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22. 10. 2007 T-110. 5110 Computer Networks II Quality of Service 20. 10. 2008 22. 10. 2007 T-110. 5110 Computer Networks II Quality of Service 20. 10. 2008 Dr. Matti Siekkinen [email protected] hut. fi (Primary sources: C. Hota: “Quality of Service in the Internet” and J. Manner: IP Quality of Service)

Outline q What is Qo. S? q Qo. S mechanisms q Qo. S architectures Outline q What is Qo. S? q Qo. S mechanisms q Qo. S architectures § § § 2 Integrated Services (Int. Serv) Differentiated Services (Diff. Serv) Multiprotocol Label Switching (MPLS) Generalized Multiprotocol Label Switching (GMPLS) Qo. S architectures for mobile networks Next Steps in Signaling (NSIS) 3/18/2018 22. 10. 2007

What is Quality of Service? q Many applications are sensitive to delay, jitter, and What is Quality of Service? q Many applications are sensitive to delay, jitter, and packet loss § Too high values makes utility drop to zero q Some mission-critical applications cannot tolerate disruption § Vo. IP § high-availability computing q Charge more for business applications vs. consumer applications q Related concept is service availability § How likely is it that I can place a call and not get interrupted? § requires meeting the Qo. S requirements for the given application 3 3/18/2018 22. 10. 2007

Qo. S Requirements Sensitive Personal voice over IP CEO Video conference with analysis Network Qo. S Requirements Sensitive Personal voice over IP CEO Video conference with analysis Network monitorin g Unicast radio Financial Transactions Interactive whiteboar d Delay Public web traffic Extranet web traffic Network management traffic Push news Personal e-mail Busines s e-mail Server backups Insensitive Casual 4 Mission Criticality 3/18/2018 Critical 22. 10. 2007

Qo. S and the Internet q The existing Internet architecture provides a best effort Qo. S and the Internet q The existing Internet architecture provides a best effort service. § All traffic is treated equally (generally, FIFO queuing with tail drop) § No mechanism for distinguishing between delay sensitive and best effort traffic § No guarantees for end-to-end Qo. S q Originally IPv 4 has TOS (type-of-service byte) in packet header § RFC 795: defined multiple axes (delay, throughput, reliability) § rarely used in practice (Diff. Serv) q We try to minimize delay and loss § …and try to mitigate the effects with different techniques § E. g. adapt application (video stream) based on Qo. S feedback (RTCP) 5 3/18/2018 22. 10. 2007

Outline q What is Qo. S? q Qo. S mechanisms q Qo. S architectures Outline q What is Qo. S? q Qo. S mechanisms q Qo. S architectures § § § 6 Integrated Services (Int. Serv) Differentiated Services (Diff. Serv) Multiprotocol Label Switching (MPLS) Generalized Multiprotocol Label Switching (GMPLS) Qo. S architectures for mobile networks Next Steps in Signaling (NSIS) 3/18/2018 22. 10. 2007

Qo. S Mechanisms Packet Scheduling Traffic Shaping (Users get their share of bandwidth) (Amount Qo. S Mechanisms Packet Scheduling Traffic Shaping (Users get their share of bandwidth) (Amount of traffic users can inject into the network) Admission Control (To accept or reject a flow based on flow specifications) 7 Core 3/18/2018 22. 10. 2007

Qo. S Mechanisms: classification q Provisioning § Admission control o Prohibit or allow new Qo. S Mechanisms: classification q Provisioning § Admission control o Prohibit or allow new flows to enter the nw § Resource reservation o E. g. Over provisioning q Control § Operate on short time scales § Real-time traffic or flow control o E. g. scheduling, shaping, policing. . . q Management § Monitor the Qo. S § Longer time scales than control 8 3/18/2018 22. 10. 2007

Qo. S Control Mechanisms q Application-level techniques § Application adapts to network conditions § Qo. S Control Mechanisms q Application-level techniques § Application adapts to network conditions § E. g. adapt media stream to a lower quality based on RTCP feedback q Transport-layer techniques § Adapt transport protocols to application requirements and network conditions § TCP, DCCP q Network-layer techniques § Qo. S routing § Non-FIFO scheduling (like WFQ) § Something else than tail drop (like RED) 9 3/18/2018 22. 10. 2007

