Chapter 14 TCP/IP and Routing Part #2 Unix System Administration.
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Transcript of Chapter 14 TCP/IP and Routing Part #2 Unix System Administration.
Chapter 14TCP/IP and Routing Part #2
Unix System Administration
Roto-Routing
There are several routing protocols to meet specific needs RIP - Routing Information Protocol OSPF - Open Shortest Path First IGRP - Interior Gateway Protocol EGP - Exterior Gateway Protocol BGP - Border Gateway Protocol DVMRP - Distance Vector Multicast Routing
Protocol
Let’s All RIP One
RIP is commonly implemented in the routed or gated daemon
RIP uses hop count as its metricRIP is a resource hog due to its
heavy use of broadcastingRIP is good for small networks
without redundant paths or paths of varying bandwidth
Roger, Roger; What’s Your Vector Victor?
OSPF is an industrial strength routing protocol for large, complex networks
OSPF uses distance (hop count) and vector (cost/weight) as its metrics
OSPF handles multiple paths and varying bandwidth links better than RIP
OSPF is more complicated to administrate
IGRP Your EGP
IGRP is a proprietary routing protocol from Cisco system
EGP is an old routing protocol from the ARPANET (pre-Internet)
BGP is the preferred Internet routing protocol
Border Your Gateway
BGP expands on EGPBGP supports an arbitrarily complex
topology of autonomous systems.BGP is typically used if your
company want to use two different Internet Providers
Cheap Routing
ICMP Redirects Use with hosts that don’t understand
routing and only know how to send non-local packets to a smarter device (e.g. router).
If the default router isn’t the correct one, it the forwards packet to the appropriate router and sends back an ICMP redirect to the host for future use.
ICMP Redirect at Work
Let’s Catch A U-Boat With Our Subnet
Subnets is the further breaking down of a network in smaller parts
You subnet the portion of the IP address that is meant for hosts devices (not the part assigned to you)
Subnets let you control traffic and routing policies
The dreaded subnet mask is used to separate the host portion and subnet portion of the IP address
Subnet Mask Example
IP - 159.91.15.220 Mask - 255.255.248.0
Convert to binary and remove the periods
nnnnnnnnnnnnnnnn0000111111011100
nnnnnnnnnnnnnnnn1111100000000000
and together nnnnnnnnnnnnnnnn0000100000000000
separate subnet nnnnnnnnnnnnnnnnssssshhhhhhhhhhh
So IP 159.91.15.220 with subnet mask 255.255.248.0 is in subnet #1 and is host #2012
Subnet Mask Example #2
Assume you have a Class C address, say 192.168.1.0 and you want to create a subnet mask that will allow you to have 6 subnets with up to 26 hosts per subnet. What subnet mask should you use?
Since it is a class C, you only get to work with the last octet which is 8 bits.
How many bits do you need for 6 subnets? How many for 26 hosts?
The subnet mask must be 255.255.255.224
Route This!
Which subnet mask should you select if there are multiple solutions to the # subnets/hosts required?
What would you need to do if you can’t satisfy the number of subnet and hosts per subnet with your IP address class?