The MPLS WG Archive

[JP Vasseur <jvasseur@cisco.com>]

Hi,

Note sure where to start ....

First comment, you pointed out potential weaknesses of both IPFRR and MPLS TE FRR that actually are incorrect ....

You write:

The characteristics of IP FRR is that it performs the reroute according 
to the port state and the backup ports are configured manually, so the 
optimization can't be guaranteed in the case of complex network 
topology, what's more, when the configured backup port is in failure 
prior to the primary port, even there are other ports can function as 
backup port, they can't be used as rerouting.

Both statement are actually incorrect ! The backup path can be computed dynamically of course.

MPLS network need FRR to protect the traffic transported on MPLS LSP in 
the case of link or node failure, and in [2]
draft-ietf-mpls-rsvp-lsp-fastreroute-07, the MPLS fast rerouting 
mechanism of extension to RSVP-TE is detailed, it requires that RSVP-TE 
is deployed as the label distribution protocol in the network, however, 
in some network, LDP rather than RSVP-TE is deployed as label 
distribution protocol, so FRR based on RSVP-TE can't be performed; 

Note that their deployment is not exclusive

another point is that the backup LSP in RSVP-TE FRR is manually 
configured, so the configuration job is such a burden in large scale 
network; moreover, to protect the link, node or path respectively, the 
different backup LSP are accordingly required, which will consume a 
large amount of resource in the network. In this section, a simple MPLS 
FRR mechanism based on LDP(called MPLS mini-FRR) is introduced.

No ! the backup tunnel path can be configured dynamically (even including many other constraints such as SRLG membership). Note that there are several implementations supporting this. And of course, the FRR document does not mandate to manually configure the backup tunnels by all means,

2) Note that the two previous scheme are local protection schemes.

3) More importantly ... your mini-FRR scheme works well on a mini-topology ....

In your example, please try the two following changes:

-> make the shortest path from R3 to R5 be: R3-R1-R2-R5
-> insert a router between R2 and R3 so that R3 cannot detect the R2's failure.

?

Thanks.

JP.
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