From: Lee Donald (Lee.Donald@t-systems.co.uk)
Date: Thu Sep 08 2005 - 11:50:31 GMT-3
Duongla,
That is not correct. The router will add it's own cost on before installing
in the routing table. It will then advertise the route to R3 with the same
cost as it has.
To prove it here is my setup.
R1 has a rip route 222.22.2.0/24 as shown.........
R 222.22.2.0/24 [120/7] via 192.10.1.254, 00:00:15, FastEthernet0/0
R2 learns this route from R1 and this is the route in R2's table......
R 222.22.2.0/24 [120/8] via 12.12.13.1, 00:00:18, Serial0/0
R2 has added an additional hop ( it's own cost) and installed it in it's
routing table.
My Topology is as follows............ R1---ser0/0-----ser0/0----R2
I HTH
Lee.
-----Original Message-----
From: Duongla [mailto:duongla@vnn.vn]
Sent: 08 September 2005 15:35
To: Lee Donald; Cisco certification
Subject: Re: IPv6 RIP metric: strange calculation
Lee,
As far as I know, the normal behaviour of RIP (both ipv4 and ipv6) is: when
a router receives a route with metric of N then it installs the route in the
routing table with metric of N ( no increase). Then the router will
advertise the route out its interfaces with metric of (N+1).
Do you agree ?
Here, the problem is at R2: it increases the metric by one before it
installs the route int routing table. That's why R2 sees Z 2 hops away. In
fact, it is just 1 hop. And from R3 and on if we have a chain of routers,
the metric of route to Z will be 1 hop count greater than its actual metric.
Thanks
Duongla
----- Original Message -----
From: "Lee Donald" <Lee.Donald@t-systems.co.uk>
To: "Duongla" <duongla@vnn.vn>; "Lee Donald" <Lee.Donald@t-systems.co.uk>;
"Cisco certification" <ccielab@groupstudy.com>
Sent: Thursday, September 08, 2005 9:33 PM
Subject: RE: IPv6 RIP metric: strange calculation
> Duongla,
>
> You've said below that R2 receives the route with a metric of 1, then R2
> would add it's own cost onto the route, so R2 now has a cost of 2 for this
> route. R2 would send this route to R3 with a cost of 2, R3 would add it's
> own cost on and then R3 would have this route with a cost of 3.
>
> That is correct as far as I can read it??
>
> Regards
>
> Lee.
>
>
> :)
>
>
>
>
>
> -----Original Message-----
> From: Duongla [mailto:duongla@vnn.vn]
> Sent: 08 September 2005 15:22
> To: Lee Donald; Cisco certification
> Subject: Re: IPv6 RIP metric: strange calculation
>
> Hi Lee
>
> From R3, the metric to destination Z should be 2 hop-counts (R2-R1). The
> problem starts at R2, he he.
> Pls review the scenario if you could help.
>
> Thanks
> Duongla
> ----- Original Message -----
> From: "Lee Donald" <Lee.Donald@t-systems.co.uk>
> To: "Duongla" <duongla@vnn.vn>; "Cisco certification"
> <ccielab@groupstudy.com>
> Sent: Thursday, September 08, 2005 9:15 PM
> Subject: RE: IPv6 RIP metric: strange calculation
>
>
> > What problem?
> >
> > R3 should have a metric of 3 should it not?
> >
> > On your topology R2 has the route with a metric of 2, passes it to R3,
now
> > R3 has the route with a metric of 3, hop count has increased by 1 hop,
> which
> > is correct.
> >
> > Regards
> >
> > Lee.
> >
> >
> >
> > -----Original Message-----
> > From: Duongla [mailto:duongla@vnn.vn]
> > Sent: 08 September 2005 14:54
> > To: Cisco certification
> > Subject: IPv6 RIP metric: strange calculation
> >
> > Hi group,
> >
> > Doing a simple IPv6 RIP lab on 3 routers:
> > f0/0-R1-s0/0------s0/0-R2-s0/1------s0/0-R3-f0/0
> > Suppose R1 f0/0 IPv6 address is Z.
> > I noticed the following:
> > R1 advertises Z with metric of 1: this is normal behaviour
> > R2 receives the route Z with metric of 1. "show ipv6 route" output
shows
> > route Z with metric 2. R2 continues to send route Z metric 2 to R3
without
> > increasing the metric.
> > R3 has a route to Z with metric 3. It also sends the route out int
f0/0
> > with
> > metric 3.
> > All my routers use c2600-is-mz.122-15.T16.bin. Is this the bug of the
IOS
> ?
> >
> > Has anyone got the same problem ?
> >
> > Regards
> > Duongla
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sun Oct 02 2005 - 14:40:14 GMT-3