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Routing protocol for MPLS

 
 
bluetooth995@gmail.com
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      10-23-2005
Hi

A bit confuse with MPLS, Please help on this:

1) is ATM or FR use in MPLS?
2) what' s the routing protocol used? I know it used label switching by
adding label on the header to aids in the routing of packets.
3) which layer does MPLS falls in OSI model , L2 or L3 ?
4) is MPLS considered a true leased line (Private line)?

Thanks

 
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www.networking-forum.com
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      10-23-2005
With my limited understanding, here are my answers:

1) No, it replaces ATM and FR.
2) Any interior routing protocol can be used. IS-IS, EIGRP, OSPF, RIP, etc.
3) I'd say it's layer 2.
4) Yes. I think you are referring to the popular product MPLS VPN. In
which case, MPLS traffic can be designated as belonging to a specific
customer.

Regards,
Steve
www.networking-forum.com


<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...
> Hi
>
> A bit confuse with MPLS, Please help on this:
>
> 1) is ATM or FR use in MPLS?
> 2) what' s the routing protocol used? I know it used label switching by
> adding label on the header to aids in the routing of packets.
> 3) which layer does MPLS falls in OSI model , L2 or L3 ?
> 4) is MPLS considered a true leased line (Private line)?
>
> Thanks
>



 
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stephen
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      10-23-2005
<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...
> Hi
>
> A bit confuse with MPLS, Please help on this:
>
> 1) is ATM or FR use in MPLS?


there are 2 basic flavours of MPLS. 1 is cell based and often uses the same
hardware as ATM. The much more common flavour is packet based and is more
about labels used as a "shim" layer between IP and the underlying layer 2.

labels are only used in the core network.

ATM / FR can be used as a transport - MPLS doesnt care what is under the IP
layer at the edge.

my employer uses Frame relay encapsulation over E1 and n* 64k links to allow
multiple VPNs to CE router.

> 2) what' s the routing protocol used? I know it used label switching by
> adding label on the header to aids in the routing of packets.


theres a bunch of different bits that uses routing protocols

you need an IP routing protocol in the core (often IS-IS), a label
distribution protocol, and protocols to distribute routes for different
VPNs, often MP-BGP.

then you need routing from the edge (CE) routers into the label switching
domain (PE routers) - we allow a mix here, including statics, BGP, EIGRP and
RIP - the choice depends on the customer, the resilience requirements,and
whether dynamic routes are needed in other bits - e.g. for links to other
carriers.

> 3) which layer does MPLS falls in OSI model , L2 or L3 ?


you could argue both or neither. MPLS can carry IP, ATM, Frame, Ethernet
traffic - which makes it layer 2 or lower - but it also has route style
management, which makes it layer 3.

In reality it is sort of sideways on to the "customer" protocol stack, since
it is there to allow multiple networks to share a common backbone. Similar
arguments apply to an ATM switch core - the protocol standards are about the
interfaces to devices at the cloud edge, not how the cloud operates
internally.

> 4) is MPLS considered a true leased line (Private line)?


No - but it can use a leased line.

Given some of the assumptions in these Qs - you need to go and find a good
background on MPLS

an intro
http://www.cisco.com/application/pdf...cd8031205f.pdf

a bunch of cisco info
www.cisco.com/go/mpls

try RFC2547 for MPLS VPNs from a vendor neutral perspective.

>
> Thanks
>

--
Regards

http://www.velocityreviews.com/forums/(E-Mail Removed) - replace xyz with ntl


 
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nospam
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      10-24-2005
Thanks

 
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