Qo. S Control Mechanisms (cont. ) IP addresses, net mask, port numbers, protocol id Qo. S Control Mechanisms (cont. ) IP addresses, net mask, port numbers, protocol id Arrival Full Packet Classifier Y N Processor Departure Queue Discard Scheduling (FIFO Queuing) Flow identifier Full Arrival Classifier Y Discard Full The switch turns to other queue when the current one is empty N High Priority Queue Processor N Y Discard Departure Low Priority Queue Scheduling (Priority Queuing) 10 3/18/2018 22. 10. 2007

Qo. S Control Mechanisms (cont. ) Full Arrival Classifier N Y Discard Full The Qo. S Control Mechanisms (cont. ) Full Arrival Classifier N Y Discard Full The turning switch selects 2 packets from 1 st queue, then 1 packet from 2 nd queue and the cycle repeats Weight: 2 Processor N Y Discard Departure Weight: 1 Scheduling (Weighted Fair Queuing) Leaky Bucket (Regulate the traffic) 11 3/18/2018 Token Bucket (Credit an idle host) 22. 10. 2007

Qo. S Control Mechanisms (cont. ) Arriving Packet Queue Accepted Dropped from front Full Qo. S Control Mechanisms (cont. ) Arriving Packet Queue Accepted Dropped from front Full (Tail-drop scheme) (Drop-from-front scheme) Drop probability Queue 1 Avg. TCP Traffic Drop MAXth MINth MAXdrop MINth (Random Early Detection with Drop function) 12 3/18/2018 MAXth Avg. queue size 22. 10. 2007

Qo. S Control Mechanisms (cont. ) q Qo. S routing § Routing based on Qo. S Control Mechanisms (cont. ) q Qo. S routing § Routing based on Qo. S related metrics, not just shortest path o E. g. available bandwidth § (Multi-)constrained path computation o Can be computationally complex § Widest-Shortest Path o Select the shortest path that is feasible according to the bandwidth constraint § Shortest-Widest Path Find paths with the most available bandwidth (i. e. widest paths) o Break ties by selecting the shortest path (#hops or delay) o 13 3/18/2018 22. 10. 2007

Where to implement Qo. S mechanisms? q Core routers § Link speeds fast § Where to implement Qo. S mechanisms? q Core routers § Link speeds fast § Lot of traffic èCannot do much more than over provisioning or treat limited nb of flow classes q Access routers § Generally, not so high rates § Feasible to do complex operations (filtering, classification, policing…) èCould do per-flow packet handling 14 3/18/2018 22. 10. 2007

Outline q What is Qo. S? q Qo. S mechanisms q Qo. S architectures Outline q What is Qo. S? q Qo. S mechanisms q Qo. S architectures § § § 15 Integrated Services (Int. Serv) Differentiated Services (Diff. Serv) Multiprotocol Label Switching (MPLS) Generalized Multiprotocol Label Switching (GMPLS) Qo. S architectures for mobile networks Next Steps in Signaling (NSIS) 3/18/2018 22. 10. 2007

Qo. S Architectures q Use the Qo. S mechanisms to provide application to application Qo. S Architectures q Use the Qo. S mechanisms to provide application to application Qo. S q Many different proposals over the years § YESSIR, Int. Serv, Diff. Serv, Mobile RSVP, OMEGA, Qo. S-A. . . q We will look at a few ones in more detail § Integrated Services (Int. Serv) § Differentiated Services (Diff. Serv) § Multiprotocol Label Switching (MPLS) § Generalized MPLS (GMPLS) § Qo. S for mobile networks § Next Steps in Signaling (NSIS) 16 3/18/2018 22. 10. 2007

Int. Serv q Resource reservation and admission control q Source describes its desired flow Int. Serv q Resource reservation and admission control q Source describes its desired flow rate and sends this information to the routers and the receiver q Network admits requests and reserves resources q Source must send at this rate (controlled by network) q Provides a sort of “dedicated” connection within an IP packetswitched network q Reservation of resources is done with the Resource Reservation Protocol (RSVP) 17 3/18/2018 22. 10. 2007

RSVP q Supports both multicast and unicast q Sender-to-network signaling § path message: make RSVP q Supports both multicast and unicast q Sender-to-network signaling § path message: make sender presence known to routers § path teardown: delete sender’s path state from routers q Receiver-to-network signaling § reservation message: reserve resources from senders to receiver § reservation teardown: remove receiver reservations q Network-to-end-system signaling § path error, -reservation error q Soft state protocol § Need to refresh state 18 3/18/2018 22. 10. 2007

