Enabling MPLS on non Cisco Routers

Unanswered Question
Dec 13th, 2008

Hi all,

Am studying for the ISCW exam and am confused on MPLS. Can MPLS be run on non Cisco routers?

Reason why I ask is because CEF must be enabled on the router before you can run MPLS, however CEF is Cisco propriatary. Then this leads me onto my next question. If you do have Cisco routers across your MPLS network, then why not run the TDP label protocol (or shall I say tag protocol)? Why go for the LDP industry standard when you are on Cisco routers anyway?

I know this is an obvious answer and doubt this particular question will show up on my exam (I hope!) but could someone please put my curiousity to rest.

Thanks in advance

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Giuseppe Larosa Sat, 12/13/2008 - 12:16

Hello Sachin,

MPLS can be used on a vast range of other vendors equipment.

see the IP/MPLS forum

http://www.ipmplsforum.org/

Each vendor has its own forwarding optimization technologies, so even if they haven't CEF they will use what is available to them as a basis to build LFIB tables.

There are big providers that have chosen to have multivendor neworks and use for each role the best device they find with comparative tests. (other factors are important too)

There are some very important features that are available only with LDP: for example the capability to use LDP as signalling protocol for EoMPLS as an example.

Cisco has decided to stop to develop new features in TDP.

So TDP is the past LDP the current label distribution protocol.

The first network I worked with MPLS in 2000/2001 was using TDP and no LDP was available.

For another network in 2001-2002 we already suggested the usage of LDP and it was implemented with LDP.

Besides this using LDP makes the network multivendor ready.

Another case is that of 802.1Q versus ISL: ISL is not supported in some new low end switches (relatively new as 2950)there are reasons to prefer ISL over 802.1Q ?

Hope to help

Giuseppe

jayjorda Sat, 12/13/2008 - 14:55

CEF is required on Cisco routers to support MPLS because that is the forwarding mechanism IOS uses to create the LFIB. Other vendors will have their own forwarding mechanism and they may have their own requirements that must be configured in order for MPLS to operate.

TDP was Cisco's original Labael Distribution Protocol, but LDP has become the standard and all development of new features and enhancements is being done on LDP, not TDP. TDP does not support any of the advanced LDP features since development on it has been stopped for a number of years now.

Using LDP allows multivendor interoperability even if your network is all Cisco when you deploy MPLS. Using LDP from the start allows you to avoid any TDP to LDP migration you may have to go through if you introduce another vendor.

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