- 2074 Chaitra · 2+6 marks
Routing criteria; RIP, OSPF, BGP, IGRP, EIGRP
Short answer
Good routing must be correct, robust, stable, fair, adaptive, and efficient. RIP uses hop count (max 15) with 30s updates. OSPF uses Dijkstra with bandwidth cost and areas for fast convergence. BGP is a path-vector protocol for inter-AS routing with policy control. IGRP uses composite metric; EIGRP uses DUAL for fast, loop-free convergence with VLSM support.
Mention the criteria for good routing. Explain RIP, OSPF, BGP, IGRP and EIGRP.
Criteria for good routing
A good routing algorithm should be:
- Correct and simple: it delivers packets to the destination with low overhead.
- Robust: works despite hardware or topology failures.
- Stable: converges to a steady state and avoids loops.
- Fair and optimal: shortest or least-cost path by hop count, delay, bandwidth or cost, and fair to all users.
- Adaptive and scalable: adjusts to traffic and topology change, and works for large networks.
- Efficient: low use of CPU, memory and bandwidth.
Routing protocols
| Protocol | Type | Key points |
|---|---|---|
| RIP | Interior, distance vector | Metric hop count (max 15), updates every 30 s, UDP 520, simple, slow convergence |
| OSPF | Interior, link state | Uses Dijkstra (SPF), cost metric based on bandwidth, areas (area 0 backbone), fast convergence, multicast hello, IP protocol 89 |
| BGP | Exterior, path vector | Between autonomous systems, uses path attributes and policy, runs over TCP 179, backbone of the Internet |
| IGRP | Interior, distance vector (Cisco) | Composite metric of bandwidth, delay, reliability, load; max 255 hops; updates every 90 s; replaced by EIGRP |
| EIGRP | Interior, advanced distance vector (Cisco) | DUAL algorithm, fast convergence, partial triggered updates, composite metric, supports VLSM, loop free, neighbour tables |
Interior vs exterior: RIP, OSPF, IGRP and EIGRP route inside one AS (intra-domain), while BGP routes between ASs (inter-domain).
✓ Answer checked by Claude Opus 5.5 (high effort)
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