RSVP (cont. ) q Reservations are for unidirectional data flows q Provides several reservation RSVP (cont. ) q Reservations are for unidirectional data flows q Provides several reservation models or "styles" to fit a variety of applications (shared and dedicated reservations) q Transparent to routers that do not support it § RSVP packets are just normal IP packets q Not a routing protocol but depends upon present and future routing protocols q Supports both IPv 4 and IPv 6 19 3/18/2018 22. 10. 2007

Int. Serv: Scalability Issues q RSVP signaling Overhead § One PATH/RESV per flow for Int. Serv: Scalability Issues q RSVP signaling Overhead § One PATH/RESV per flow for each refresh period q Processing overhead § Routers have to classify, police and queue each flow q State information stored in routers § Flow identification (using IP address, port etc) § Previous hop identification § Reservation Status § Reserved Resources 20 3/18/2018 22. 10. 2007

Diff. Serv q No signalling, no resource reservation q Complex processing is moved from Diff. Serv q No signalling, no resource reservation q Complex processing is moved from core to edge q Per flow service (Int. Serv) is replaced by per aggregate or per class service with a SLA with the provider q Mark packets with a code (DSCP) to differentiate between pkts/flows § e. g. a priority stamp § Uses IP type of service field (TOS) q Core uses the codes to select appropriate service level § Premium, priority, best effort 21 3/18/2018 22. 10. 2007

Diff. Serv q Two types of services standardized, operators may define other services and Diff. Serv q Two types of services standardized, operators may define other services and code points q Does not necessarily provide end-to-end Qo. S: § Operators may have different meanings and implementations for classes and code points, § The code points can change, thus, may not remain the same on the whole end-to-end path. 22 3/18/2018 22. 10. 2007

Diff. Serv Schema q Source sends request message to first hop router q First Diff. Serv Schema q Source sends request message to first hop router q First hop router sends request to Bandwidth Broker (BB) that replies with either accept or reject q If the request is accepted, either the source or the first hop router will mark DSCP and will start sending packets q Edge router checks compliance with the SLA and will do policing. It may drop or mark the packet with low priority to match the SLA q Core routers will look into DSCP and decide the PHB 23 3/18/2018 22. 10. 2007

Expedited Forwarding • • 24 Expedited packets experience a traffic-free network (low loss, low Expedited Forwarding • • 24 Expedited packets experience a traffic-free network (low loss, low latency, low jitter, and assured bandwidth (premium service) Strict priority queuing 3/18/2018 22. 10. 2007

Assured Forwarding • • AF PHB delivers the packet with high assurance as long Assured Forwarding • • AF PHB delivers the packet with high assurance as long as its class does not exceed the a subscribed rate • 25 A possible implementation of the data flow for assured forwarding is shown below. Use e. g. WFQ scheduling with RED 3/18/2018 22. 10. 2007

Bandwidth Brokers U 1 BB S 1 U 2 BB C 1 S 2 Bandwidth Brokers U 1 BB S 1 U 2 BB C 1 S 2 C 2 ISP 2 D Server 3 C 6 Core Network C 7 Server 2 Server 1 U 2 26 BB C 5 C 4 ISP 1 BB BB U 3 3/18/2018 22. 10. 2007

Integrated Solution 27 3/18/2018 22. 10. 2007 Integrated Solution 27 3/18/2018 22. 10. 2007

Multiprotocol Label Switching (MPLS) q Traffic engineering tool § Allocate specific path and network Multiprotocol Label Switching (MPLS) q Traffic engineering tool § Allocate specific path and network resources to specific types of traffic ensuring Qo. S q Supports multiple protocols § IPv 4, IPv 6, IPX, Apple. Talk at the network layer § Ethernet, Token Ring, FDDI, ATM, Frame Relay, PPP at the link layer q Forwarding behavior independent of layer 2 and layer 3 q Data transmission occurs on Label Switched Paths (LSP) q Labels are distributed using Label Distribution Protocol (LDP), or RSVP, or piggybacked on BGP and OSPF q FEC (Forward Equivalence Class) is a representation of group of packets that share the same requirements for their transport q Assignment of FEC to a packet is done once only as it enters into the network 28 3/18/2018 22. 10. 2007

