Cisco Ios Interior Routing Protocols printable pdf download

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Unicast Routing Protocols Comparison

Router Roles

Metric Formula

OSPF Configuration

OSPF

RIP

EIGRP

OSPF

IS-IS

BGP

Internal Router

reference-bandwidth

! Create an OSPF process

cost =

All interfaces reside within the same area

Type

Distance Vector

Link State

Path Vector

OSPFv2 Link State Advertisements

link speed

[ipv6] router ospf process-ID

Backbone Router

Router Link (Type 1)

Algorithm

Bellman-Ford

DUAL

Dijkstra

Path Selection

Adjacency States

A router with at least one interface in area 0

! Specify a router ID formatted as IPv4 dotted-decimal

Lists neighboring routers and the cost to each;

Down

ExStart

router-id router-ID

Area Border Router (ABR)

Admin Distance

120

90/170 (external)/5 (summary)

110

115

20/200 (IBGP)

flooded within an area

Connects two or more areas

Attempt

Exchange

! Modify the default reference bandwidth

Standard

RFCs 2080, 2453

Cisco proprietary

RFCs 2328, 5340

ISO 10589, RFC 1142

RFC 4271

Network Link (Type 2)

AS Boundary Router (ASBR)

Init

auto-cost reference-bandwidth speed-in-mbps

Generated by a DR; lists all routers on an

Supported Protocols

IPv4, IPv6

IPv4, IPv6, IPX, Appletalk

IPv4, IPv6

IPv4, IPv6, CLNP

IPv4, IPv6

Connects to additional routing domains

adjacent segment; flooded within an area

2-Way

Full

! Assign interfaces to areas by network (OSPFv2)

(redistribution to or from other protocols)

Transport

UDP/520

IP/88

IP/89

Layer 2

TCP/179

Network Summary (Type 3)

network IPv4-address wildcard-mask area area

Message Types

Generated by an ABR; advertises routes

Area Types

Authentication Plain, MD5

MD5

Plain, MD5, AH (v3)

Plain, MD5

MD5

! Identify neighbors for NBMA links (OSPFv2)

between areas

Hello

LS Update

Standard Area

neighbor IPv4-address [cost 1-65535]

Multicast Address 224.0.0.9

224.0.0.10

224.0.0.5-6

N/A

ASBR Summary (Type 4)

Default OSPF area type

DB Descr.

LS Ack

Injected by an ABR into the backbone to

! Configure summaries on area border routers

Stub Area

LS Request

advertise the presence of an ASBR in a non-

area area range { IPv4-address subnet-mask | IPv6-prefix }

Terminology

RIP Configuration

RIP

External link (type 5) LSAs are replaced with

backbone area

a single default route

Split-Horizon

DR/BDR Election

! Summarize external routes (ASBRs only)

! Enable RIPv2 IPv4 routing

External Link (Type 5)

Mitigates routing loops by ensuring a

Totally Stubby Area

summary-address IPv4-address subnet-mask [not-advertise]

The DR serves as a common

RIP Implementations

router rip

Generated by an ASBR and flooded throughout

route is never advertised back to the

Type 3, 4, and 5 LSAs are replaced with a

summary-prefix IPv6-prefix [not-advertise]

point for all adjacencies on a

version 2

RIPv1

the AS to advertise a route external to OSPF

neighbor from which it was learned

default route

multiaccess segment

Original RIP implementation, limited to

! Originate a default route

Group Membership (Type 6)

! Disable RIPv2 automatic summarization

Poison Reverse

Not-So-Stubby Area (NSSA)

The BDR also maintains

classful routing (obsolete)

default-information originate [always]

Used by Multicast OSPF; unsupported by IOS

no auto-summary

Learned routes are advertised back to

A stub area containing an ASBR; type 5 LSAs

adjacencies with all routers in

RIPv2

NSSA External Link (Type 7)

their originator as explicitly invalid

are converted to type 7 within the area

! Designate stub, totally stubby, or not-so-stubby areas

case the DR fails

! Designate RIPv2 interfaces by network

Introduced support for classless routing,

Generated by an ASBR in a not-so-stubby area;

area area { stub | nssa } [no-summary]

network IPv4-network

Does not occur on point-to-

triggered updates, and multicast

Troubleshooting

External Route Types

converted into a type 5 LSA by the ABR when

point or multipoint links

! Create a virtual link

announcements (RFC 2453)

! Identify unicast-only neighbors

leaving the area

show ip[v6] protocols

Default priority (0-255) is 1;

area area virtual-link router-ID

neighbor IP-address

Considers the cost to the advertising ASBR

RIPng (RIP Next Generation)

show ip[v6] rip database

highest priority wins; 0 cannot

OSPFv3 Link State Advertisements

plus the external cost of the route

Extends RIPv2 to support IPv6 routing

! Originate a default route

be elected

debug ip rip { database | events }

interface type number

Name

v2 Equiv.

