, Network Management, Future

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1 Tik Computer Networks (3 cr) Spring , Network Management, Future Professor Arto Karila Helsinki University of Technology Tik Computer Networks, , slide 1

2 Electronic Mail Comer 25 Before WWW, electronic mail ( ) was the most widely used and may still be the most useful internet application suits to the sending of short messages as well as long memos and various files can be sent as its attachments differs from the previously discusses internet applications in that it is a "store-and-forward" (rather than "end-to-end") type application This is because the receiving host may not always be on and reachable (just like output to a shared printer) works in a spooled fashion, where outgoing and incoming messages are stored to disk files Figure 25.1 of Comer represents the structure of an system Tik Computer Networks, , slide 2

3 Many proprietary systems can forward from hosts that are not connected to the Internet Among the advantages of Internet are: A uniform service Higher reliability than with gateways End-to-end delivery guarantees that each message remains at the sending host until it is successfully copied to the receiving host gateways often cause problems in practice The ITU-T X.400 Message Handling System (MHS) is almost dead and is largely ignored in this presentation Tik Computer Networks, , slide 3

4 TCP/IP Standards The goal of TCP/IP is interoperability between systems TCP/IP standards are divided into two groups: The first group defines the form of messages The other group defines the exchange of messages between hosts An Internet address is of the form: name> gateways complicate addresses - there is no address standard for messages transferred through a gateway SMTP (Simple Mail Transfer Protocol, RFC 821) is a standard protocol for transferring on top of TCP RFC 822 defines a message format for text messages (ASCII) MIME (Multipurpose Internet Mail Extensions, RFC RFC 2049) defines the encoding of structured objects into Tik Computer Networks, , slide 4

5 The first killer application of the Internet Global addresses of the type: domain_name local_name usually is the name, alias or username of a person but it may also be e.g. a mailing list domain_name defines the mail exchanger, that is the host where the mail for the domain is to be sent For example: < Presidentti@tpk.fi> is the address of the President of Finland can often be sent through which ever SMTP server (increasingly often the servers don t allow relaying) Receiving requires a user account on some host that is always on (the mail exchanger) A common arrangement is a free client program (such as the Qualcom Eudora) on a PC and an account on some Unix host that is always on and permanently connected to the Internet Tik Computer Networks, , slide 5

6 Simple Mail Transfer Protocol (SMTP) MIME standard for the transfer of non-ascii data An example of using from a home PC PC/Eudora SMTP POP-3/IMAP-4 TCP/IP/PPP modems (e.g. V.34) POP server & SMTP server/client E.g. Unix SMTP SMTP server/client E.g. Unix M M PSTN TCP/IP internet Tik Computer Networks, , slide 6

7 An example of (mis)using SMTP The session below send an message using SMTP: telnet mail.cs.hut.fi hutcs.cs.hut.fi 5.65c8/HUTCS-S 1.4 Sendmail is ready at Sun, 25 Feb : 05: HELO Korvatunturi.fi 500 Command unrecognized HELO 963.ip.xgw.fi 250 Hello 963.ip.xgw.fi, pleased to meet you MAIL 250 Sender ok RCPT 250 Recipient ok DATA 354 Enter mail, end with "." on a line by itself Hello Arto, Have you been good? Regards, Santa. 250 Ok Tik Computer Networks, , slide 7

8 ... and the message received X-POP3-Rcpt: From: Date: Sun, 25 Feb :06: To: Hello Arto, Have you been good? Regards, Santa There were at least two things wrong in this example: SMTP is normally not used by hand - the client (e.g. Eudora) runs the protocol without the user ever seeing it Using a wrong sender identity in is unethical - however, it is worth while to know, that forging is quite easy Tik Computer Networks, , slide 8

9 OSI network management ISO has defined: The Common Management Information Protocol (CMIP) The Common Management Information Service (CMIS) CMIP is based on the connection-oriented paradigm This leads into very heavy network management CMIP has not gained popularity in the Internet world The ITU-T recommendation X.700 divides network management into five parts: Fault management Configuration and name management Performance management Accounting management Security management Tik Computer Networks, , slide 9