Model for MPLS Network • Convergence of connection oriented forwarding techniques and Internet’s routing Model for MPLS Network • Convergence of connection oriented forwarding techniques and Internet’s routing protocols LER LSR = Label Switched Router LER = Label Edge Router LSP = Label Switched Path LSR LSP Route at edge and Switch at core 29 3/18/2018 22. 10. 2007

Separate forwarding and control • Exact match instead of longest prefix match (like IP) Separate forwarding and control • Exact match instead of longest prefix match (like IP) è faster forwarding IP Router Control: IP Router Software MPLS Control: IP Router Software ATM Switch Control: ATM Forum Software Forwarding: 30 Forwarding: Longest-match Lookup Label Swapping 3/18/2018 22. 10. 2007

MPLS Forwarding 31 3/18/2018 22. 10. 2007 MPLS Forwarding 31 3/18/2018 22. 10. 2007

MPLS Operation 1 a. Routing protocols (e. g. OSPF-TE) exchange reachability to destination networks MPLS Operation 1 a. Routing protocols (e. g. OSPF-TE) exchange reachability to destination networks 4. LER at egress removes label and delivers packet 1 b. Label Distribution Protocol (LDP) establishes label mappings to destination network IP Ingress IP 20 IP 10 IP IP 40 Egress MPLS Domain 2. Ingress LER receives packet and “label”s packets 32 3/18/2018 3. LSR forwards packets using label swapping 22. 10. 2007

MPLS Labels • Label assignment decisions are based on forwarding criteria like • Destination MPLS Labels • Label assignment decisions are based on forwarding criteria like • Destination unicast routing • Traffic engineering • Multicast • Virtual Private Network • Quality of Service 33 A Label could be embedded in the header of the DL layer like ATM (VPI/VCI) and FR (DLCI) or could be between DL and IP as shown below: Bottom of Stack (first label in stack) 3/18/2018 22. 10. 2007

Label and FEC Relationship R 4 could send a packet with Label=L 1, but Label and FEC Relationship R 4 could send a packet with Label=L 1, but it would mean a different FEC Assignment of FEC to a packet is done by ingress router • FEC (Forwarding Equivalence Class): Assigned on the basis of IP addresses, port numbers or TOS bits. • FEC could be associated with all the flows destined to an egress LSR. 34 3/18/2018 22. 10. 2007

Label Merging q Label Switched Path (LSP): A unidirectional connection through multiple LSRs. 3 Label Merging q Label Switched Path (LSP): A unidirectional connection through multiple LSRs. 3 7 6 A B 5 E C 2 8 5 D A 5 6 F E 6 3 B C 8 D 5 6 F Multi-point to Single point tree routed at Egress router 35 3/18/2018 22. 10. 2007

LSP Hierarchy q A Packet can have several labels one after the other before LSP Hierarchy q A Packet can have several labels one after the other before the IP header. (Why? Tunneling) (Multiple Levels of Nesting) (Tunnel 1 may be for the Enterprise with 1 a for Vo. IP data, 1 b for billing, and 1 c for alarm & provisioning) Push Swap & Push R 1 R 2 A Swap R 2 B Pop & Swap Pop R 2 C R 3 R 4 IP 36 3 2 7 23/18/2018 8 6 2 4 IP 22. 10. 2007

Label Distribution q Establishes and Maintains a LSP that includes establishment of Label/FEC bindings Label Distribution q Establishes and Maintains a LSP that includes establishment of Label/FEC bindings between LSRs in the LSP. q A downstream LSR can directly distribute Label/FEC (unsolicited downstream). q An upstream LSR requests a downstream for Label/FEC (downstream on demand). q Protocols like LDP, RSVP-TE are used to distribute Labels in the LSP 37 3/18/2018 22. 10. 2007

Label Distribution q Label Distribution Protocol (LDP) [RFC 3036] § An LSR sends HELLO Label Distribution q Label Distribution Protocol (LDP) [RFC 3036] § An LSR sends HELLO messages over UDP periodically to its’ neighbors to discover LDP peers (routing protocol tells about peers) § Upon discovery, it establishes a TCP connection to its peer § Two peers then may negotiate Session parameters (label distribution option, valid label ranges, and valid timers) § They may then exchange LDP messages over the session (label request, label mapping, label withdraw etc) q RSVP-TE (Resource Reservation Protocol-Traffic Extension) [RFC 3209] § Path message includes a label request object, and Resv message contains a label object § Follows a downstream-on-demand model to distribute labels § Path message could contain an Explicit Route Object (ERO) to specify list of nodes § Priorities can be assigned to LSPs, where a higher one can preempt a lower one 38 3/18/2018 22. 10. 2007

