Sunday,
January 26, 2020
OSI Model
7. Application Layer
Provides
Services to lower layers. Enables program to program communication and determines
if sufficient resources exist for communication. Examples are e-mail gateways
(SMTP), TFTP, FTP and SNMP.
6. Presentation Layer
Presents
information to the Application layer. Compression, data conversion, encryption and
standard formatting occur here. Contains data formats JPEG, MPEG, MIDI, TIFF.
5. Session Layer
Establishes
and maintains communication ‘sessions’ between applications (dialogue control).
Sessions can be simplex (one direction only), half-duplex (one direction at a time)
or full duplex (both ways simultaneously). Session layer keeps different applications
data separate from other applications. Protocols include NFS, SQL, X Window,
RPC, ASP, and NetBios Names.
4. Transport Layer
Responsible
for end to end integrity of data transmissions and establishes a logical connection
between sending and receiving hosts via ‘virtual circuits’. Windowing works at
this level to control how much information is transferred before
acknowledgement is required.
Data is segmented and reassembled at this layer. Port numbers are used to keep
track of different conversations crossing the network at the same time.
Supports
TCP.
UDP, SPX, NBP, Segmentation works here (Segments) and error correction (not detection).
3. Network Layer
Routes
data from one node to another and determines the best path to take. Routers operate
at this level. Network addresses are used here which are used for routing (Packets).
Routing tables, subnetting and control of network congestion occur here.
Routing
protocols regardless of which protocol the run over reside here. RIP, IP, IPX,ARP,
IGRP, Appletalk.
2. Data Link Layer
Sometimes
referred to as the LAN layer. Responsible for the physical transmission of data
from one node to another. Error detection occurs here. Packets are translated
into frames
here and hardware address is added. Bridges and switches operate at this layer.
Logical
Link Control sub layer (LLC) 802.2 :- manages communications between devices over
a single link on a network. Uses Service Access Points (SAPs) to help lower
layers talk
to the Network Layer.
Media
Access Control (MAC) 802.3 :- builds frames from the 1’s and 0’s that the Physical
Layer (address = 6-byte/48 bit) picks up from the wire as a digital signal and runs
a Cyclic Redundancy Check (CRC) to assure no bits were lost or corrupted.
1. Physical Layer
Puts
data onto the wire and takes it off, physical layer specifications such as the connectors,
voltage, physical data rates and DTE/DCE interfaces. Some common implementations
include Ethernet/IEEE 802.3, Fast Ethernet, and Token Ring/IEEE 802.5.
Cisco Hierarchical Model
Core
Layer – purpose is to switch traffic as quickly as possible. Fast transport to enterprise
services (internet etc). No packet manipulation, VLANs, access-lists. High speed
access required such as FDDI, ATM.
Distribution
Layer – time sensitive manipulation such as routing, filtering and wan access.
Broadcast/Multicast, media translations, security. Access
Layer – switches and routers, segmentation occurs here and workgroup access. Static
(not dynamic) routing.
TCP/IP
Port
Numbers
These
are used to connect to various services and applications and piggy back onto IP addresses.
Common port numbers are:
20
- File Transfer Protocol – Data (TCP)
21
- File Transfer Protocol – Control (TCP) (Listens on this port)
22
- SSH (TCP)
23
- Telnet (TCP)
25
- Simple Mail Transfer Protocol (TCP)
53
- Domain Name Service (TCP/UDP)
69
- Trivial File Transfer Protocol (UDP)
80
- HTTP/WWW (TCP)
110
- Post Office Protocol 3 (TCP)
119
- Network News Transfer Protocol (TCP)
123
- Network Time Protocol (UDP)
161/162
- Simple Network Management Protocol (UDP)
443
- HTTP over Secure Sockets Layer (TCP)
TCP
– (protocol 6) reliable, sequenced connection-oriented delivery, 20-byte
header.
UDP
– (protocol 17) connectionless, unsequenced best effort delivery, 8-byte
header. Sends
data but does not check to see if it is received.
Telnet
– used to connect to a remote device (TCP). A password and username is required to
connect. Telnet tests all seven layers of the OSI model.
FTP
– connection orientated (TCP) protocol used to transfer large files.
TFTP
– connectionless (UDP) protocol used for file transfer.
SNMP
– allows remote management of network devices.
ICMP
– supports packets containing error, control and informational messages.
Ping uses
ICMP to test network connectivity.
