The MPLS-OPS Archive

[Roger Clark Williams <rogerw@nordlink.com>]

It may be totally obvious to all, but since no one has said it
specifically I thought I would at least state it.

You want to preserve the RIP hop count specifically when working with a
VPN. Since RIP has a maximum of 15 usable hops, the journey from one end
of a customer network (including a VPN) to the other could come close to
using up the hops available. The MPLS core wants to look like a single
hop to the customer, and passing the hop count to the BGP MED and back
again accomplishes that.

Roger Williams

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Date: Thu, 22 May 2003 13:33:18 -0700 (PDT)
From: Yinglam Cheung <ccie6961@yahoo.com>
Reply-To: ccie6961@yahoo.com
Subject: Re: [MPLS-OPS]: Reg: redistrbiute - transparent
To: Kishoren <kishoren@huawei.com>, mpls-ops@mplsrc.com
Cc: "Doukov, Roumen" <RDoukov@flagtelecom.com>
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It's useless if you have multiple ISP/AS in between, but it'll be very useful to preserve the RIP hop count between a single BGP AS, in this case, like a MPLS backbone using single AS.
A caveat I have found in low end Cisco routers is that, for some reason, it changes the hop count to 16 (which is indefinite) if I uses transparent. In high end router, I don't see this problem.

Kishoren <kishoren@huawei.com> wrote:

Hi Roumen,

 

    Thank you for your reply.

 

    You are saying that RIP hopcount is preserved and transported on BGP.

Can you please tell me what is the use of doing this. MED may not be sent transparently

if there are many routers of ISP involved while routing. And RIP hopcount itself

will not be of much use as there are other PE routers (transparent)

whose hopcount is not accounted.

 

Regards

Nanda kishore

 

P.s: Pls find a link in CISCO where they used this command

http://www.cisco.com/en/US/products/hw/routers/ps314/products_feature_guide_chapter09186a008007e267.html

 

----------------------------------------------

Nanda Kishore

Huawei Technologies

Phone:  5217152 ext: 670

            5354259 (R)

Huawei 3rd Floor,

Leela Galleria, Airport Road,

Bangalore - India

----------------------------------------------

----- Original Message -----

From: Doukov, Roumen

To: 'Kishoren'

Sent: Monday, May 19, 2003 3:47 PM

Subject: RE: [MPLS-OPS]: Reg: redistrbiute - transparent

You preserve the RIP hop count, so the CE-PE RIP hop-count is copied into BGP MED and BGP MED copied back to RIP hop count when route is put back into RIP.

Roumen

-----Original Message-----

From: Kishoren [mailto:kishoren@huawei.com]

Sent: 19 May 2003 10:35

To: mpls-ops@mplsrc.com

Subject: [MPLS-OPS]: Reg: redistrbiute - transparent

Hi,

 

    Can any one explain what does "redistribute bgp transparent"

will do, if I am redistributing BGP routes into RIP. I couldn't get

any information on that.

 

A link explaining this will be great.

 

Regards

Nanda kishore

 

 

----------------------------------------------

Nanda Kishore

Huawei Technologies

Phone:  5217152 ext: 670

            5354259 (R)

Huawei 3rd Floor,

Leela Galleria, Airport Road,

Bangalore - India

----------------------------------------------

best regards,
Yinglam Cheung
CCIE #6961 (R&S, C&S, Security)


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