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Routing Information Protocol 2 (RIP2) Study_Group_208 Shrotri Meghana Dhar Aparna Narkar Priyanka Dulam Vasundhara Mondedula Kalyani Agenda RIP Overview, History and Versions RIP2 over RIP1 Configuring RIP and RIP commands Distance Vector Algorithms and count to infinity problem Protocol Specification and Message Format Addressing Considerations Timers, Input and Output processing Security considerations in RIP2 What is RIPng advantages and usage Disadvantages of RIP2 and proposed solutions Conclusion RIP Overview, History and Versions An interior gateway protocol (IGP), which means that it performs routing within a single autonomous system (Exterior: BGP) The original incarnation of RIP was the Xerox protocol AppleTalk Routing Table Maintenance Protocol (RTMP) and the Banyan VINES Routing Table Protocol (RTP), these are based on the versions of RIP Advantages of RIP and Disadvantages of RIP1 Advantages of RIP: – – – RIP is very useful in a small network, where it has very little overhead in terms of bandwidth used and configuration and management time. Easy to implement than newer IGP’s Many implementations are available in the RIP field. Disadvantages of RIP1: – – – – minimal amount of information for router to route the packet and also very large amount of unused space. Subnet support : Supports subnet routes only within the subnet network Not secure; anyone can act as a router just by sending RIP-1 messages RIP1 was developed for an AS that originally included less than a 100 routers RIP2 Latest version of RIP, RFC: 2453,Build in 1990 Advantages: – An AS can include several hundred routers with RIP-2 protocol. – Compatible upgrade of RIPv1 including subnet routing, authentication, CIDR aggregation, route tags and multicast transmission – Subnet Support : uses more convenient partitioning using variable-length subnets – An end system can run RIP in passive mode to listen for routing information without supplying any. – Low requirement in memory and processing at the node RIP and RIP2 are for the IPv4 network while the RIPng is designed for the IPv6 network. RIP Message Transfer AS 128.10 Network SUB Netted network Routing Table S1 130.10.62.2 S0 130.10.65.1 R IP RI P s Me ge ss sa ag es es M S5 130.10.65.5 Routing Table 128.6 Network SUB Netted network S2 130.10.62.3 S3 130.10.64.3 S4 130.10.64.4 s RIP Message Routing Table 128.8 Network SUB Netted network Practical use in Yahoo Chat IM Routing information protocol: gives command, version ip domain and address information. RIP Configuring and Commands ip routing : enables the router router rip : you can enter configuration commands to define the RIP process for router network network_address : Telling the router which networks it should advertise routes for write, write terminal : Saving configuration & view currently running configuration ping address : To check and see if the packets are getting routed show ip route : To view the routers current routing table show ip rip ? : Gives information about RIP Distance Vector Protocol Compatible upgrade of RIPv1 including subnet routing, authentication, CIDR aggregation, route tags and multicast transmission Subnet support: RIPv1 supports subnet routes only within the subnet network while RIPv2 includes subnet mask in the messages. This allows for subnet knowledge outside subnet. More convenient partitioning using variable length subnet. RIPv2 is a distance vector based routing protocol. RIP2 supports variable-length subnet masks (VLSM). Distance vector routing protocols: Distance-based vector routing protocols base the optimal route on the number of hops (i.e., devices) a packet must pass through to reach a destination. Neighboring nodes send information in regular time intervals Install routes directly in tables, lowest cost wins The information sent (the distance vectors) are all routes from the table The shortest path tree is contained in the routing table Calculations are based on the Bellman-Ford algorithm Potential Problems and Solutions Potential Problems: – Count to infinity problem – Routing loops SOLUTION: Triggered Updates/Split Horizon for Preventing Two-hop Loops Split Horizon: "Split horizon" is a scheme for avoiding problems caused by including routes in updates sent to the router from which they were learned. – Simple - The information about destination routed on the link is omitted – With poisonous reverse -The corresponding distance is set to infinity if the destination is routed on the link Triggered updates: – Split horizon with poisoned reverse will prevent any routing loops that involve only two routers. However, it is possible to end up with patterns in which three routers are engaged in mutual deception. – A timer is associated with each entry in the routing table - much longer than the period of transmission of information – Triggered updates request nodes to send messages as soon as they notice a change in the routing table RIP 2 Packet Format Command -- The command field is used to specify the purpose of the datagram. Version -- The RIP version number. The current version is 2. Protocol Structure - RIP & and RIP2: Routing Information Protocol Max pkt size 512 http://www.colasoft.com/resources/protocol.php?id=RIP2 Address family identifier -- Indicates what type of address is specified in this particular entry. Route tag -- Attribute assigned to a route which must be preserved and readvertised with a route. The route tag provides a method of separating internal RIP routes from external RIP routes, which may have been imported from an EGP or another IGP. IP address -- The destination IP address. Subnet mask -- Value applied to the IP address to yield the non-host portion of the address. If zero, then no subnet mask has been included for this entry. Next hop -- Immediate next hop IP address to which packets to the destination specified by this route entry should be forwarded. Metric -- Represents the total cost of getting a datagram from