From: Mas Kato (tealp729@xxxxxxxx)
Date: Mon May 28 2001 - 02:16:19 GMT-3
Bud,
Thanks for clearing it up, because...
You originally stated "A virtual link provides a transparent connection
through another area (which must itself be connected to area 0) to area
0. This kind of 'virtual connection' concept is known as tunnelling;
same as DLSW, IPX, IP over IP, VOIP tunnels."
Excuse me, but since you stated this in reference to Curtis' response,
it sounded to me like you were implying that the routed traffic was
being tunnelled like "DLSW, IPX, IP over IP, VOIP" to the backbone
first, before it went into other areas. All I'm saying is, this is not
the case.
<You say "The virtual-link provides a kind of "point-to-point
demand-circuit" ; how vague can you be?>
The "point-to-point" part comes right out of the RFC and the
"demand-circuit" part would be evident if you were to examine the OSPF
database when virtual-links are operating.
Cheers,
Mas
-----Original Message-----
From: eugeneonline [mailto:eugeneonline@yahoo.com]
Sent: Sunday, May 27, 2001 7:32 PM
To: Mas Kato; 'Curtis Call'; 'ANDY NWEBUBE'
Cc: ccielab@groupstudy.com
Subject: RE: Virtual Links
Mate,
Sorry that CCIE candidates do not seem to understand the basics of
software tunelling. TUNNELING PROVIDES ALTERNATIVE TO THE NATIVE
CONNECTIVITY PROCEDURE. In this case there is no physical/datalink
conectivity, so connectivity is achieved through software interface.
You say "routED traffic follows the best route provided by the routing
protocol" There is no disagreement as to routing decision here: as I
said SPF WILL DECIDE (concurs with Curtis in his words"the traffic still
goes hop by hop throughout the OSPF domain". ) . Your point therefore is
irrelevant/duplicate.
Curtis writes: " Virtual Links are not tunnels, you can't transport
traffic over them, they just carry routing information" Well guess what
:They are TUNNELING this routing information through area 1. THIS IS THE
PRINCIPLE OF TUNNELLING. IT IS NOT ONLY APPLICATION DATA THAT IS
TUNNELED : IN THIS CASE ROUTING UPDATES ARE BEING TUNNELED!
You say "The virtual-link provides a kind of "point-to-point
demand-circuit" ; how vague can you be?
Chaps, you seem to know only Cisco exam material (tunnel interfaces)
please read further afield and grasp generics/basics of software
programming principles, you are going to be CCIEs (hopefully). We don't
want to be paper/exam CCIEs like MCSE/CNE now do we?
Regards,
Eugene
Mas Kato <tealp729@home.com> wrote:
Sorry Eugene, but Curtis is correct. The virtual-link provides a kind of
"point-to-point demand-circuit" across area 1 for the routING protocol
traffic, but the routED traffic follows the best route provided by the
routing protocol.
Mas
Go Lakers!
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
eugeneonline
Sent: Sunday, May 27, 2001 10:39 AM
To: Curtis Call; ANDY NWEBUBE
Cc: ccielab@groupstudy.com
Subject: Re: Virtual Links
Hi Curtis,
RFC states that all OSPF areas must be connected to area 0. A virtual
link provides a transparent connection through another area (which must
itself be connected to area 0) to area 0. This kind of 'virtual
connection' concept is known as tunnelling; same as DLSW, IPX, IP over
IP, VOIP tunnels.
Regards,
Eugene
Curtis Call wrote: Traffic from R2 to R1 will go
directly from R2 to R1. Remember that in
order to have R2 be a virtual link it will have an interface in Area 1,
therefore to reach any destination in Area 1 it will always use the
intra-area route. Besides, Virtual Links are not tunnels, you can't
transport traffic over them, they just carry routing information, the
traffic still goes hop by hop throughout the OSPF domain.
At 12:54 AM 5/25/01, you wrote:
>Guys,
>
>I wonder if their is anybody who remembers the discussion on Virtual
>Links in OSPF. It was posted some time ago but I can't seem to find it.
>
>The scenario was something like this:
>________ _______ _______
>|Area 0| |Area1| |Area2|
>| R0 |--| R1 |--| R2 |
>|______| |_____| |_____|
>
>There is a virtual link from area 2 to Area 0 via Area1. Traffic needs
to
>get to R1 in Area 1 from R2 in Area 2. Assume that the virtual link has
to
>use R1 (To create the V.Link! ). Does the traffic flow passed R1 (in
Area
1)
>to Area 0 and then back to area 1, or does the actuall flow just to R1
from R2.
>
>I cant remember the conclusion, and I cant seem to find it on the
>archives. Quite interesting issues.
>
>Regards,
>Andy
>
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