The MPLS-OPS Archive

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

Mourad, these are the IOS commands you may need:

tag-switching ip propagate-ttl

or

mpls ip propagate-ttl

It is my understanding the translation works like this:

Normally, the IP TTL is copied (with 1 step decrement) into the MPLS TTL.
Across the MPLS network the MPLS TTL will be decremented at each hop, and
it will overwrite the IP TTL at the egress.

If you use either of these commands, the IP TTL is not copied into the
MPLS TTL field. Instead, the MPLS TTL will be written as 255, and
decremented across the MPLS network. In cell mode, (no TTL in ATM cells)
the total number of hops will be decremented at the beginning of the
ingress, and only if there is at least a positive 1 hop will the cell be
sent across the ATM portion of the network.

I hope this helps

Roger Williams




> Resent-Date: Fri, 28 Mar 2003
> 05:23:25 -0500
> X-Authentication-Warning: host.secure4-hosting.net: mplsrc12 set sender
> to mpls-ops-request@mplsrc.com using -f
> From: Mourad BERKANE <mourad.berkane@lambdanet.fr>
> To: "'R V'" <rvb17@hotmail.com>
> Cc: mpls-ops@mplsrc.com
> Subject: RE: [MPLS-OPS]: MPLS ping vs normal Ping
> Date: Fri, 28 Mar 2003 11:06:45 +0100
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>
> IP TTL is generally map to MPLS TTL but you could hopefully
> disable it and avoid ICMP message each time you cross a LSR. 
>
> For more infos, please refer to following draft (ICMP
> Extensions for MultiProtocol Label Switching) 
>
> draft-bonica-icmp-mpls-0x.txt 
>
> Regards, 
> Mourad 
>
> -----Message d'origine----- 
> De : R V
> [mailto:rvb17@hotmail.com]
> Envoyé : jeudi 27 mars 2003 18:38 
> À : mpls-ops@mplsrc.com 
> Objet : [MPLS-OPS]: MPLS ping vs normal Ping 
>
> does anybody know how ping implementation for MPLS doman is
> different from 
> ping in IP domain? 
>
> Regards 
> RV 
>
>
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