ARP
– used to map an IP address to a physical (MAC) address. A host wishing to
obtain a physical address broadcasts an ARP request onto the TCP/IP network.
The host replies with its physical address.
DNS
– resolves hostnames to IP addresses (not the other way around).
To
configure the router to use a host on the network use the command
ROUTER(config)#ip
nameserver 4.2.2.2 and to configure DNS the command
ip
name-server is usually already turned on for the router config by default.
If you want hosts on the network to use the router as a proxy DNS server put
the command ROUTER(config)#ip dnsserver onto the router.
DHCP
– involves a central server or devices which relays TCP information to hosts on
a network.
You can configure a router to be a DHCP server with the below config. You must
have hosts on the same LAN as the router interface:
Router(config)#ip dhcp pool E00_DHCP_Pool
Router(dhcp-config)#network 10.10.10.0 255.255.255.0
Router(dhcp-config)#dns-server 24.196.64.39
24.196.64.40
Router(dhcp-config)#domain-name mydomain.com
Router(dhcp-config)#default-router 10.10.10.254
Router(dhcp-config)#lease 1
Cisco IOS
Six
modes
User
EXEC:- Router>
Privileged
EXEC:- Router#
Global
Configuration:- Router(config)#
ROM
Monitor:- > or rommon>
Setup:-
series of questions
RXBoot:- Router
Editing
Commands
Ctrl+W
- Erases a word
Ctrl+U
- Erases a line
Ctrl+A
- Moves cursor to beginning of line
Ctrl+E
- Moves cursor to end of line
Ctrl+F
- (or right arrow) – Move forward one character
Ctrl+B
- (or left arrow) – Move back one character
Ctrl+P
- (or up arrow) – Recalls previous commands from buffer
Ctrl+N
- (or down arrow) – Return to more recent commands in buffer
Esc+B
- Move back one word
Esc+F
- Move forward one word
Tab
- completes a command you have started
Router# copy ru _ press tab key after the ‘u’
Router# copy running-configuration
?
gives you the command options
Router#copy ?
flash: Copy from flash: file system
ftp: Copy from ftp: file system
nvram: Copy from nvram: file system
running-config Copy from current system configuration
startup-config Copy from startup configuration
system: Copy from system: file system
tftp: Copy from tftp: file system (truncated
to save space)
or
the commands beginning with the letters you have typed:
Router#a?
access-enable access-profile access-template
Router Elements
DRAM
– working area for router. Contains routing tables, ARP cache, packet buffers, IOS
and running config. Some routers run the IOS from DRAM.
show version – shows information about
IOS in RAM and displays how much physical memory
is installed. Also shows the config register setting.
show process – shows info about programs
running in DRAM.
show running-configuration – shows active
configuration in DRAM.
show memory/stacks/buffers – to view
tables and buffers
NVRAM
– stores routers start up configuration. Does not lose data when powered off due
to a battery power source.
show startup-configuration
erase startup-configuration
copy running-configuration
startup-configuration (copy run
start)
Config
register 0x2142 skips start up config file in NVRAM (for password recovery)
Config
register 0x2102 loads start up config files from NVRAM
Flash
– (EEPROM or PCMCIA card) holds the compressed operating system image (IOS).
This is where software upgrades are stored.
show flash
dir flash:
ROM
– contains power on diagnostics, a bootstrap program and a mini IOS (rommon). You
can specify which file the routers boots from if you have more than one in
flash memory.
Router(config)#boot system flash {IOS
filename}
Or
that it boots from a TFTP server if for example the image is too large to fit
in flash.
Router(config)#boot system tftp {IOS filename}{tftp
address)
You
can also back up the flash image for emergency use.
Router(config)#copy flash tftp
Router Management
Console
port: a PC connected to the console port via a rollover cable. Used for initial
configuration
or disaster recovery.
Virtual
Terminals: normally accessed by telnetting to the router. Five lines available
numbered
0-4
Auxiliary
port: normally a modem connected to this port.
TFTP
server: the router can get its configs or IOS from a server (PC for example)
running
TFTP software and holding the necessary files.
NMS:
network management station. Uses SNMP to manage the router normally via a
web
style interface.
CDP
Cisco
Discovery Protocol runs only on Cisco devices (proprietary), it allows you to
gather
information about other routers and switches. It is enabled by default.
Router#show cdp neighbors (note: Cisco uses US spelling conventions)
This
command displays the neighbouring router or switches hostname, hardware
platform,
port identifier and capabilities list.