MPLS Protection q Dynamic routing restores the traffic (upon a failure) based on the MPLS Protection q Dynamic routing restores the traffic (upon a failure) based on the convergence time of the protocol § Convergence can be slow q Set up secondary backup paths in addition to primary working paths § End-to-end protection q May need really fast recovery for mission critical or high priority data § Fast reroute: Setup detour paths around failed links/nodes § Temporary recovery until backup path takes over 39 3/18/2018 22. 10. 2007

Int. Serv, Diff. Serv and MPLS q An RSVP request (say guaranteed service) from Int. Serv, Diff. Serv and MPLS q An RSVP request (say guaranteed service) from one domain could be mapped to an appropriate Diff. Serv PHB at another domain that again could be mapped to a possible MPLS FEC at the edge of another MPLS domain. 40 3/18/2018 22. 10. 2007

Generalized MPLS (GMPLS) q MPLS – the base technology (for packet switched nws) q Generalized MPLS (GMPLS) q MPLS – the base technology (for packet switched nws) q GMPLS – extension of MPLS to provide the control plane (signaling and routing) for devices that switching in any of these domains: packet, time, wavelength and fiber. 41 3/18/2018 22. 10. 2007

MPLS vs. GMPLS q For packet-switching nw only q Focuses mainly on the data MPLS vs. GMPLS q For packet-switching nw only q Focuses mainly on the data plane 42 GMPLS q For packet switched capable (PSC) as well as non-PSC interfaces. q Focuses on the control plane that performs connection management for the data plane 3/18/2018 22. 10. 2007

MPLS vs. GMPLS (cont. ) MPLS GMPLS q Requires Label Switched Path (LSP) to MPLS vs. GMPLS (cont. ) MPLS GMPLS q Requires Label Switched Path (LSP) to be set up b/w routers at both ends 43 q LSP can be set up b/w any similar types of Label Switched Routers (LSR) e. g. b/w SONET/SDH ADM to form a TDM LSP q Scale better by forming a forwarding hierarchy q Functions specific to optical nw such as suggested label and bi-directional LSP setup 3/18/2018 22. 10. 2007

Goals of GMPLS q A common control plane promises to simplify network operation and Goals of GMPLS q A common control plane promises to simplify network operation and management by: § Automating end-to-end provisioning of connections § Managing network resources 44 3/18/2018 22. 10. 2007

Summary of the GMPLS Protocol Suite q Extended the signaling (RSVP-TE, CR-LSP) and routing Summary of the GMPLS Protocol Suite q Extended the signaling (RSVP-TE, CR-LSP) and routing protocols (OSPF-TE, IS-IS-TE) to accommodate the characteristics of TDM/SONET & optical networks. q A new protocol, Link Management Protocol (LMP) has been introduced to manage and maintain the health of the control and data planes between two neighboring nodes. 45 3/18/2018 22. 10. 2007

LSP Creation in GMPLS-Based Networks / Hierarchical LSP 1. LSP (LSPλ) is established between LSP Creation in GMPLS-Based Networks / Hierarchical LSP 1. LSP (LSPλ) is established between OXC 1 and OXC 2 and capable of delivering OC-192 wavelength to tunnel in TDM LSPs. 2. LSP (LSPtdi) is established between DCSi and DCSe. 3. LSP (LSPtdm) is established between DCS 1 and DCS 2. 4. LSP (LSPpi) is established between LSR 2 and LSR 3 (LSPpi). 5. 46 LSP (LSPpc) is established between LSR 1 and LSR 4. 3/18/2018 22. 10. 2007

Qo. S for Mobile Networks q Problems: § § Current IP Qo. S Signaling Qo. S for Mobile Networks q Problems: § § Current IP Qo. S Signaling is not mobility aware (RSVP, Diff. Serv etc) Resources may not be available for the new path Handoff latency Different Qo. S mechanisms q Requirements/challenges: § Minimize disruption in Qo. S during handover § Localize the Qo. S re-establishment to only the effected parts of the packet path § Release any old Qo. S state after handover as early as possible § Deal with multiple Qo. S mechanisms deployed q Mobile RSVP (MRSVP) § Use advance resource reservations § Common path identification § Mobile proxy: refresh RSVP state instead of energy constrained mobile device 47 3/18/2018 22. 10. 2007

