[nsp] Enquiry on MPLS across Public Network

[Harold Ritter]

John,

The issue with the additional overhead is that it can cause fragmentation. 
One way to prevent packet fragmentation is to use Path MTU Discovery with TCP.

At 05:37 PM 2/2/2004 -0800, John Pang wrote:
>Hi Harold,
>
>Thanks for the invaluable info. In this case, is there
>anyway to "overcome" potential problems caused by the
>24 + 4 = 28 bytes of overhead? Or will these 28bytes
>not cause too much of a problem?
>
>Best regards,
>
>--- Harold Ritter <hritter at cisco.com> wrote:
> > John,
> >
> > The same thing applies here, except that on top of
> > the 24 bytes of overhead
> > for GRE you have to factor in the MPLS overhead,
> > which is 4 bytes per label
> > in the stack.
> >
> > At 10:36 AM 1/29/2004 -0800, John Pang wrote:
> > >Hi Harold,
> > >
> > >Thanks for the suggestion. Do you happen to know
> > where
> > >I can find out more about how this can be done? Any
> > >docs to read up more about it?
> > >
> > >One thing I understand about GRE is that it takes
> > up
> > >24bytes of the MTU and hence may result in
> > >fragmentation problems.
> > >
> > >Will running MPLS over GRE be affected by this or
> > will
> > >it overcome this problem?
> > >
> > >Thanks,
> > >
> > >--- Harold Ritter <hritter at cisco.com> wrote:
> > > > John,
> > > >
> > > > At 09:05 PM 1/27/2004 -0800, John Pang wrote:
> > > > >Hi all,
> > > > >
> > > > >I am an ultra newbie on MPLS and currently
> > reading
> > > > up
> > > > >some Cisco docs on it.
> > > > >
> > > > >I amd wondering if it is possible to do an MPLS
> > VPN
> > > > or
> > > > >MPLS Traffic Engineering Tunnel across a Public
> > > > >Network (such as the Internet) to join one or
> > more
> > > > >remote sites together instead of other
> > technologies
> > > > >such as GRE?
> > > > >
> > > > > >From the docs which I read, it seems that for
> > any
> > > > form
> > > > >of MPLS to work, the provider (P) routers need
> > to
> > > > be
> > > > >configured to support MPLS but in the case of
> > the
> > > > >Internet being the public network, it may not
> > > > >necessarily have MPLS enabled on the various
> > ISPs
> > > > >routers.
> > > >
> > > > It is possible to run MPLS over a non-MPLS
> > enabled
> > > > network such as the
> > > > Internet but it requires using GRE to carry MPLS
> > > > frames.
> > > >
> > > >
> > > > >Have anyone tried this before and or can anyone
> > > > help
> > > > >shed light on this?
> > > > >
> > > > >Many thanks for your time and best regards,
> > > > >
> > > > >__________________________________
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> > > >
> > > > Harold Ritter, CCIE 4168 (R&S / SP)
> > > > Advanced Services - SP East
> > > > Cisco Systems
> > > > 1414 Massachusetts Avenue
> > > > Boxborough, MA 01719 USA
> > > > Phone: 978 936 1431
> > > > Cisco Systems- "Empowering the Internet
> > Generation."
> > > >
> > >
> > >
> > >__________________________________
> > >Do you Yahoo!?
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> >
> > Harold Ritter, CCIE 4168 (R&S / SP)
> > Advanced Services - SP East
> > Cisco Systems
> > 1414 Massachusetts Avenue
> > Boxborough, MA 01719 USA
> > Phone: 978 936 1431
> > Cisco Systems- "Empowering the Internet Generation."
> >
>
>
>__________________________________
>Do you Yahoo!?
>Yahoo! SiteBuilder - Free web site building tool. Try it!
>http://webhosting.yahoo.com/ps/sb/

Harold Ritter, CCIE 4168 (R&S / SP)
Advanced Services - SP East
Cisco Systems
1414 Massachusetts Avenue
Boxborough, MA 01719 USA
Phone: 978 936 1431
Cisco Systems- "Empowering the Internet Generation."