Router#show cdp neighbors detail
This
command displays more detail than the previous one. You can view IP address,
IOS
release
and duplex setting.
To
turn CDP off an interface use the command:
Router(config-if)#no cdp enable
To
turn CDP off on your entire router or switch use the command:
Router(config)#no cdp run
LAN Switching
A
LAN switch has three primary functions:
1.
Address Learning – maintains a table (CAM – Content Addressable Memory) table
of
addresses
and which port they can be reached on.
2.
Forward/filter decision – forwards frames only out of the relevant port.
3.
Loop avoidance - STP
Broadcast
frames are forwarded out of all ports. Because ethernet hosts can all transmit
at
the same time this can lead to collisions thus slowing down the network
considerably.
Transmitting
Frames Through a Switch
Store-and-Forward
– switch copies the entire frame into its buffer and computes the
CRC.
Frame is discarded if there is an error. High latency.
Cut-through
– reads only the destination address (first 6 bytes after preamble), looks up
address
and forwards frame. Lower latency.
Fragment
free – switch reads first 64 bytes before forwarding the frame. Collisions
normally
occur within the first 64 bytes.
Spanning Tree Protocol (STP) IEEE 802.1d
STP
is a link management protocol that provides path redundancy whilst preventing
undesirable
loops in the network. For communication to work correctly on an ethernet
network
there can only be one path between two destinations. STP uses Bridge Protocol
Data
Units (BPDU) received by all switches to determine the spanning-tree topology.
A
port
on a switch is either in forwarding or blocking state. Forwarding ports provide
the
lowest
cost path to the root bridge, a port will remain in blocking state from start
up if
spanning
tree determines there is a better path.
Rapid Spanning Tree Protocol (RSTP) IEEE 802.1w
Spanning
tree takes up to 50 seconds to converge to a stable network whereas RSTP takes
2 seconds. RSTP port roles are root port, designated port, backup port,
alternate port and disabled. Most implementations of RSTP use PVST+, Per VLAN
Spanning Tree+, here multiple instances of Spanning Tree are running so the
load on the CPU is higher but we can load share over the links.
To
enable RSTP for each VLAN in our switched network we use the following
command:
Switch(config)#spanning-tree
mode rapid-pvst
Bridging
/ Switching
Bridges
are primarily software based and have one spanning-tree instance per bridge.
Normally
16 ports per bridge. LAN Switches are primarily hardware based. Many
spanning-tree
instances per switch and up to 100 ports.
Virtual LAN (VLAN)
A
VLAN is a switched network that consists of logically segmented communities
without
regard
to physical location. Each port on a switch can belong to a VLAN. VLAN ports
share
broadcasts. A router is needed to route traffic between VLANs because layer 2
devices
do not use IP addresses. Reduces admin costs, tighter security and better
control of broadcasts
Subnetting
Max
# of Subnets = 2(to the power of masked bits) (– 2 if subnet zero not allowed)
Max
# of Hosts (per subnet) = 2(to the power of unmasked bits) – 2
Easy
Subnetting
What
network is host 172.16.5.68 255.255.255.240 on?
256-240
= 16 so you have the subnets going up in increments of 16 starting with zero
(if
subnet
zero is permitted in the exam). Each subnet will need to have a subnet and a
broadcast
number so this leaves 14 hosts per subnet. The subnets start at 0,16,32,48, 64,
80….224,
240 (the 0 and 240 are only valid if subnet zero is allowed).
IPV6
An
IPv6 address consist of 128 bits represented in hexadecimal format separated
into
eight
parts e.g. EEDE:AC89:4323:5445:FE32:BB78:7856:2022.
There
are no broadcast packets, only anycast – multicast – unicast.
The
two methods of migrating from IPv4 to IPv6 are dual stack and tunneling.
Cisco
IOS support IPv6 commands in version 12.2(2)T and later.
IP Routing
Routers
must have some means of learning networks that are not directly connected.
