Re: OSPF Route type when ospf as PE-CE routing protocol

Hi Bob,

Thanks for your reply on this.

I think your explanation on this holds good. Just i had this doubt as most
of the books say that value can be 1 or 2 depending on LSA type 1 or 2 but i
haven't seen this value as 1 in any scenario so just wanted to confirm if
there was any way we can have this as 1 if LSA type is 1. I also think as
you explained Cisco implementation is to make route type as 2 for all
internal routes.

Also other doubt i have is that in OSPF router ID field RFC says that after
4 byte router ID, 2 byte un-used field should be always 0, but i see this
value as 512 on all the cisco routers. Any clue what this 512 value indicate
and why it is used as 512 instead of 0.

Thanks & Regards,
Gaurav Thukral

 OSPF ROUTER ID:44.44.44.2:512,

On Tue, May 18, 2010 at 7:19 AM, Bob Sinclair <bob_at_bobsinclair.net> wrote:

> Hello Gaurav,
>
> All of the documentation I can find, including a search of most of the
> clueful books on Safari, the RFCs and a general Google search indicate that
> we "should" see route type 1 for LSA type 1 and route type 2 for LSA type
> 2.
>
>
> I always see route type 2 as the extended community value for the OSPF
> internal routes in another site. This does NOT however point to a Type 2,
> Network LSA; even p-p loopback interfaces are reported as route type 2.
>
> I think Cisco simply uses the 2 to indicate an OSPF internal route, not
> really an LSA type.
>
> Maybe someone else on the list has more clue.
>
> Best regards,
>
> Bob Sinclair
>
> > -----Original Message-----
> > From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> > Gaurav Thukral
> > Sent: Monday, May 17, 2010 2:33 PM
> > To: Group study
> > Subject: OSPF Route type when ospf as PE-CE routing protocol
> >
> > Hi Experts,
> >
> > I have one doubt regarding Cisco's implementation of OSPF as PE-CE
> > routing
> > protocol :-
> >
> > On ingress PE's PE-CE protocol I have LSA type 1 route :-
> >
> > 106#sh ip ospf 101 database
> >
> > OSPF Router with ID (44.44.44.2) (Process ID 101)
> >
> > *Router Link States (Area 0)*
> >
> > Link ID ADV Router Age Seq# Checksum Link
> > count
> > *44.44.44.2 44.44.44.2 1759 0x8000000A 0x00AB8F 2*
> > 108.108.108.108 108.108.108.108 1760 0x8000000A 0x00B957 2
> >
> > Summary Net Link States (Area 0)
> >
> > Link ID ADV Router Age Seq# Checksum
> > 11.11.11.0 44.44.44.2 1381 0x80000001 0x004EC5
> > 77.77.77.0 44.44.44.2 1381 0x80000001 0x00FC50
> > 100.100.100.100 44.44.44.2 1381 0x80000001 0x003663
> > 108.108.108.108 108.108.108.108 832 0x80000005 0x005B79
> > 111.111.111.111 44.44.44.2 1381 0x80000001 0x003A33
> >
> > Type-5 AS External Link States
> >
> > Link ID ADV Router Age Seq# Checksum Tag
> > 1.1.1.1 108.108.108.108 832 0x80000005 0x0079ED 0
> > 2.2.2.2 108.108.108.108 832 0x80000005 0x00CE14 0
> > 106#
> >
> > Now when this route is redistributed into MP-BGP on local PE, this
> > route
> > shows as LSA type2 :-
> >
> > 106#sh ip bgp vpnv4 vrf cust_a *44.44.44.0*
> > BGP routing table entry for 1:100:44.44.44.0/24, version 40
> > Paths: (1 available, best #1, table cust_a)
> > Advertised to update-groups:
> > 1
> > Local
> > 0.0.0.0 from 0.0.0.0 (106.106.106.106)
> > Origin incomplete, metric 0, localpref 100, weight 32768, valid,
> > sourced, best
> > Extended Community: RT:1:100 OSPF DOMAIN
> > ID:0x0005:0x000000650200
> > *OSPF RT:0.0.0.0:2:0* OSPF ROUTER ID:44.44.44.2:512,
> >
> > mpls labels in/out 26/nolabel
> >
> >
> > According to my understanding and also have gone through PE-CE RFC, it
> > should have been LSA type 1 only.
> > Anyone can help me understand this behavior.
> >
> > Thanks in advance.
> >
> >
> > --
> > Regards,
> >
> > *Gaurav Thukral*
> >
> >
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> >
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> >
> >
> >
> >
> >
> >
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>
>

-- 
Regards,
*Gaurav Thukral* , CCIE#21156( R&S)
CCIE SP (Q), CCIP, CCDP, CCNA , SCSA
Senior Technical Instructor - Labsnracks
Mailto: gthukral_at_labsnracks.com
Mob: +91 9988306306
Web: http://www.labsnracks.com
Visit my Blog : http://www.myippackets.com
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