Routing Protocols
1. Interior (within an autonomous system
a. Distance Vector - understands the direction and distance to any network connection on the internetwork. Knows how may hops (metrics) to get to that destination. Possible problems include: slow convergence, routing loops, counting to infinity (solved my max hop count). Solutions include: split horizon (cant send back where it came from); hold-down timers (prevent regular updates messages from recreating in tables that it is up); hop count ; Uses seconds hand info
1. RIP - routing information protocol - 15 hop count maximum
30 seconds update
Route invalid timer 90 seconds
metrics
2. IGRP - Interior gateway routing protocol (CISCO) - 255 hop count maximum, reliability factor (255) and bandwidth delay measured in 10 MS. Implements hold downs, split horizons, and poison reverse updates; 90 seconds
b. Link State - understands the entire network and does not use secondhand information. routers exchange LSP (Link state protocols - hi packets) Each router builds a topographical view then uses SPF (shortest path first) to determine he best route. Convergence is fast. Bandwidth is the measurement
1. OSPF (open shortest path first) - decisions based on cost of route (metric limit of 65,535) - used in he TCP/IP stack
2. NLSP - Novell’s Link State Protocol
c. Hybrid
EIGRP - (enhanced Interior gateway protocol) combined link state and distance vector - distance vectors triggered by change, not timers; Faster convergence, multiprotocol support
2. Exterior
a. EGP (exterior gateway protocol)
Polls Neighbors
exchanges info about AS with neighbors
very simple
b. BGP (border gateway protocol (CISCO)
can detect routing loops
can work between AS
3. Other Random protocols
CDP - Cisco Discovery Protocol60 second updates
Runs SNAP - Subnetwork Access Protocol at the datalink layer
routers running different protocols to communicate
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Aleeya dotNet Tags: Interior Routing Protocols autonomous Distance Vector connection network metrics destination problems convergence split infinity internetwork hops metrics split horizon hold-down timers prevent updates messages hop RIP count protocol reliability poison reverse updates Link State LSP packets topographical SPF shortest path first Convergence Bandwidth OSPF EIGRP multiprotocol EGP BGP CDP SNAP Filed under: Networking (Technorati) .
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This entry was posted on Friday, August 26th, 2005 at 1:31 pm
You can also choose to read Token Ring Basics, which is the previous entry, or PPP Info, the next entry.
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