Static
routing:
Router(config)#ip route {destination
network}{mask}{next hop address}
e.g ip route 172.16.5.2 255.255.255.0 172.16.12.8
Dynamic
addressing is done by using a routing protocol:
for
RIP v2
Router(config)#router rip
Router(config-router)#version 2
Router(config-router)#network 172.16.0.0
Router(config-router)#no auto-summary _ optional
for
EIGRP
Router(config)# router eigrp 20
Router(config-router)#network 172.16.0.0
Router(config-router)#no auto-summary _ optional
for
OSPF
Router(config)#router ospf 20
Router(config-router)#network 172.16.0.0 0.0.255.255
area 0
Facts
RIP v2
Uses
UDP port 520
Classless
Max
hop count 15
Multicasts
route updates to 224.0.0.9
Supports
authentication
Update
timer 30 seconds
Invalid
90 seconds
Hold
down 180 seconds
Flush
270 seconds
EIGRP
Uses
IP protocol 88
Classless
Hybrid
of distance vector and link state
Multicasts
updates to 224.0.0.10
Uses
feasible successors to determine alternative routes to networks.
The
feasible successor is a backup route based upon the topology table.
OSPF
Uses
IP protocol 89
Classless
Uses
Dijkstras shortest path algorithm (SFP)
Router
ID is the highest IP address but loopback address used if present
Backbone
area is area 0
All
non backbone areas must connect directly to area 0
Areas
can be numbered from 0 to 65535
Multicasts
on 224.0.0.5
OSPF
uses cost as a metric (see below - * indicates the most common)
Interface Cost (108/Bandwidth)
ATM,
Fast Ethernet, Gigabit Ethernet, FDDI (> 100 Mbps) 1
HSSI
(45Mbps)
2
16
Mbps Token Ring
6
10
Mbps Ethernet
10
4
Mbps Token Ring
25
T1
(1.544 Mbps)*
64
DS-0
(64k)*
1562
56k
1785
Distance Vector
Distance
Vector protocols understand the direction and distance to any given network
connections.
Algorithms calculate the cost to reach the connection and pass this
information
to every neighbour router. Examples are RIP and IGRP. Problems with
distance
vector protocols include routing loops and counting to infinity.
To
overcome these problems the following can be implemented:
Defining
a maximum number of hops, 15 for RIP and 255 for IGRP
Split
Horizon – if the router learns a route on an interface do not advertise it out
of the
same
interface.
Route
Poisoning – Information passed out of an interface is marked as unreachable by
setting
the hop count to 16 (for RIP).
Hold
Down Timers – ignores new routing updates until a determined time has passed.
Triggered
Updates – instead of routing updates being sent at the default intervals; a
triggered
update is sent every time to indicate a change in the routing table.
Link State
These
have a picture of the entire network from link state advertisements (LSA) and
link
state
packets (LSP). Once these have all been passed only changes to the network are
sent
out reducing network traffic.
Link
state protocols do require a lot of CPU time and bandwidth when LSAs are
flooded
out.
Examples are OSPF and ISIS.
Routers
use administrative distances to determine how believable the route learned is
depending
upon the protocol it learns the router from.
Source Default Distance
Directly
Connected Interface 0
Static
hop to next router
1
EIGRP
Summary
5
External
BGP
20
EIGRP
(Internal)
90
OSPF
110
IS-IS
115
RIP
120
Exterior
Gateway Protocol (EGP) 140
External
EIGRP
170
Internal
BGP
200
Unknown
255
An
administrative distance of 0 is most preferred. So a router running RIP and
OSPF will prefer the OSPF routes most and install these in the routing table.
Routing
protocols maintain a table of hosts and which interface they can be reached by.
Examples
RIP, OSPF
BGP
is an exterior gateway protocol. It is used to connect autonomous systems
together.
Routed
protocols are used to transport traffic from source to destination. Examples:
IP,
IPX,
Appletalk.
When
a packet traverses the network from device to device (hop to hop) the IP
address
remains
constant, the hardware (MAC) address changes.
NAT
Network
Address Translation will convert and address from the inside of your network to
another
address on the outside of your network and vice versa. It is most commonly used
to convert a non-routable address to a routable address.
For
all configs, you must specify which interfaces are internal for NAT and which
are
external:
R
outer(config-if)#ip nat inside/outside
Static
NAT – maps one address to one address such as 192.168.1.1 to 200.1.1.1
Router(config)#ip nat inside source static
192.168.1.1 200.1.1.1
Dynamic
NAT – maps a number of internal addresses to a pool of external addresses. The
below config creates a pool of 10 addresses with a mask (prefix length) of
255.255.255.0
and
the name ‘ad_team.’ The hosts to be NATted are on the 192.168.1.0 network. The
access
list (source list) tells the router which addresses to NAT.