Qo. S for MANETs q More problems: § No infrastructure, all mobile battery limited Qo. S for MANETs q More problems: § No infrastructure, all mobile battery limited devices § Frequent topology changes and high mobility q INSIGNIA § Support for the delivery of adaptive services in mobile ad hoc networks § See Seoung-Bum Lee et al. INSIGNIA: An IP-Based Quality of Service Framework For Mobile Ad Hoc Networks, Journal of Parallel and Distributed Computing, 2000. 48 3/18/2018 22. 10. 2007

Next Steps in Signaling (NSIS) q RSVP not widely used for resource reservation § Next Steps in Signaling (NSIS) q RSVP not widely used for resource reservation § Used for MPLS path setup § Security an open issue § Limited support for IP mobility q IETF NSIS working group is looking at new ways to do Qo. S signaling § Re-use, where appropriate, the mechanisms of RSVP § See e. g. rfc 4080 49 3/18/2018 22. 10. 2007

References 1. Andrew S. Tanenbaum, Computer Networks, Fourth Edition, Pearson Education, 2006. 2. James References 1. Andrew S. Tanenbaum, Computer Networks, Fourth Edition, Pearson Education, 2006. 2. James F. Kurose, and Keith W. Ross: Computer Networking: A Top-Down Approach Featuring the Internet, Third Edition, Pearson Education, 2006. 3. Alberto Leon-Garcia and Indra Widjaja, Communication Networks: Fundamental Concepts and Key Architectures, Second Edition, Tata Mc. Graw-Hill, 2005. 4. IP Qo. S Architectures and Protocols, Packet Broadband Network Handbook, Digital Engineering Library, Mc. Graw Hill, 2004. 5. Congestion Control and Quality of Service, Data Communication and Networking, Digital Engineering Library, Mc. Graw Hill, 2006. Curado, M. and Monteiro, E. , "A Survey of Qo. S Routing Algorithms", in Proc. of the International Conference on Information Technology (ICIT 2004), December 2004 7. Manner Jukka, Lopez A, Mihailovi A, Velayos H, Hepworth E, and Y Khouaja, Evaluation of Mobility and Qo. S Interaction, Computer Networks Volume 38, Issue 2, 5 Feb 2002, pp. 137 -163. 8. Anup Kumar Talukdar, B. R. Badrinath, and Arup Acharya, MRSVP: A Resource Reservation Protocol for an Integrated Services Network with Mobile Hosts, Wireless Networks, 7, 5– 19, 2001. 9. Rajeev Koodli, and Charles E. Perkins, Fast Handovers and Context Transfers in Mobile Networks, ACM SIGCOMM Computer Communications Review, Special Issue on Wireless Extensions to Internet, 2001. 10. J. Hillebrand, C. Prehofer, R. Bless, M. Zitterbart, Quality-of-Service Signaling for Next-Generation IP-based Mobile Networks, IEEE Communications Magazine, June 2004. 11. Seoung-Bum Lee, G. Ahn, X. Zhang and A. T. Campbell, INSIGNIA: An IP-Based Quality of Service Framework For Mobile Ad Hoc Networks, Journal of Parallel and Distributed Computing, 2000. 12. Chittaranjan Hota, Sanjay Jha, G Raghurama, Distributed Dynamic Resource Management in IP VPNs to Guarantee Quality of Service, IEEE ICON 2004, Singapore. 13. RFC 2205: Resource Reservation Protocol, Braden, Zhang et al. 14. RFC 3031: Multiprotocol Label Switching (MPLS), Rosen, Viswanathan and Callon. 15. RFC 2475: An Architecture for Differentiated Services, S. Blake, D. Black et al. 16. RFC 4080: Next Steps in Signaling (NSIS): Framework, R. Hancock, G. Karagiannis et al. , 2005. 17. RFC 2326: Real Time Streaming Protocol (RTSP), H. Schulzrinne et al. , 1998 18. GMPLS tutorial: http: //www. iec. org/online/tutorials/gmpls/ 50 3/18/2018 22. 10. 2007