The MPLS WG Archive

["john151@libero.it" <john151@libero.it>]

Hi William hi all,
I intended for protected LSP an LSP with one (or more ) backup associated Path.
Then i see no changing in the way of establishing them in relation to what we already have (RSVP...)

Thanks in advance for your kind answers and observations.

Giovanni di Giacomo





 John/ Giovanni

The theory sounds interesting , the first thing that struck me is the term
"protected LSPs". In your second item you state that there arent that many ,
I want to know what protection mechanism is in place to establish them ?
Will

-----Original Message-----
From: john151@libero.it
To: mpls
Sent: 3/13/03 10:43 AM
Subject: Observations OSPF RSVP... 

Hi all,

i see at least two advantages in using Opaque LSA insted of PathErr
(quite the same for the Notifies ) in this scenario: precalculated and
presignalled backup disjoint paths for protected LSPs in MPLS Network,
availability of fast detection mechanism ( from lower levels ) of link
failure.

1) Since Opaque LSAs don' t trigger an SPF calculation in the routers
they cross, all the Network is soon informed about the link failure
event and IN PARALLEL each router can do the label switching on the
backup LSPs ( after having controlled the presence of protected LSPs
starting from it and interested by the link failure ). 

2) Since i refer to protected LPSs ( they are relatively few ), thinking
in a scenario in which there should be a return to the first active LSP
when the link failed returns to be UP ( that is a second switch from
backup LSP to the  first active LSP ), could it be not necessary to send
the PathTears immediately to cleanup resources? This will bring two
beneficts: no PathTears and ResvTear sent immediately in  the Network
and no signalling messages storm when the link returns up ( after a not
long period ), when it's probable that all the backup LSPs will return
on that link (the link that went down). 

Thanks in advance for your kind answers and observations.

Giovanni di Giacomo