Subject: [mpls] Issues with single mLDP FEC ID space

From: "BISHNOI Sandeep" <[email-masked]>
Date: Tue, 28 Jul 2009 15:44:59 -0500

MIGRATION

mLDP tree is identified by a key "root node address + 32-bit ID". On the
root node an ID is allocated out of the 32-bit pool to create an
instance of tree. Static instances of P2MP tree ID must be reserved (To
avoid dynamic and static overlap and persistency across reboots. It is
similar to current practice by each vendor to slice a specific range of
labels to support static P2P LSP. e.g. 16-1023, 10000-99999).

Each LEAF node must then configure the same specific ID selected on ROOT
node to join the tree.

e.g.

ROOT_1------------------------LEAF_1 (ROOT_1 + ID_1)

   |

   |--------------------------LEAF_2 (ROOT_1 + ID_1)

   |

   |

   |--------------------------LEAF_n (ROOT_1 + ID_1)

ROOT_1 is vendor X and has sliced the generic ID space to reserve 1-999
for static mLDP trees. LEAF_1, _2 ... _n must be configured with "ROOT_1
+ ID_1" where ID_1 is from 1-999.

ROOT_2 is vendor Y and has sliced the generic ID space to reserve
1000-1999 for static mLDP trees. LEAF_1, _2 ... _n must be reconfigured
if ROOT_1 is replaced by ROOT_2. 

The problem is particularly severe as number of leaf nodes may be in
100s and replacing a singe root node would require changing
configuration on all leaf nodes.

To keep consistency across vendors we are proposing to reserve a
complete range of ID for static mLDP trees (Type 1)

POLICY/ACCOUNTING/SECURITY

To provide flexibility to do accounting, policy management and security
across multiple client applications, we propose to extend mLDP ID space
per application. 

We fully agree that it must be optional to use application specific ID.
We propose to make a "Generic Dynamic ID space" for all dynamically
created trees (Type 2).

If the operator prefers to do accounting and policy management based on
client applications then the application specific space MAY be used.
(Type 3, 4 ... etc.). These ID spaces would be defined as and when new
applications are developed.

Statically provisioned trees still require a separate space and it would
be mandatory.