The MPLS-OPS Archive

[Robert Raszuk <raszuk@cisco.com>]

I failed to see any reference to traffic eng in this entire thread.

R.

> Vic Nowoslawski wrote:
> 
> MTU is advertized by RSVP-TE, in the SENDER_TSPEC object of the path message.
> 
> At 05:38 PM 2/22/2002 +0100, Robert Raszuk wrote:
> 
> >Krzysiek,
> >
> >No. The MTU in the output of "show mpls forwarding-table X.X.X.X.
> >detail" has nothing to do with MTU :). The term "MTU" there is a
> >misnomer, it should be actually a maximum receive unit.
> >
> >If the "MTU=" there is xyz then it implies that a labeled packet of size
> >xyz bytes can be *received* by the router and sent out on interface
> >indiacted without needing to fragment it. the MTU printed out depends on
> >each prefix and could have different values depending on how many labels
> >are pushed/popped.
> >
> >It also has nothing to do with LDP. LDP at least for now does not
> >advertise MTU :). I am assuming you are talking about extensions
> >proposed in: draft-black-ldp-mtu-extensions-00.txt right ?
> >
> >R.
> >
> >
> > > Krzysztof Szarkowicz wrote:
> > >
> > > Check what MTU size is advertised by your LDP protocol (show mpls
> > forwarding-table X.X.X.X. detail)
> > >
> > > Regards,
> > > Krzysztof Szarkowicz
> > >
> > > ----- Original Message -----
> > > From: "Donn Lasher" <dlasher@clearskynet.net>
> > > To: <mpls-ops@mplsrc.com>
> > > Sent: Thursday, February 21, 2002 8:26 PM
> > > Subject: MPLS & Path MTU problems
> > >
> > > >
> > > > I've read all the MPLS-OPS archives on this issue, and tried the
> > fixes, and
> > > > I'm still seeing a problem.
> > > >
> > > > two 3620's running 12.2.6, hooked to a 3524 switch. Multiple MPLS/Dot1Q
> > > > vlan's off both routers. When traffic passing through these routers
> > from a
> > > > customer to a site blocking PMTU discovery(nice long list any more),
> > it all
> > > > the traffice appears to the customer to be blackholed.
> > > >
> > > > ip icmp debug shows:
> > > >
> > > > Feb 20 22:39:11 X.X.X.X 5813: 3w5d: ICMP: dst (X.X.X.X) frag. needed
> > and DF
> > > > set unreachable sent to 216.221.138.92
> > > > Feb 20 22:39:12 X.X.X.X 5815: 3w5d: ICMP: dst (X.X.X.X) frag. needed
> > and DF
> > > > set unreachable sent to 216.221.138.92
> > > >
> > > > At the moment I'm applying a route-map to clear df bit on my NSP
> > connected
> > > > router, but that's a hack. I'd really like to find and solve the real
> > issue.
> > > >
> > > > Ethernet MTU is 1500. tag-switching MTU unset (defaulting to 1500)
> > > > tag-switching ip set on all interfaces
> > > >
> > > > I've tried setting the tag-switching mtu to 1540, making sure the switch
> > > > was set mtu 2018, didn't make any difference.
> > > >
> > > > Thanks in advance for any help.
> > > >
> > > >
> > > >
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> > > >
> > >
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> 
> Vic Nowoslawski
> Tel. 703-794-8398
> Cell. 703-338-7701
> e-mail. vnowoslawski@mac.com

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