10 Internet Management (Comer 26) Besides protocols carrying actual payload, systems are needed for locating and fixing problems, controlling routing and finding machines that violate protocol standards Activities such as those mentioned above are referred to as internet management In traditional WANs, management was implemented using low-level (data link layer) control messages In a TCP/IP network there is no uniform data link layer => network management protocols have to be implemented at a higher level The IP routers of the Internet correspond to the switches of a traditional WAN, so they have to be controlled and managed Because an internet consists of different networks, network management protocols are implemented at the application layer on top of generic TCP/IP protocols Tik Computer Networks, , slide 10

11 Internet management Open network management is an essential part of internetworking The network management application on a network management workstation uses a standard management protocol to communicate with the managed devices such as routers The same system can be used to manage e.g.: Switches (e.g. LAN, Frame Relay and ATM switches) Computers and applications Coca-Cola vending machine Anything connected to the network The significance of service and application management is increasing at the same pace as our dependence on critical information systems Tik Computer Networks, , slide 11

12 Simple Network Management Protocol The Simple Network Management Protocol (SNMP) is the standard network management protocol of the Internet The network management application on the network management workstation (client) communicates with the management agents of the managed systems (servers) using SNMP The Management Information Base (MIB) includes configuration parameters of and information collected by the devices The MIB and its elements are defined in the ASN.1 language SNMP messages can be divided into three groups: Get (request/response) asks the value of MIB variable Set (request) sets a variable to the desired value Trap informs about an incident on the device SNMP is run on top of the User Datagram Protocol (UDP) The strength of SNMP is its simplicity (compares with CMIP) The lack of hierarchy in SNMP makes it difficult to manage large networks Tik Computer Networks, , slide 12

13 Management Information Base (MIB) SNMP does not define the management information transferred The MIB standard defines the management information base For example, an IP implementation has to keep count of the octets arrived at each network interface and the network management application can read these values Figure 26.2 shows the classes of MIB variables MIB-2 is an Internet standard on that facilitates vendor and device specific extensions to the MIB The structure of the MIB is defined in the Structure of Management Information (SMI) standard The names and types of MIB variable are defined in the ASN.1 language (Abstract Syntax Notation #1) Tik Computer Networks, , slide 13

14 SNMP v2 SNMP security protocols are defined is RFC-1352 (July, 1992) SNMP v2 is defined and discussed in RFCs 1441 through 1450 and 1452 (April, 1993) SNMP v2 adds e.g. the following to v1: Security MD-5 authentication DES encryption Two new operations Inform for informing other managers about events Get-bulk for retrieving large data blocks Support for several new data types Support for OSI NSAP addresses 64-bit counter data type Unsigned integer data type The same PDU format is used for all SNMP v2 messages Tik Computer Networks, , slide 14

15 SNMP v2 SNMP v2 never really took off e.g. for the following reasons: The new protocol is incompatible with SNMP v1 The security model is not a good one The security mechanisms supported are weak SNMP v2 does not address other important issues of network management, such as scalability SNMPv2 was in practice a failure and is not being used Yet there is a need for a new generation management protocol for the Internet Tik Computer Networks, , slide 15

16 SNMP v3 There is an SNMP Version 3 working group (SNMPv3) in the IETF developing the next generation of SNMP The following objectives are provided to the Working Group: Accommodate the wide range of operational environments with differing management demands Facilitate the need to transition from previous, multiple protocols to SNMPv3 Facilitate the ease of setup and maintenance activities SNMPv3 planned specifications: Modules and Interface Definitions Message Processing and Control Module Specification Security Model Module Specification Local Processing Module Specification Proxy Specification The work is nowhere close to complete, SNMP v1 still reigns Tik Computer Networks, , slide 16

