Routing Information Protocol 2 RIP 2 StudyGroup208 Shrotri

Routing Information Protocol 2 (RIP 2) Study_Group_208 Shrotri Meghana Dhar Aparna Narkar Priyanka Dulam Vasundhara Mondedula Kalyani

Agenda u u u RIP Overview, History and Versions RIP 2 over RIP 1 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 RIP 2 What is RIPng advantages and usage Disadvantages of RIP 2 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) u The original incarnation of RIP was the Xerox protocol u Apple. Talk Routing Table Maintenance Protocol (RTMP) and the Banyan VINES Routing Table Protocol (RTP), these are based on the versions of RIP u

Advantages of RIP and Disadvantages of RIP 1 u Advantages of RIP: – – – u 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 RIP 1: – – 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 RIP 1 was developed for an AS that originally included less than a 100 routers

RIP 2 u u u Latest version of RIP, RFC: 2453, Build in 1990 Advantages: – An AS can include several hundred routers with RIP-2 protocol. – Compatible upgrade of RIPv 1 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 RIP 2 are for the IPv 4 network while the RIPng is designed for the IPv 6 network.

RIP Message Transfer

Practical use in Yahoo Chat IM u Routing information protocol: gives command, version ip domain and address information.

RIP Configuring and Commands u u u u ip routing : enables the router rip : you can enter configuration commands to define the RIP process for router 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 u u u Compatible upgrade of RIPv 1 including subnet routing, authentication, CIDR aggregation, route tags and multicast transmission Subnet support: RIPv 1 supports subnet routes only within the subnet network while RIPv 2 includes subnet mask in the messages. This allows for subnet knowledge outside subnet. More convenient partitioning using variable length subnet. RIPv 2 is a distance vector based routing protocol. RIP 2 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. u Neighboring nodes send information in regular time intervals u Install routes directly in tables, lowest cost wins u 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 u Command -- The command field is used to specify the purpose of the datagram. u Version -- The RIP version number. The current version is 2. u Address family identifier -- Indicates what type of address is specified in this particular entry. u 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. u IP address -- The destination IP address. u 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. u Next hop -- Immediate next hop IP address to which packets to the destination specified by this route entry should be forwarded. u Metric -- Represents the total cost of getting a datagram from the host to that destination. Protocol Structure - RIP & and RIP 2: Routing Information Protocol Max pkt size 512 http: //www. colasoft. com/resources/protocol. php? id=RIP 2

RIPv 2 Packet Format (With/Without Authentication Header) u RIPv 2 packet with no Authentication u RIPv 2 packet with Authentication header

Example and Routing Table Structure u 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 R 1

RIP 2 Extensions u authentication u routing per subnet u support of multiple metrics u routing domains u multicasting

Addressing Consideration u IP address field in RIP 2 message (Request/ Response ) format can be networks, hosts, or a special code used to indicate a default address - example – 128. 6 Network Address – 128. 6. 4. 1 Host address – 0. 0 Default address u u Subnet addresses must not be sent outside the network of which the subnet is a part. 0. 0 is used to describe a default route.

Timers u u Multiple timers for performance regulation Each route contains the following timers. – Routing-update timer. –--- 30 Seconds u Every 30 seconds, the output process is instructed to generate a complete response to every neighboring router/gateway. u 30 seconds updates are triggered by a clock not affected system load or service. u To prevent collisions – 30 second timer offset by addition of a small random time.

Timers – Time out timers. ---- 180 Seconds u Set route metric to 16 (Infinity); u Route change flag is set u The output process is instructed to generate a response message (Notify neighbors). – Garbage collection timer. ----- 120 Seconds u Route is deleted from routing table. u The output process is instructed to generate a response message (Notify neighbors).

Initialization u 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 u u u 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 u u Describes the processing used to create response and request messages. The out 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 u Sent to only one destination – Regular updates u Send the entire routing table – Triggered Updates u Create Response messages to neighbors.

Interaction between RIPV 1 and RIPV 2 u Limiting Networks u Disable Auto-Summarization u Single Subnetmask

Security Considerations u Authentication 1. Plaintext Authentication Algorithm 2. Cryptographic Authentication 1. Keyed Message Digest 5 2. HMAC-SHA 1 u Peer Security u Router Filters

RIPng u u u IPv 6 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 IPv 6 route information Learns IPv 4 route information Uses port number 521. Uses port number 520 Requires no authentication Requires authentication for RIPng protocol packets. RIP protocol packets No support for multiple instances of RIPng. Support for multiple instances of RIP-2

RIP 2 - Disadvantages u u RIP-2 supports generic notion of authentication, but only “password” is defined so far. Still not very secure. RIP 2 packet size increases as the number of networks increases hence it is not suitable for large networks. RIP 2 generates more protocol traffic than OSPF, because it propagates routing information by periodically transmitting the entire routing table to neighbor routers RIP 2 may be slow to adjust for link failures.

Solution: OSPF within an AS Can support fine-grained metrics (vs. RIP) u Multiple metrics u – Throughput, Delay, Cost, Reliability Can compute a different routing table for each metric. u OSPFv 2 supports an extension that allows the metric to be used specified in the packet. u

Conclusion RIP 2 offers many substantial features used to increase the efficiency of RIP 1 u RIP 2 have one negative feature of RIP 1 - the path between two subnets is based on the fewest number of router hops u RIPng is a complete new protocol designed for Ipv 6. It uses the same operations as that of RIP 1 and RIP 2 u

References u u u u <http: //www. pmg. com/otw_nwsl/97_w_rip 1. htm> <http: //www. javvin. com/protocol. RIP. html> <http: //www. colasoft. com/resources/protocol. php? id=RIP 2> <http: //www. protocols. com/pbook/tcpip 4. htm> <http: //www. soi. wide. ad. jp/soi-asia/pkg 1/06/43. html> <http: //www. cs. berkeley. edu/~kfall/EE 122/lec 16/sld 010. htm > <http: //www. uniar. ukrnet. net/tcpip/crhbook/chap 04. html> <http: //www. faqs. org/rfcs/rfc 2453. html> <http: //www. faqs. org/rfcs/rfc 1723. html> <http: //www. faqs. org/rfcs/rfc 1058. html> <http: //www. cs. odu. edu/~sudheer/technical/presentations/In troduction. To. RIP 2. pdf> http: //www. networkdictionary. com/protocols/rip. php? PHPSES SID=c 2 a 79111 d 168 faf http: //www. tcpipguide. com/free/t_RIPOverview. History. Standa rdsand. Versions. htm http: //www. cisco. com/univercd/cc/td/doc/product/software/i os 121/121 cgcr/ip_c/ipcprt 2/1 cdrip. htm http: //www. duke. edu/~yy 7/ee 156/rip. htm

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