Router(config)#ip nat pool ad_team 10.0.0.1 10.0.0.10
prefix-length 24
Router(config)#ip nat inside source list 1 pool
ad_team out
Router(config)#access-list 1 permit 192.168.1.0
0.0.0.255
Overload
NAT – (or PAT) maps private internal addresses to one or more external
addresses
using port numbers. The below config creates a pool of ten addresses (it could
be more) and the command ‘overload’ tells the router to use port address
translation.
Router(config)#ip nat pool ad_team 10.0.0.1 10.0.0.10
prefix-length 24
Router(config)#ip nat inside source list 1 pool
ad_team out overload
Router(config)#access-list 1 permit 192.168.1.0
0.0.0.255
Wireless Networking
Wireless
Basics
Wireless
clients connect to access points. The two wireless modes are ad-hoc and
infrastructure.
Ad hoc is similar to peer-to-peer networking where nodes connect directly
to
each other. They must have the same SSID and channel for this to work. In
infrastructure
mode the clients connect to the access point. They can be via basic service set
(BSS – 1 access point and multiple clients) or extended service set (ESS – 2 or
more BSS’).
Wireless Security
The
two methods for wireless authentication are open system and shared key. In open
system
the host sends an association request to the wireless access point and it will
be
sent
a success or failure message. With shared key, a key or pass phrase is
configured on both the host and access point.
There
are three types of shared key authentication WEP,
WPA
and WPA2.
WEP
is an encryption algorithm built in the 802.11 standard. It uses RC4 40bit or
104 bit
keys
and a 24bit initialization vector.
WPA
uses dynamic key management, adds a stronger encryption cipher and is built on
the
EAP/802.1X mechanism. It uses TKIP, Temporal Key Integrity Protocol and the
Initialization
Vector is increased to 48bit (more then 500 trillion key combinations). It is
used
with RADIUS in the enterprise.
WPA2
is the next generation in wireless security. It uses even stronger encryption
than
WPA
and this is achieved by using AES, Advanced Encryption Standard. Also WPA2
creates
a new key for every new association this has a benefit over WPA that the
client's
keys
are unique and specific to that client.
Network Security
Access
Lists
Access
lists are a set of conditions that permit or deny access to or through a
routers
interface.
Range
Usage
1-99 IP
Standard
1300-1999
IP Standard (Expanded Range)
100-199
IP Extended
2000-2699
IP Extended (Expanded Range)
Standard Access Lists
Standard
IP access lists check only the source address of the packet and permits or
denies
the
entire TCP/IP suite. You cannot choose a particular port or application to
block.
Cisco
recommends that they are placed as close to the destination as possible.
Router(config)#access-list{number
1-99}{permit/deny}{source address}
access-list 10 permit 172.16.5.2 _ address can be a host or network
Extended Access Lists
These
allow for a lot more granularity when filtering IP traffic. They can filter
packets
based
upon source or destination, a particular IP protocol and port number. Cisco
recommends
that they are placed as close to the source as possible.
Router(config)#access-list {number
100-99}{permit/deny}{protocol}
{source}{destination}{port}
access-list 112 permit tcp host 172.16.5.2 host
172.16.10.2 eq www
Named Access Lists
Router(config)#ip access-list {standard/extended}
name
Router(config)#ip access-list extended no_ftp
Access
lists applied to inbound interfaces save the router having to process the
packet,
denied
packets will be dropped at the interface. Outbound access lists will be
processed
by
the router and then dropped at the outbound interface if they match the access
list.
Access
lists can be applied to multiple interfaces but there can only be one access
list per
protocol
per direction per interface.
Wildcard
masks tell the router which parts of the address to look at and which to
disregard.
access-list 12 permit 172.16.5.0 0.0.0.255
This
would permit any host on network 172.16.5.x
Access
lists are applied to interfaces:
Router(config)#access-list 1 permit 172.16.5.2
Router(config)#interface e0
Router(config-if)#ip access-group 1 in
Use
the term ‘access-class’ if applying to console/aux/vty lines
show ip access-lists
show access-list 1
Packets
are processed by the access list and then routed.
Passwords
(command ‘service password-encryption’
encrypts all passwords)
Enable:
used to get from user exec to privileged exec. Not encrypted.
Router(config)#
enable password {password}
Enable
Secret: Encrypts password (only use enable or enable secret not both)
Router(config)# enable secret {password}
VTY:
needed if telnet access is required.