the host to that destination. RIPv2 Packet Format (With/Without Authentication Header) RIPv2 packet with no Authentication RIPv2 packet with Authentication header Example and Routing Table Structure Included in RIP routing table -Address of (net/subnet/host) destination -Metric associated with destination -Address of next hop router -Recently updated flag -Several timers IP Routing table for Router R1 RIP2 Extensions authentication routing per subnet support of multiple metrics routing domains multicasting Addressing Consideration IP address field in RIP2 message (Request/ Response ) format can be networks, hosts, or a special code used to indicate a default address - example AS 128.10 Network SUB Netted network Routing Table S1 130.10.62.2 ges RIP s Me ge ssa sa Subnet addresses must not be sent outside the network of which the subnet is a part. 0.0.0.0 is used to describe a default route. es S0 130.10.65.1 PM RI – 128.6 Network Address – 128.6.4.1 Host address – 0.0.0.0 Default address S5 130.10.65.5 Routing Table 128.6 Network SUB Netted network S2 130.10.62.3 S3 130.10.64.3 S4 130.10.64.4 RIP Messages Routing Table 128.8 Network SUB Netted network Timers Multiple timers for performance regulation Each route contains the following timers. – Routing-update timer. –--- 30 Seconds Every 30 seconds, the output process is instructed to generate a complete response to every neighboring router/gateway. 30 seconds updates are triggered by a clock not affected system load or service. To prevent collisions – 30 second timer offset by addition of a small random time. Timers – Time out timers. ---- 180 Seconds Set route metric to 16 (Infinity); Route change flag is set The output process is instructed to generate a response message (Notify neighbors). – Garbage collection timer. ----- 120 Seconds Route is deleted from routing table. The output process is instructed to generate a response message (Notify neighbors). Initialization Initialization – – – – This is done when host first comes online. Determine who the neighbors are. Set command field to 1 Send request for entire routing table from neighbors. Operations - Input Processing Handles the datagram received on RIP port (520). Do validation ( such as version number etc) – If validation fails log the error Check command field (Request or Response) Handling Input Request Message– – Initialization Request -- Send entire routing table. – Specific request -- Send only entries requested. – Send response immediately Handling Input Response Message- A response can be received for one of several following reasons. – Response to a specific query (direct UDP connection for the router). – Regular update (Unsolicited response). – Triggered update caused by a route change. RIP Response Message Operations – Output Processing Describes the processing used to create response and request messages. The out put processing is triggered by the following ways. – By input processing – By regular routing update ( broadcast/multi cast at every 30 secs) – By the triggered updates ( When a route changes) Generating Request Message – Can send one Request – Request for entire routing table. Generating Response Messages – Response to Request Sent to only one destination – Regular updates Send the entire routing table – Triggered Updates Create Response messages to neighbors. Interaction between RIPV1 and RIPV2 Limiting Networks Disable Auto-Summarization Single Subnetmask Security Considerations Authentication 1. Plaintext Authentication Algorithm 2.Cryptographic Authentication 1.Keyed Message Digest 5 2.HMAC-SHA1 Peer Security Router Filters RIPng IPv6 compatible version of RIP complete new protocol Uses distance vector algorithm Uses standard port nuber 521 and runs over UDP Installs the best route in the RIPng routing table RIPng v/s RIP-2 RIPng RIP-2 Learns IPv6 route information Learns IPv4 route information Uses port number 521. Uses port number 520 Requires no Requires authentication authentication for RIPng for RIP protocol packets protocol packets. No support for multiple instances of RIPng. Support for multiple instances of RIP-2 RIP2 - Disadvantages RIP-2 supports generic notion of authentication, but only “password” is defined so far. Still not very secure. RIP2 packet size increases as the number of networks increases hence it is not suitable for large networks. RIP2 generates more protocol traffic than OSPF, because it propagates routing information by periodically transmitting the entire routing table to neighbor routers RIP2 may be slow to adjust for link failures. Solution:OSPF within an AS Can support fine-grained metrics (vs. RIP) Multiple metrics – Throughput, Delay, Cost, Reliability Can compute a different routing table for each metric. OSPFv2 supports an extension that allows the metric to be used specified in the packet. Conclusion RIP2 offers many substantial features used to increase the efficiency of RIP1 RIP2 have one negative feature of RIP1 - the path between two subnets is based on the fewest number of router hops RIPng is a complete new protocol designed for Ipv6. It uses the same operations as that of RIP1 and RIP2 References <http://www.pmg.com/otw_nwsl/97_w_rip1.htm> <http://www.javvin.com/protocolRIP.html> <http://www.colasoft.com/resources/protocol.php?id=RIP2> <http://www.protocols.com/pbook/tcpip4.htm> <http://www.soi.wide.ad.jp/soi-asia/pkg1/06/43.html> <http://www.cs.berkeley.edu/~kfall/EE122/lec16/sld010.htm > <http://www.uniar.ukrnet.net/tcpip/crhbook/chap04.html> <http://www.faqs.org/rfcs/rfc2453.html> <http://www.faqs.org/rfcs/rfc1723.html> <http://www.faqs.org/rfcs/rfc1058.html> <http://www.cs.odu.edu/~sudheer/technical/presentations/In troductionToRIP2.pdf> http://www.networkdictionary.com/protocols/rip.php?PHPSES SID=c2a79111d168faf http://www.tcpipguide.com/free/t_RIPOverviewHistoryStanda rdsandVersions.htm http://www.cisco.com/univercd/cc/td/doc/product/software/i os121/121cgcr/ip_c/ipcprt2/1cdrip.htm http://www.duke.edu/~yy7/ee156/rip.htm Questions???