(RFC 2080); functions very similarly to

E2 (Default)

default-information originate

DR preemption will not occur

RIPv2 and is subsequently as limited

debug ipv6 rip [interface]

The external cost of a route as seen by the

! Enable OSPF on the interface

0x2001

Router LSA

Type 1

unless the current DR is reset

! Designate passive interfaces

ASBR; internal OSPF cost is not considered

ip[v6] ospf process-ID area area

0x2002

Network LSA

Type 2

RIP Configuration

passive-interface {interface | default}

Virtual Links

! Identify neighbors for NBMA links (OSPFv3)

0x2003

Inter-area prefix LSA

Type 3

Troubleshooting

! Modify equal-cost load balancing

Tunnel formed to join two

ipv6 ospf neighbor IPv6-address

interface type number

0x2004

Inter-area router LSA

Type 4

show ip[v6] ospf [process] interface

maximum-paths 1-16

areas across an intermediate

! Set interface cost manually

! Enable RIPng on the interface

0x4005

AS-external LSA

Type 5

show ip[v6] ospf [process] neighbor

Both end routers must share

! Modify timers

ip[v6] ospf cost 1-65535

ipv6 rip name enable

a common non-stub area

0x2006 Group membership LSA

Type 6

show ip[v6] ospf border-routers

timers basic update invalid hold flush

At least one end must reside

! Configure DR election priority

! Configure manual route summarization

0x2007

Type-7 LSA

Type 7

show ip[v6] ospf database [LSA-type]

! Enable RIPng IPv6 routing

in area 0

ip[v6] ospf priority 0-255

ip summary-address rip IPv4-address subnet-mask

ipv6 router rip name

0x0008

Link LSA

N/A

show ip[v6] ospf virtual-links

ipv6 rip name summary-address IPv6-prefix

Transition tool; not ideal for

! Specify network type (broadcast, point-to-point, etc.)

0x2009

Intra-area prefix LSA

N/A

debug ip[v6] ospf […]

permanent designs

! Toggle split-horizon and poison-reverse

ip[v6] ospf network type

! Enable MD5 authentication (RIPv2 only)

[no] split-horizon

ip rip authentication mode md5

! Modify interface hello and dead intervals

Network Types

[no] poison-reverse

ip rip authentication key-chain key-chain

ip[v6] ospf hello-interval seconds

Nonbroadcast

Multipoint

ip[v6] ospf dead-interval seconds

(NBMA)

Broadcast

Nonbroadcast

Broadcast

Point-to-Point

DR/BDR Elected

Yes

! Enable MD5 authentication (OSPFv2)

EIGRP

EIGRP Configuration

ip ospf authentication message-digest

Neighbor Discovery

Yes

ip ospf message-digest-key key-id md5 key-string

! Enable EIGRP for an autonomous system

Hello/Dead Timers

30/120

10/40

Metric Formula

[ipv6] router eigrp AS-number

! Enable IPsec authentication (OSPFv3)

Defined By

RFC 2328

Cisco

ipv6 ospf auth ipsec spi spi-number { md5 | sha1 } string

! Specify a router ID formatted in IPv4 dotted-decimal

256 * (K

+ K

* delay) *

Supported Topology

Full Mesh

Any

Full Mesh

Point-to-Point

256 -

load

rel

+ K

[eigrp] router-id router-ID

= 10

/ minimum path bandwidth in kbps

! Disable automatic classful summarization (IPv4 only)

delay

= interface delay in secs / 10

ISO Routing Levels

IS-IS Configuration

Integrated IS-IS

no auto-summary

Level 0

Used to locate end systems

Packet Types

Default K Values

! Enable EIGRP on interfaces by network (IPv4 only)

! Enable IS-IS routing

network IPv4-address wildcard-mask

NSAP Addressing

Level 1

Routing within an area (IS-IS)

router isis

1 Update

Level 2

Routing between areas (IS-IS)

3 Query

! Modify maximum paths for equal-cost load balancing

Interdomain Part

Domain-Specific Part

! Specify one or more NET addresses

maximum-paths 1-16

Level 3 Inter-AS routing

net NET

4 Reply

NSAP

AFI

IDI

HODSP

5 Hello

! Configure multiplier for unequal-cost load balancing

System ID

SEL

! Set global routing level (default level-1-2)

Terminology

Condensed

Area

variance 1-128

is-type { level-1 | level-1-2 | level-2-only }

8 Acknowledge

Type-Length-Value (TLV)

