Cisco Sends Video RSVP
It's the point-to-multipoint extension to Resource Reservation Protocol-Traffic Engineering (RSVP-TE), and it's important to broadcast video services because it lets the network send multicast traffic while taking advantage of Multiprotocol Label Switching (MPLS).
Cisco will be offering the technology for its 7600 routers later this year. We know it works, because the technology was included in the recent test of Cisco's IP-video architecture that was performed by the European Advanced Networking Test Center AG (EANTC) . (See Testing Cisco's IP Video Service Delivery Network.)
The technology is described in RFC 4875, the Internet Engineering Task Force (IETF) request for comments written by representatives of Juniper, AlcaLu, and NTT Group (NYSE: NTT).
"We've had this feature running for close to two years and we have several customers using it, so it is good that Cisco is following suit," a Juniper spokesman tells Light Reading via email.
AlcaLu likewise added point-to-multipoint RSVP-TE as part of a wide-ranged router update in May, a spokeswoman says. (See AlcaLu Takes VPN Apps Into the Cloud.)
RFC 4875 uses MPLS label switched paths (LSPs) -- "tunnels," for short -- to build a point-to-multipoint tree, meaning it can take advantage of MPLS's Fast Reroute, which restores a connection within 50 milliseconds of a link failure. That's faster than the usual recovery time of 150 to 200 ms for previous multicast standards, but Cisco says the catch is that the MPLS tunnels have to be set up manually, whereas vanilla multicast creates its point-to-multipoint tree automatically.
For that reason, Cisco says RFC 4875 is best used in cases such as primary contribution networks, which move videos between studios, because the endpoints are few and they don't change. By contrast, the secondary network -- the one that carries compressed video to people's homes -- has a multitude of endpoints in dynamic flux (channels being changed).
(Juniper, by the way, disputes that RFC 4875 requires manual setup; a spokesman tells Light Reading, via email, that the point-to-multipoint LSPs, at least in Juniper's implementation, "are built using RSVP-TE signaling, which is as automatic as IP multicast.")
Lacking point-to-multipoint RSVP-TE, Cisco has been using PIM-SSM (Protocol Independent Multicast-Source Specific Multicast), which was also included in the EANTC test.
"PIM is, in our opinion and in most service providers' opinions around the world, the right decision for secondary distribution," says Mike Capuano, Cisco's director of marketing for service provider routing and switching.
AlcaLu counters, via email, by saying PIM adds management complexity to core routers, and that point-to-multipoint RSVP-TE is more flexible than PIM, letting operators "more accurately engineer where packet replication occurs in the core routers."
In any event, Capuano says carriers are only now starting to ask for point-to-multipoint RSVP-TE. So, is Cisco late with the feature? Capuano puts it this way: Cisco is adding features such as 40-Gbit/s inline monitoring of video, so the total package could be said to push Cisco past the competition.
— Craig Matsumoto, West Coast Editor, Light Reading