- New mechanisms must be developed to manage the data links, both in terms of link provisioning and fault management.
- component links are multiplex capable, whereas ports are not multiplex capable. This distinction is important since the management of such links(including, for example, resource allocation, label assignment, ant their physical verification) is different based on their multiplexing capability.
3.The link property correlation function of LMP is designed to
aggregate multiple data links (ports or component links) into a TE
link and to synchronize the properties of the TE link.
4.the Test message is the only LMP message that must be
transmitted over the data link.
5.The control channels
can be used to exchange control-plane information such as link
provisioning and fault management information (implemented using a
messaging protocol such as LMP, proposed in this document), path
management and label distribution information (implemented using a
signaling protocol such as RSVP-TE [RFC3209]), and network topology
and state distribution information (implemented using traffic
engineering extensions of protocols such as OSPF [RFC3630] and IS-IS
- OSPF is a link-state routing protocol.
- Each OSPF router maintains an identical db describing the AS’ topology. From this db, a routing table is calculated by constructing a shortest-path tree.
- OSPF recalculates routes quickly in the face of topological changes, utilizing a minimum of routing protocol traffic.
- Networks can be either transit or stub networks.
- stub networks: 桩网络，又叫末端网络，是指仅有一单个同路通过路由器连接到其他子网，或者仅有一个通路连接到其他网络。（https://www.2cto.com/net/201208/147516.html）
- Interfaces to point-to-point networks need not be assigned IP address. When interface addresses are assigned, they are modeled as sub links, with each router advertising a stub connection to the other router’s interface address.
- LSA: Link-State Advertisement(链路状态通告)
- SPF： short path first
- The topology of an area is invisible from the outside of the area. Conversely, routers internal to a given area know nothing of the detailed topology external to the area. This isolation of knowledge enables the protocol to effect a marked reduction in routing traffic as compared to treating the entire Autonomous System as a single link-state domain.
- Each area border router in an area summarizes for the area its cost to all networks external to the area. After the SPF tree is calculated for the area, routes to all inter-area destinations are calculated by examining the summaries of the are border routers.
- IP TOS field set to 0.
- The IP multicast datagrams used by OSPF never travel more than on hop.
- Supernetting has been proposed as one way to improve the scaling of IP routing in the worldwide Internet.
- OSPF simplifies this by requiring only adjacent routers to remain synchronized.
- The Designated Router is elected by the Hello Protocol.
- two-way receive: https://zhidao.baidu.com/question/1883741654782230828.html
- OSPF packet types:
- Hello Discover/maintain neighbors
- Database Description Summarize database contents
- Link State Request Database download
- Link State Update Database update
- Link State Ack Flooding ackownledgment
- using MPLS and RSVP to create a scalable traffic management architecture that supports differentiated services.
- three different traffic classes: Best Effort, Priority, and Network Control
- Network Control: routing protocols and network management traffic.
- The traffic class of MPLS packets can be encoded in the three bits reserved for CoS.
- traffic classes for IPv4 packets can be classified via the IPv4 ToS byte.
- As the traffic scales up, the amount of traffic in the trunks increases; not the number of trunks.
- RSVP mechanisms: a. provide a general facility for creating and maintaining distributed reservation state across a mesh of multicast or unicast delivery paths; b. provides a straightforward extensibility mechanism by allowing for creation of new RSVP objects.
- TE is necessary because standard IGPs compute the shortest path across the ISP’s network based solely on the metric that has been administratively assigned to each link. This computation does not take into account the loading of each link.