This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: 6.7 Resilient Packet Ring 421 connection. T-MPLS reuses the architecture of MPLS and simplifies it for transport. It adds features to support bidirectional connections, since MPLS is a unidirectional technology. Since T-MPLS connections are expected to have very long lifetimes, T-MPLS has protection switching and operations and management not found in ordinary MPLS (see Section 9.3.4 on protection switching). Due to concerns over the compatibility of Transport MPLS with MPLS, development of T-MPLS has been halted and work on a new MPLS has begun, called MPLS-Transport Profile (MPLS- TP). This new development will likely incorporate some of the aspects of T-MPLS. 6.7 Resilient Packet Ring Resilient Packet Ring (RPR) is a packet-switched ring network that transports data packets such as IP packets. It has application as a metropolitan- or wide-area net- work. RPR provides different services. It has guaranteed bandwidth to emulate constant-bit-rate, low delay service, and it has fair access for best-effort service. The ring network topology is resilient to failures, and in particular it remains connected after single-link or single-node failures. The RPR failure recovery mechanism is dis- cussed in Section 9.3.1, which is designed to have restoration times of 50 ms. RPR is at the link layer just like Ethernet. It has its own frames, which are described in [DYGU04]. It can be mapped into the Gigabit Ethernet physical layer, the 10-Gigabit Ethernet physical layer, or SONET/SDH frames. The ring network is bidirectional formed by two counter-rotating rings called Ringlets 0 and 1, as shown in Figure 6.24, where the links have the same capacities. A source node sends an RPR frame to its destination by inserting it into one of ringlets. The frame is then forwarded by intermediate nodes until it reaches its destination node, where it is switched out of the ringlet. Note that there are two types of frames: transit frames , which have accessed a ringlet, and ingress frames , which are new frames that are waiting to be added into a ringlet....
View Full Document
This note was uploaded on 01/15/2011 for the course ECE 6543 taught by Professor Boussert during the Spring '09 term at Georgia Tech.
- Spring '09