Example

0005.80ff.f800.0000

0001

0000.0c00.1234

! Configure K values to manipulate the metric formula

Variable-length modular datasets carried by PDUs

! Configure IPv4 route summaries

Terminology

metric weights 0 k1 k2 k3 k4 k5

summary-address IP-address subnet-mask [level]

Interdomain Part (IDP)

IS-IS Hello (IIH)

Reported Distance

Portion of the address used in routing between autonomous systems;

Establish and maintain neighbor adjacencies

! Explicitly identify neighbors on NBMA links

! Configure IPv6 route summaries

The metric for a route advertised by a neighbor

assigned by ISO

Link State PDU (LSP)

neighbor IP-address interface

address-family ipv6

Feasible Distance

Domain-Specific Part (DSP)

Carry TLVs encompassing link state information

summary-prefix IPv6-prefix [level]

The distance advertised by a neighbor plus the cost

! Designate passive interfaces

Portion of the address relevant only within the local AS

Sequence Number Packet (SNP)

to get to that neighbor

passive-interface {interface | default}

! Originate a default route

Used to request and advertise LSPs; can be complete

Authority and Format Identifier (AFI)

default-information originate

Stuck In Active (SIA)

Identifies the authority which dictates the format of the address

(CSNP) or partial (PSNP)

! Enable stub routing

The condition when a route becomes unreachable

Initial Domain Identifier (IDI)

Network Entity Title (NET)

[eigrp] stub [receive-only | connected | static | summary | redist]

and not all queries for it are answered; adjacencies

interface type number

An organization belonging to the AFI

Unique router ID; includes area ID

with unresponsive neighbors are reset

High Order DSP (HODSP)

Designated Intermediate System (DIS)

interface type number

! Enable IS-IS on an interface

Passive Interface

The area within the AS

A pseudonode responsible for emulating point-to-

ip[v6] router isis

An interface which does not participate in EIGRP

! Enable EIGRP for IPv6 on the interface

System ID

point links across a multi-access segment

but whose network is advertised

ipv6 eigrp AS-number

! Specify interface routing level

Unique router identifier; 48 bits for Cisco devices (often taken from an

Adjacency Requirements

isis circuit-type { level-1 | level-1-2 | level-2-only }

Stub Router

Ethernet MAC address)

! Set the maximum bandwidth EIGRP can consume (can be >100%)

A router which advertises only a subset of routes,

Interface MTUs must match

NSAP Selector (SEL)

ip[v6] bandwidth-percent eigrp AS-number 1-999999

! Set interface metric

and is omitted from the route query process

Identifies a network layer service; always 0x00 in a NET

Levels must match

isis [ipv6] metric { 1-16777214 | maximum }

! Configure manual summarization of outbound routes

Default Timers

ip summary-address eigrp AS-number IPv4-address subnet-mask [AD]

Areas must match (if level 1)

! Designate the network as point-to-point

Network Types

ipv6 summary-address eigrp AS-number IPv6-prefix [AD]

isis network point-to-point

LAN (>T1)

WAN (<=T1)

System IDs must be unique

Broadcast

Point-to-Point

Hello 5 sec

60 sec

DIS Elected Yes

Authentication must succeed

! Configure DIS election priority

! Enable MD5 authentication

ip[v6] authentication mode eigrp AS-number md5

isis priority 0-127 [ level-1 | level-2 ]

Hold 15 sec

180 sec

Neighbor Discovery Yes

Yes

DIS Election

ip[v6] authentication key-chain eigrp AS-number key-chain

! Modify interface hello and dead intervals

Hello/Dead Timers 10/30

10/30

Troubleshooting

Highest-priority interface elected

isis hello-interval seconds [ level-1 | level-2 ]

! Modify interface hello and hold timers

show ip[v6] eigrp {interfaces | neighbors }

ip[v6] hello-interval eigrp AS-number seconds

Troubleshooting

Highest SNPA (e.g. MAC or DLCI) breaks tie

isis hello-multiplier 3-1000 [ level-1 | level-2 ]

ip[v6] hold-time eigrp AS-number seconds

show ip[v6] eigrp topology

show [clns | isis] neighbors

show isis [database | spf-log]

Highest system ID breaks SNPA tie

! Enable MD5 authentication

isis authentication mode md5

clear ip[v6] eigrp [AS-number] neighbors

! Toggle split horizon

show clns interface

debug [clns | isis] […]

Default interface priority is 64

[no] ip[v6] split-horizon eigrp AS-number

isis authentication key-chain key-chain

debug ip[v6] eigrp [neighbor]

show isis [ipv6] topology

Current DIS may be preempted, unlike OSPF

Cisco Ios Interior Routing Protocols

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