What is CSPF in MPLS?
Constrained Shortest Path First (CSPF) is an extension of shortest path algorithms. The path computed using CSPF is a shortest path fulfilling a set of constraints. CSPF is widely used in MPLS Traffic Engineering. The routing using CSPF is known as Constraint Based Routing (CBR).
What is Shortest Path First algorithm?
Also called the Dijkstra algorithm, SPF is a routing algorithm in which a router computes the shortest path between each pair of nodes in the network. The Open Shortest Path First (OSPF) Protocol is based on the Shortest Path First (SPF) algorithm.
What is a path in RSVP?
When a PATH message is received, the RSVP SP creates an RSVP session and associates a PATH state (based on the PATH message) with the RSVP session. The RSVP SP sends RESV messages once it determines that the PATH state exists for a session that matches a socket for which receiving QOS is indicated.
What is the difference between LDP and RSVP-TE?
2 commonly used terms in MPLS are LDP and RSVP-TE….LDP vs RSVP.
| PARAMETER | LDP | RSVP |
|---|---|---|
| Requirement | If primarily LSPs need to be set up, LDP should be used | If you require traffic engineering and resources reservations, use RSVP (-TE). |
| Scalability | High | Low |
| ECMP | Possible | Not Possible |
| Fast Reroute (FRR) support | No | Yes |
How is Cspf calculated?
- 1) Definition.
- EER: Energy Efficiency Ratio.
- = Cooling capacity ÷ Power input.
- (usually only at 35℃）
- CSPF: Cooling Seasonal Performance Factor.
- (SEER: Seasonal Energy Efficiency Ratio)
- = Total cooling load ÷ Total power consumption.
How does MPLS LDP work?
LDP is a protocol that automatically generates and exchanges labels between routers. Each router will locally generate labels for its prefixes and will then advertise the label values to its neighbors.
How LDP works in MPLS?
MPLS LDP enables one LSR to inform another LSR of the label bindings it has made. Once a pair of routers communicate the LDP parameters, they establish a label-switched path (LSP). MPLS LDP enables LSRs to distribute labels along normally routed paths to support MPLS forwarding.
What is LDP over RSVP?
LDP over RSVP Using OSPF as IGP. This section provides information about Label Distribution protocol (LDP) over Resource Reservation Protocol for Traffic Engineering (RSVP-TE), also called LDPoRSVP, that uses RSVP Label Switched Paths (LSPs) as a transport vehicle to carry the packets using LDP LSPs.
When to use CSPF in computing LSP paths?
CSPF is used in computing paths for LSPs that are subject to multiple constraints. When computing paths for LSPs, CSPF considers not only the topology of the network, but also the attributes of the LSP and the links, and it attempts to minimize congestion by intelligently balancing the network load. The constraints that CSPF considers include:
How does CSPF calculate the route to the destination?
But think of them as the GPS and the engine: “CSPF calculates the route to the destination, and RSVP sets up a path following that route, so that traffic can be forwarded.” I’ll go over the details of how this happens, but as always, before we jump into the details, let’s review some basics and get some context, so that things make sense.
When does MPLS perform constrained-path LSP computation?
If IS-IS is enabled on a router or you enable OSPF traffic engineering extensions, MPLS performs the constrained-path LSP computation by default. For information about how constrained-path LSP computation works, see Constrained-Path LSP Computation.
How are LSPs set up in MPLS Traffic Engineering?
That’s the foundation of MPLS traffic engineering: The ability to set up a path that is different from what the local IGP considers the optimum path between the ingress and egress, as shown in Figure 1. In fact, different LSPs between the same two endpoints can take different paths.