [OSPF] RE: Route Calculation for Type-5 LSA (default route)

Hi Nitin,

Agree completely. 

Thanks,

Acee 

Jisnu,

Hope this helps

Nitin

From: Jishnu Banerjee [mailto:[email-masked]] 
Sent: Monday, August 27, 2007 8:52 PM
To: Acee Lindem
Cc: [email-masked] <mailto:[email-masked]> 
Subject: [OSPF] RE: Route Calculation for Type-5 LSA (default route)

Thanks Jishnu

From: Acee Lindem [mailto:[email-masked]] 
Sent: Monday, August 27, 2007 7:41 PM
To: Jishnu Banerjee
Cc: [email-masked] <mailto:[email-masked]> 
Subject: Re: Route Calculation for Type-5 LSA (default route)

Hi Jishnu,

Hi Acee,

Acee

-jishnu

From: Acee Lindem [mailto:[email-masked] <mailto:[email-masked]> ] 
Sent: Monday, August 27, 2007 7:05 PM
To: Jishnu Banerjee
Cc: [email-masked] <mailto:[email-masked]> ; Soman K. S
Subject: Re: Route Calculation for Type-5 LSA (default route)

Jishnu,

 

 

                                    \                       /The router
to be considered is R3. This R3 receives multiple External Type-1 LSAs
due to "default-originate" being used on remote routers which lie beyond
R1 & R2. Router R3 establishes adjacency with R1 and R2 on two different
broadcast segments.

  LS age: 1355

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

  LS Seq Number: 80000085

        External Route Tag: 0

show ip route ospf

---

From: "Nitin Kakkar" <[email-masked]>
Date: Tue, 28 Aug 2007 23:10:30 -0700

Jisnu,

   As far as I understand,  when forwarding address specified in a type
5 (or type 7)  LSA, is not reachable via Intra/Inter area route, you
will not use that LSA to calculate route. 

ECMP is discussed in sec 16.8 

16.8. Equal-cost multipath

The OSPF protocol maintains multiple equal-cost routes to all

destinations. This can be seen in the steps used above to

calculate the routing table, and in the definition of the

routing table structure.

Each one of the multiple routes will be of the same type

(intra-area, inter-area, type 1 external or type 2 external),

cost, and will have the same associated area. However, each

route may specify a separate next hop and Advertising router.

  I don't quite understand the part "none of the Fwding addresses are
reachable via list of nexthops"

Hope this helps

Nitin

From: Jishnu Banerjee [mailto:[email-masked]] 
Sent: Tuesday, August 28, 2007 10:40 PM
To: Acee Lindem; Nitin Kakkar
Cc: [email-masked]
Subject: RE: [OSPF] RE: Route Calculation for Type-5 LSA (default route)

Acee/Nitin,

Jishnu 

Hi Nitin,

Agree completely. 

Thanks,

Acee 

Jisnu,

Hope this helps

Nitin

Thanks Jishnu

Hi Jishnu,

Hi Acee,

Acee

-jishnu

Jishnu,

 

 

                                    \                       /The router

  LS age: 1355

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

  LS Seq Number: 80000085

        External Route Tag: 0

show ip route ospf

---

From: "Nitin Kakkar" <[email-masked]>
Date: Tue, 28 Aug 2007 23:41:45 -0700

Hello,

One correction to my previous mail,  I don't think RFC 2328 explicitly
talks about ECMP path across different area's. Acee can throw more
light.

Regards

Nitin

From: Nitin Kakkar 
Sent: Tuesday, August 28, 2007 11:11 PM
To: 'Jishnu Banerjee'; Acee Lindem
Cc: [email-masked]
Subject: RE: [OSPF] RE: Route Calculation for Type-5 LSA (default route)

Jisnu,

routing table structure.

 

Hope this helps

Nitin

Acee/Nitin,

Jishnu 

Hi Nitin,

Agree completely. 

Thanks,

Acee 

Jisnu,

Hope this helps

Nitin

Thanks Jishnu

Hi Jishnu,

Hi Acee,

Acee

-jishnu

Jishnu,

 

 

                                    \                       /The router

  LS age: 1355

  Network Mask: /0

        Metric Type: 1

        TOS: 0

        Metric: 6

  LS Seq Number: 80000085

        External Route Tag: 0

show ip route ospf