[j-nsp] Fast Reroute

[alaerte vidali]

Hi,

Trying to clarify Junos protection when comparing with Cisco:

"
Multiprotocol Label Switching (MPLS) fast reroute (FRR) refers to local
protection methods such as one-to-one and many-to-one (facility) backup. In
the general networking community, the term FRR has become a shorthand way of
describing the entire spectrum of MPLS traffic protection mechanisms. This
should not be confused with the JUNOS software fast reroute feature. In this
book, the acronym FRR is used to describe general MPLS traffic protection,
while the distinct JUNOS software feature is described as fast reroute.
"

As you know, Cisco FRR is many-to-one protection, provided by the
fastreroute command on the TE tunnel and backup command on interface level.
Node protection is achieved in similar way (requiring fast reroute on TE
tunnel and configuring protection on interface), just making sure the backup
path is NNHOP.

Going further on Juniper definition:

"
Local protection in the JUNOS software is described as follows:

   - One-to-one (fast reroute) backup—A router upstream from a failure
   quickly builds a detour LSP around the failure to the router downstream from
   the failure, providing protection against link or node failure. The upstream
   router then signals the outage to the ingress router, thereby maintaining
   connectivity before a new LSP is established. You can configure one-to-one
   backup by including the fast-reroute statement at the [edit protocols
   mpls label-switched-path *path-name*] hierarchy level. For more
   information about configuring and verifying one-to-one backup, see
Configuring
   and Verifying One-to-One
Backup<http://www.pacband.com/techpubs/software/nog/nog-mpls-frr/html/local-protection4.html#1197089>
   .
   - Link protection (many-to-one or facility backup)—Each router
   establishes a bypass LSP to its neighbor, avoiding the link connecting them,
   and ensuring traffic flow for the LSP when a link connecting two nodes
   fails. You can configure many-to-one backup by including the
   link-protection statement at the [edit protocols mpls
   label-switched-path *path-name*] hierarchy level. For more information
   about configuring and verifying link protection, see Configuring and
   Verifying Link
Protection<http://www.pacband.com/techpubs/software/nog/nog-mpls-frr/html/local-protection8.html#1197199>
   .
   - Node-link protection (many-to-one or facility backup)—Each router
   dynamically signals a bypass LSP and determines if the protected LSP needs a
   node bypass or a link bypass, thereby ensuring traffic flow when a node or
   link in the LSP fails. You can configure node-link protection by including
   the node-link-protection statement at the [edit protocols mpls
   label-switched-path *path-name*] hierarchy level. To enable node-link
   protection, you must also include the link-protection statement at the
   [edit protocols rsvp interface *interface-name*] hierarchy level. For
   more information about configuring and verifying node-link
protection, see Node-Link
   Protection Overview<http://www.pacband.com/techpubs/software/nog/nog-mpls-frr/html/local-protection11.html#1074916>
   .

 The important difference between using the fast-reroute statement and
either of the link-protection statements is that the fast-reroute statement,
regardless of whether a link or node fails, always protects one LSP with one
detour path. The link-protection and node-link-protection statements always
protect any LSPs crossing the node with one bypass path.

There are a couple of things to consider when deciding to configure fast
reroute or link protection. The first is interoperability with equipment
from other vendors, for example, Cisco Systems supports FRR, but does not
support one-to-one backup. The second is that protection paths consume
forwarding resources. In this regard, facility backup has better scaling
because the protection paths are shared.

"

So, is it safe to say that Juniper link-protection (many to one) is the same
as Cisco fastreroute and Junos Node-link protection is the same as Cisco
fastreroute when NNHOP is used?

Thanks,
Alaerte