Router(config)#line vty 0 4
Router(config-line)#password cisco
Router(config-line)#login
Auxiliary:
allows modem access to the aux port.
Router(config)#line aux 0
Router(config-line)#password cisco
Router(config-line)#login
Console:
used to allow console access
Router(config)#line console 0
Router(config-line)#password cisco
Router(config-line)#login
Protecting the Network
Firewalls
divide your network into three zones – trusted, semi-trusted and un-trusted.
A
VPN allows information to be send securely over an insecure medium (e.g. the
internet).
A VPN can be site to site (e.g. WAN) or access (e.g. home worker).
Security
Device Manager (SDM)
SDM
is a GUI web based tool which will allow you to configure and manage your Cisco
routers.
It can be installed on your router or your PC. To install and configure SDM you
a
huge amount of parameters and screens to navigate.
Wan Protocols and Services
HDLC
– Cisco default on serial WAN connections. No authentication available.
PPP
– data link. Uses PAP (clear text) and CHAP (secure hash) authentication.
Authentication
is optional. Use PPP if connecting a Cisco router to a non-cisco router.
Router(config)#hostname paul password cisco _ case sensitive
Router(config)#interface serial 0
Router(config-if)#encapsulation ppp
Router(config-if)# ppp authentication chap
Frame Relay
Based
upon x.25 protocol but with less error checking so is quicker. Normally 56k to
2mb
so ideal for SMEs. Works at the physical & data link layers. DLCI’s are
used to
identify
the circuit. Each router uses LMIs for keepalives on the line between the
router
and
frame relay switch. LMI type is Cisco by default. You must use another type
such
as
ansi if connecting to a non-cisco router.
Router(config-if)#encapsulation frame-relay
Router(config-if)#frame-relay map ip 2.2.2.2 100
Here
the router is told to get to ip address 2.2.2.2 use dlci 100.
Frame
Relay Problems include:
Incorrect
LMI setting
Incorrect
DCLI
Split
horizon preventing routing updates leaving interface
Use
frame relay sub-interfaces if point-to-point or multipoint connection is
needed. IP
address
applied to sub-interfaces for these and NOT the main interface.
Frame
relay uses backwards explicit congestion notification (BECN) on returning
frames
to
warn of congestion and forward explicit congestion notification (FECN) is set
by the
DCE
end to warn of congestion from the sending end.
Troubleshooting
Always
use a systematic and methodical approach to troubleshooting.
The
first command to issue is ‘show ip interface
brief’ to establish if the interfaces
are
down or up. There are only a handful of ways to break any network in the exam.
Layer
1
Ensure
that there is a clock rate on the DCE interface (use the ‘show controllers
serial X’ command to check what type of cable
is attached – where X is the serial
interface
number).
Ensure
that the ‘no shut’ command has been applied to the interface.
Layer
2
Ensure
that the correct encapsulation type is on the interface i.e. HDLC, PPP etc (use
the
‘show interface serial X’ command to check).
If
it is not then go into interface configuration mode and change it.
Layer
3
Ensure
that the correct IP address AND subnet mask is applied to the interface.
Ensure
that the correct networks are being advertised by the routing protocol
(‘show ip
protocols’).
Always
ensure that you can ping across directly connected router interfaces BEFORE
applying
routing protocols and access lists. You have been warned.
Characteristic
|
OSPF
|
RIPv2
|
RIPv1
|
Type
of protocol
|
Link
state
|
Distance
vector
|
Distance
vector
|
Classless
support
|
Yes
|
Yes
|
No
|
VLSM
support
|
Yes
|
Yes
|
No
|
Auto-summarization
|
No
|
Yes
|
Yes
|
Manual
summarization
|
Yes
|
No
|
No
|
Discontiguous
support
|
Yes
|
Yes
|
No
|
Route
propagation
|
Multicast
on change
|
Periodic
multicast
|
Periodic
broadcast
|
Path
metric
|
Bandwidth
|
Hops
|
Hops
|
Hop
count limit
|
None
|
15
|
15
|
Convergence
|
Fast
|
Slow
|
Slow
|
Peer
authentication
|
Yes
|
Yes
|
No
|
Hierarchical
network
|
Yes
(using areas)
|
No
(flat only)
|
No
(flat only)
|
Updates
|
Event
triggered
|
Route
table updates
|
Route
table updates
|
Route
computation
|
Dijkstra
|
Bellman-Ford
|
Bellman-Ford
|
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