# Introduction to MPLS

**URL:** https://forum.networklessons.com/t/introduction-to-mpls/1282
**Category:** Lessons Discussion
**Created:** [December 29, 2016, 8:04pm UTC](https://forum.networklessons.com/t/introduction-to-mpls/1282 "2016-12-29T20:04:17Z")
**Posts on this page:** 1
**Showing post:** 157

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### Author: ![lagapidis](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/lagapidis/32/4949_2.png) [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [September 28, 2021, 5:29am UTC](https://forum.networklessons.com/t/introduction-to-mpls/1282/157 "2021-09-28T05:29:30Z")

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Hello Narad

> [@narad](#):
>
> Q-How many option are there to tag the label apart from LDP ??.

An MPLS network relies on end to end label switched paths (LSPs) to be established across the network. If LSPs fail, then the MPLS network will fail. LSPs are maintained most often by using the LDP protocol.

However, it is possible to configure an MPLS network to use what is known as MPLS RSVP TE (Traffic Engineering). In such a setup, [RSVP](https://networklessons.com/quality-of-service/introduction-to-rsvp) is used to set up label switched paths that can be used for TE in MPLS networks. More about this can be found in the following Cisco document:

> **[Cisco Nexus 7000 Series NX-OS MPLS Configuration Guide - Configuring MPLS TE...](https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/mpls/configuration/guide/mpls_cg/mp_te_RSVP.html#pgfId-1075546)**
>
> This chapter describes how to configure MPLS TE Resource Reservation Protocol (RSVP) on a Cisco NX-OS device.

> [@narad](#):
>
> Q-Can we configure the EIGRP,RIP,STatic route in mpls core instead of OSPF?.

It is possible to use another routing protocol within the MPLS core, or even to use static routing if you like. The important thing is to ensure that all core MPLS routers are reachable. OSPF is the routing protocol of choice however, especially for larger MPLS networks.

> [@narad](#):
>
> Q-How P router get to know that i need to perform the PHP ?.

Take a look at this post:

> [@MPLS LDP (Label Distribution Protocol)](https://forum.networklessons.com/t/mpls-ldp-label-distribution-protocol/1285/46):
>
> Hello Jack The case you are describing in your post is penultimate hop popping (PHP), which is a function performed by Label Switch Routers (LSR) before sending the packet to an adjacent Label Edge Router (LER). PHP is achieved because the LER advertises a label with a value of 3 to its neighbors. This is called an implicit-null and it is used for the LERs to inform the LSRs to perform PHP. Rene writes more about this in this post: [https://forum.networklessons.com/t/mpls-labels-and-devices/…](https://forum.networklessons.com/t/mpls-labels-and-devices/1283/18)

I hope this has been helpful!

Laz

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