17 RMON Remote Monitor (RMON) is a tool for remotely monitoring the functioning of networks RMON is a standard MIB that defines current and historical MAC-layer statistics and control objects RMON allows the capturing of real-time information across the entire network RMON standard is the SNMP MIB definition described in RFC-1757 (February, 1995) for Ethernet RMON 2 continues the architecture defined in RMON providing a major upgrade and monitoring up to the application level, defined in RFC-2021 (January, 1997) The managed device has an RMON agent that communicates with the network management application via SNMP RMON agent is typically included in LAN switches and routers Tik Computer Networks, , slide 17

18 RMON groups RMON is divided into ten groups, not all of which are supported in all implementations: Ethernet Statistics Group contains statistics measured by the probe for each monitored Ethernet interface History Control Group controls the periodic statistical sampling of data from various types of networks Ethernet History Group records periodic statistical samples from an ethernet network and stores them Tik Computer Networks, , slide 18

19 RMON groups Filter Group allows packets to be matched by a filter equation the matched packets form a data stream that may be captured or may generate events consists of filtertable and channeltable Packet Capture Group allows packets to be captured after they flow through a channel consists of buffercontroltable and capturebuffertable requires the implementation of the filter group Event Group controls the generation and notification of events allows the generation of an SNMP trap, a log entry, or both, for any event consists of the eventtable and the logtable Tik Computer Networks, , slide 19

20 RMON groups Alarm Group periodically takes statistical samples from variables in the probe and compares them to previously configured thresholds If the variable crosses a threshold, an event is generated A hysteresis mechanism is implemented to limit the generation of alarms This group consists of the alarmtable and requires the implementation of the event group Host Group contains statistics associated with each host discovered on the network discovers hosts on the network by listing source and destination MAC Addresses seen in good packets consists of hostcontroltable, hosttable, and hosttimetable Tik Computer Networks, , slide 20

21 RMON groups HostTopN Group ranks hosts according to a statistic type (e.g. the number of errors they generate) and stores the information consists of the hosttopncontroltable and the hosttopntable requires the implementation of the host group Matrix Group stores statistics for conversations between sets of two addresses, as the device detects a new conversation creates a new entry in its tables consists of matrixcontroltable, matrixsdtable and matrixdstable Tik Computer Networks, , slide 21

22 Problems with Internet Management SNMP is not particularly well suited to the management of large networks and not at all well suited to configuring CMIP is too heavy and complex for the Internet Configuring is typically done using vendor-specific tools that still often are TELNET based WWW and Java based network management is gaining popularity WWW functions as the user interface for both configuring and monitoring networks Java 1.1 (or later) makes it possible to use servlets the network management workstation sends servlets (agents) to the managed devices the servlets communicate directly with the management workstation (e.g. using Remote Method Invocation, RMI) The same architecture is suited for service management Tik Computer Networks, , slide 22

23 New Challenges to Network Management Network management is vital to the functioning, configuration, service differentiation, and accounting of large networks Traditional telco networks are over-managed which leads to unnecessary complexity and inefficiency Internets tend to be under-managed We need new solution where the management of core networks and access networks are separated Customer-specific service differentiation and billing are done at the access points, leading to scalability The core network is managed statistically, leading to great efficiency Security of network management is key to the security of the entire network => strong security is needed for network management protocols and applications Tik Computer Networks, , slide 23

24 Internet - the Future B-ISDN? Internet has fulfilled all the promises of OSI and established itself as the leading network technology We are still missing a few things in the Internet, such as: Differentiated quality of service (DiffServ) Security (IPSEC/ISAKMP & PKI) Mobility (Mobile IP) Usage based billing Real multicast capability All of these features are being developed to the Internet Internet technology is developing much faster than traditional networking technology It is a matter of (a short) time before Internet technology will be widely used in public networks carrying voice and video The future of Internet is much more than just IPv6 (Comer) The main obstacles are political - not technical Tik Computer Networks, , slide 24

Simple Network Management Protocol (SNMP)

Announcements Project #5 extended until Dec. 10 Reading: 7.3, start 7.4 Midterm #2 last day to request re-grades Th in class HW#2 (due Tuesday Dec. 7) 1 Simple Network Management Protocol (SNMP) Managed