From: Daniel Free (danrose111@earthlink.net)
Date: Fri Apr 25 2003 - 17:49:47 GMT-3
Please don't kill me. I made a typo in the last email
Network should be:
R1, R2 and R3 are DRothers and R4 is BDR and
R5 is DR. Take Care!!!!
----- Original Message -----
From: "Daniel Free" <danrose111@earthlink.net>
To: "Daniel Free" <danrose111@earthlink.net>; "ccie2be"
<ccie2be@nyc.rr.com>; "Jon CarMicheal" <jonc@whirled-routers.com>; "Group
Study" <ccielab@groupstudy.com>
Cc: <ted.Okuzumi@barclayscapital.com>
Sent: Friday, April 25, 2003 4:31 PM
Subject: Re: OSPF virtual link in combo with ethernet
> Hi Jim,
> I just finished doing your scenario on my lab.
> You are 100 % correct. Very sorry for my initial
> response to this question. This will teach me to be
> sure before I answer. I made R1,R2,R3,R4,R5
> ethernets in area 1. I added Area 0 to R1 and R2.
> I added Area 3 to R3, Area 4 to R4 and Area 5 to
> R5. R1 was the DR, R2 was DRother, R3 was DRother, R4 was DRother. R5 was
> BDR. I had absolutely no problem establishing virtuals links
> from R3,R4 and R5 to R2. For fun I established R3
> and R4 virtual links to R2 and R5 virtual link to R1.
> So you are correct in the fact that in this scenario
> it will work because virtual-links are using router id's. If this was a
> production environment you would
> also want to establish dual virtual-links. One from
> R3,R4 and R5 to R1 and one from R3,R4 and R5
> to R2 for redundancy purposes. It's been fun. Best of luck.
> Danny
> ----- Original Message -----
> From: "Daniel Free" <danrose111@earthlink.net>
> To: "ccie2be" <ccie2be@nyc.rr.com>; "Jon CarMicheal"
> <jonc@whirled-routers.com>; "Group Study" <ccielab@groupstudy.com>
> Sent: Friday, April 25, 2003 4:20 AM
> Subject: Re: OSPF virtual link in combo with ethernet
>
>
> > Hi Jim,
> > I will have to lab this and get back to you.
> > Danny
> > ----- Original Message -----
> > From: "ccie2be" <ccie2be@nyc.rr.com>
> > To: "Jon CarMicheal" <jonc@whirled-routers.com>; "Group Study"
> > <ccielab@groupstudy.com>; "Daniel Free" <danrose111@earthlink.net>
> > Sent: Thursday, April 24, 2003 7:49 PM
> > Subject: Re: OSPF virtual link in combo with ethernet
> >
> >
> > > Hey Danny and Jon,
> > >
> > > Thanks for getting back to me. I appreciate it.
> > >
> > > Although I accept what you're saying as true, it doesn't really make
> sense
> > > to me. Here's why.
> > >
> > > 1st of all, a virtual link is configured between router ID's so as to
> > create
> > > a tunnel between ABR's. And, nothing I've come across says that the
> ABR's
> > > have to be adjacent.
> > >
> > > 2nd, if the ABR's had to be adjacent, then it wouldn't be possible to
> have
> > a
> > > virtual link between 2 ABR's that weren't directly connected as in
> > >
> > > non-backbone area --- R1--- transit area --- R2 --- transit area ---
> > R3 ---
> > > area0
> > >
> > > If ABR's had to be adjacent you couldn't have a virtual link between
R1
> > and
> > > R3.
> > >
> > > Now consider this topology:
> > >
> > >
> > > Area 0
> > > | |
> > > R1 R2
> > > |-----|---------|--------| Ethernet segment with all interfaces in
> > Area1
> > > | | |
> > > R3 R4 R5 where R4= BDR and R5=DR
> > > | | |
> > > A3 A4 A5 where A = area
> > >
> > >
> > > In this topology, is it possible that a virtual link can't be created
> > > between R3 and either R1 or R2? does that make sense?
> > >
> > > If you (or somebody else on Group STudy) could explain this to me, I'd
> be
> > > one happy camper. Thanks. Jim
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Daniel Free" <danrose111@earthlink.net>
> > > To: "ccie2be" <ccie2be@nyc.rr.com>; "Group Study"
> <ccielab@groupstudy.com>
> > > Sent: Thursday, April 24, 2003 5:40 PM
> > > Subject: Re: OSPF virtual link in combo with ethernet
> > >
> > >
> > > > Hi Jim,
> > > > Your very last statement is correct. Just think of how OSPF works on
a
> > > > broadcast medium. There
> > > > will be a DR/BDR election process. Each non DR/BDR router (DRother)
> > forms
> > > an
> > > > adjacency with
> > > > a DR and a BDR. In your sample you need to configure the virtual
link
> to
> > > > Router A, in this case the BDR because it is attached to Area 0.
Best
> of
> > > > luck.
> > > > Danny
> > > > ----- Original Message -----
> > > > From: "ccie2be" <ccie2be@nyc.rr.com>
> > > > To: "Group Study" <ccielab@groupstudy.com>
> > > > Sent: Thursday, April 24, 2003 3:47 PM
> > > > Subject: OSPF virtual link in combo with ethernet
> > > >
> > > >
> > > > > Hi group,
> > > > >
> > > > > I have 4 routers, A, B, C and D on an ethernet segment with each
> > > router's
> > > > > ethernet interface configured to be in OSPF area 1. Routers A and
B
> > are
> > > > ABRs
> > > > > between area 0 and area 1. Router C is also an ABR between area 1
> and
> > > > area
> > > > > 2.
> > > > >
> > > > > When I configured a virtual link between rtr C and B it doesn't
> work -
> > > the
> > > > > output of show ip ospf virtual-link shows the v-link down.
However,
> > > when
> > > > I
> > > > > configure the v-link between rtr C and A, it does work. I'm
trying
> to
> > > > figure
> > > > > out why this is.
> > > > >
> > > > > On rtr C, I did a show ip ospf nei and saw the following:
> > > > >
> > > > > nei A Full/BDR
> > > > > nei B 2way/DRother
> > > > > nei D Full/DR
> > > > >
> > > > >
> > > > > Also, when I ping trace between rtr C and B, it takes 2 hops, not
1
> > even
> > > > > though both rtr C and B are on the same ethernet segment.
> > > > >
> > > > > Given the above info, is it possible that a virtual link across an
> > > > ethernet
> > > > > segment has to be between a router and the DR or BDR on the
segment?
> > > > >
> > > > > Thanks in advanced. Jim
This archive was generated by hypermail 2.1.4 : Thu May 01 2003 - 13:36:07 GMT-3