Advanced Ip Read And Learn

Front 1

Variable Length Subnet Masking or VLSM (RFC 1812) can be defined as the capability to apply more than one subnet mask to a given class of addresses throughout a routed system.

Back 1

Classless Routing Protocols:
EIGRP, OSPF, RIPv2, IS-IS and BGP

Classful Routing Protocol:
RIPv1

Front 2

Classful routing protocols (RIPv1) do not include the subnet mask of advertised networks in there routing updates.

Back 2

VLSM has 2 advantages:

Makes network addressing more efficient

Provides the capability to perform route summarization

Front 3

Route Summarization is the shortening of the mask to include several smaller networks into one larger network address.

Back 3

Route summarization takes a set of contiguous networks or subnets and groups them together using a shorter subnet mask.

Front 4

Advantages of summarization
reduces the number of entries in the route table,
reduces load on the router and network overhead,
hides instability in the system behind the summary which remains valid even if summarized networks are unavailable.

Back 4

Summarization rules:
Design the network with summarization in mind.
Summarize into the Core of the network.

Front 5

Supernetting, Aggregation and Summarization are all the same thing.

Back 5

A route summarization begins in the interesting octect (network).
Write the routes out in binary.
Anywhere where the digits are repeated for all routes gets a 1, anywhere where digits are not always repeated gets a zero.

11111111.11110000.00000000.00000000
That can also be expressed as
255.240.0.0 or /12
So, our summary statement becomes
172.16.0.0 255.240.0.0
or
172.16.0.0 /12

Front 6

2nd step of route summarization

Back 6

Administrative Distance:
If a router learns of multiple routes to a given network the routing information source with the lowest administration distance will be chosen and used.

Front 7

Default Administrative Distances:

Connected Interface: 0
Static Route: 1
EIGRP: 90
IGRP: 100
OSPF: 110
IS-IS: 115
RIP: 120

Back 7

A metric is a measurement of how good a particular route is.
The lower the metric, the better the route.

Front 8

4 Criteria for Routing decisions:
1. Administrative Distance
2. Valid Next Hop Address
3. Best Metric
4. Longest Match

Back 8

Valid Next Hop address:
A router cannot install a route in the routing table unless the next-hop address is valid.

Front 9

Longest Match
The longest match refers to the longest prefix length - or the longest matching string of bits in the route as compared to the destination address of the packet being routed.

Back 9

Longest Match:
The longer the match in the prefix, the more detailed the route is.

Front 10

Longest Match:
Longest match to 172.16.10.131:

131 binary is as follows:
10000011
So ONLY a /24 can match.
the correct answer (as opposed to the utter crap in the book) is 172.16.10.0 /24

Back 10

Holy Jesus, IPV6.

Front 11

IPV6 is 128 bits long.
8 sets of 4 hex characters seperated by colons

2201:0FA0:080B:2112:0000:0000:0000:0001

Back 11

Rules for truncating IPv6:
1. Drop leading zeros - Zeros that appear leading in each set:
2201:FA0:80B:2112:0:0:0:1

Front 12

Rules for truncating IPv6:
2. Condense contiguous groups of all-zero sets:
2201:FA0:80B:2112::1
(In other words... between 2112 and 1 we have 3 contiguous sets of 0's. The double colon represents all three sets. You can only do this once.)

Back 12

Rules for truncating IPv6:
3. Mask is done as slash notation of the prefix length.
(exactly like it is done IPv4, except the number could theoretically be as big as /128)

Front 13

Types of IPv6 addresses:
Unicast
Multicast
Anycast

Back 13

IPv6 Unicast:
Just like it's IPv4 counterpart, it is unique to a singular host.

Front 14

IPv6 Multicast:
A single IPv6 multicast address is assigned to mutliple hosts so that a packet sent to the address may be delivered to multiple hosts at the same time. Multicast addresses always start with the prefix FF00::/8.

Back 14

IPv6 Anycast:
A single address that is assigned to multiple hosts. Delivered to the ONE host that is nearest according to the routing protocols idea of distances. No special prefix for anycast address.

Front 15

IPv6 still uses DHCP to assign IP addresses.
A scope of IPv6 addresses is set to hand out. This is called stateful addressing, where the DHCP server keeps track of what hosts have been assigned what IPv6 address.

Back 15

Stateless Autoconfiguration:
Allows a host to choose and configure an address for itself.

Front 16

Static configuration
Static configuration using EUI-64
Dynamic configuration using DHCP to assign 128-bit address
Dynamic configuration using stateless autoconfiguration with EUI-64

Back 16

Static Configuration: The administrator chooses a static IPv6 address to the host NIC.

Front 17

Static configuration using EUI-64:
The administrator manually configures the address with the local /64 network prefix followed by the hosts mac in EUI-64 format.

Back 17

Dynamic configuration using DHCP to assign 128-bit address:
The host is set to obtain its address from DHCP and the DHCP server is set up to hand out IPv6 addresses from a scope.

Front 18

Dynamic configuration using stateless autoconfiguration with EUI-64:
The host is set to obtain its address automatically, but the DHCP server either does not exist or if it does it only informs the host of the /64 local network prefix.

Back 18

IPv6 router configuration:
Interface Fastetherner 1/0
ipv6 address 2001:AB00:00FF:1::/64 eui-64

Front 19

Show ipv6 interface

Back 19

IPv6 features:
IPSec (mandatory)
Mobility
Fixed Header size (at 40 bytes or 320 bits)
ICMP for IPv6 has changed adding new functionality
IPv6 makes extensive use of Router Solicitation (RS) and Router Advertisement (RA) messages - multicast messages to the addresses FF02::1 and FF00::2, respectively. The RS is sent from a host to all routers on the link as a multicast and the RA message is sent from a router to all hosts on the link, also as a multicast. This is one way that the hosts learn whether DHCP is supported on the link and possibly the DHCP server address.