[c-nsp] [j-nsp] lsp ping between JNPR and Cisco

Marlon Duksa mduksa at gmail.com
Mon Dec 8 17:20:08 EST 2008

When we replaced Csco with JNPR box as transit LSR, the PING worked. With or
Obviously there is an interop issue between Csco and JNPR, namely Cisco is
decrementing IP TTL as penultimate hop. And we don't know how to disable

On Sat, Dec 6, 2008 at 12:20 PM, <Daniel.Hilj at synetrix.co.uk> wrote:

> I take it that you already configured on the loopbacks which is
> required for MPLS ping to work on Junipers?
> Regards
> Daniel
> -----Original Message-----
> From: Marlon Duksa <mduksa at gmail.com>
> Sent: 05 December 2008 22:57
> To: Juniper-Nsp <juniper-nsp at puck.nether.net>; cisco-nsp at puck.nether.net <
> cisco-nsp at puck.nether.net>
> Subject: [j-nsp] lsp ping between JNPR and Cisco
> Our RSVP tunnel endpoints are JNPR boxes (M320) and a transit node is Cisco
> (7600). When we try to initiate MPLS ping from JNPR to JNPR through Cisco,
> the mpls ping fails.
> The reason is that JNPR is always setting IP TTL as 1. Since the Cisco is a
> penultimate node, it strips the label, decrement the IP TTL (to 0) and send
> the packet to JNPR. JNPR discards it since the IP TTL is 0.
> Does anyone know if there is any workaround to this?
> It looks to me that the only option is to try to set the IP TTL in MPLS
> ping
> from ingress JNPR to something > 0. Unfortunately there is no provision
> that
> would allow us to do this.
> On the other hand, Cisco won't honor 'no-ttl-decrement' statement on the
> penultimate if MPLS TTL is greater then the IP TTL (which currently is
> since
> JNPR MPLS TTL is set to 255).
> Thanks,
> Marlon

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