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Virtual Circuit Switching and MPLScse.iitkgp.ac.in/~sandipc/Courses/CS60008/MPLS.pdf · Virtual Circuit Switching and MPLS Sandip Chakraborty Department of Computer Science and Engineering,
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Packets are delivered in order, since they all take the same route
The overhead in the packets is smaller, since there is no need for eachpacket to contain the full address;
The connection is more reliable, network resources are allocated atcall setup so that even during times of congestion, provided that acall has been setup, the subsequent packets should get through;
Traffic engineering - QoS implementation becomes easier - now youcan implement RSVP over the virtucal circuit switched path!
Originally MPLS was designed to reduce IP lookups. (IP lookupoverheads associated with CIDR, longest prefix match)
Label switching reduces IP lookups - the idea was to have only thefirst router do an IP lookup, then all future routes in the networkcould do exact match “switching” based on a label.
Modern circuits can executes hundreds of IP lookups very fast, sowhy do people still care about MPLS?
Implementing Traffic-Engineering - The ability to control whereand how traffic is routed on your network, to manage capacity,prioritize different services, and prevent congestion
Implementing Multi-Service Networks - The ability to deliver datatransport services, as well as IP routing services, across the samepacket-switched network infrastructure
Improving network resiliency with MPLS “Fast Reroute”.
Prior to routing and delivery of packets in a given FEC, the LSP mustbe defined. For this purpose, two protocols are used to exchangenecessary information among the routers;
An interior routing protocol, such as OSPF, is used to exchangereachability and routing information.
Labels must be assigned to the packets for a particular FEC - LabelDistribution Protocol (LDP)
An MPLS domain consists of a contiguous, or connected set of MPLSenabled routers - we can implement virtual private network (VPN)using MPLS.
The FEC for a packet can be determined by one or more parameters,like source and destination IP address, source and destination portnumbers, IP protocol ID, differentiated service code point, IPv6 flowlabel
Forwarding is achieved by doing a simple lookup in a predefined tablethat maps label values to next hop addresses.
A particular Per-Hop Behavior (PHB) can be defined at an LSR for agtiven FEC.
Packets sent between the same endpoints may belong to differentFECs. Example: VoIP packets and VoD packets.
An MPLS domain consists of a contiguous, or connected set of MPLSenabled routers - we can implement virtual private network (VPN)using MPLS.
The FEC for a packet can be determined by one or more parameters,like source and destination IP address, source and destination portnumbers, IP protocol ID, differentiated service code point, IPv6 flowlabel
Forwarding is achieved by doing a simple lookup in a predefined tablethat maps label values to next hop addresses.
A particular Per-Hop Behavior (PHB) can be defined at an LSR for agtiven FEC.
Packets sent between the same endpoints may belong to differentFECs. Example: VoIP packets and VoD packets.
An MPLS domain consists of a contiguous, or connected set of MPLSenabled routers - we can implement virtual private network (VPN)using MPLS.
The FEC for a packet can be determined by one or more parameters,like source and destination IP address, source and destination portnumbers, IP protocol ID, differentiated service code point, IPv6 flowlabel
Forwarding is achieved by doing a simple lookup in a predefined tablethat maps label values to next hop addresses.
A particular Per-Hop Behavior (PHB) can be defined at an LSR for agtiven FEC.
Packets sent between the same endpoints may belong to differentFECs. Example: VoIP packets and VoD packets.
An MPLS domain consists of a contiguous, or connected set of MPLSenabled routers - we can implement virtual private network (VPN)using MPLS.
The FEC for a packet can be determined by one or more parameters,like source and destination IP address, source and destination portnumbers, IP protocol ID, differentiated service code point, IPv6 flowlabel
Forwarding is achieved by doing a simple lookup in a predefined tablethat maps label values to next hop addresses.
A particular Per-Hop Behavior (PHB) can be defined at an LSR for agtiven FEC.
Packets sent between the same endpoints may belong to differentFECs. Example: VoIP packets and VoD packets.
An MPLS domain consists of a contiguous, or connected set of MPLSenabled routers - we can implement virtual private network (VPN)using MPLS.
The FEC for a packet can be determined by one or more parameters,like source and destination IP address, source and destination portnumbers, IP protocol ID, differentiated service code point, IPv6 flowlabel
Forwarding is achieved by doing a simple lookup in a predefined tablethat maps label values to next hop addresses.
A particular Per-Hop Behavior (PHB) can be defined at an LSR for agtiven FEC.
Packets sent between the same endpoints may belong to differentFECs. Example: VoIP packets and VoD packets.