Tylogix.com -> Cisco Routing Protocol Notes

Routing Abbreviation	Routing Protocol	Administrative Distance
C	Connected	0
S	Static	1
	EIGRP Summary Route	5
B	BGP	20
D	EIGRP (internal)	90
I	IGRP	100
N2	OSPF NSSA External Type 2	110
N1	OSPF NSSA External Type 1	110
E2	OSPF External Type 2	110
E1	OSPF External Type 1	110
L2	IS-IS - Level 2	115
L1	IS-IS - Level 1	115
ia	IS-IS Inter Area	115
i	IS-IS	115
R	RIP	120
E	EGP	140
O	ODR	160
EX	EIGRP External	170
	BGP (internal)	200
	DHCP-Learned	254
	Unknown	255
	EIGRP Summary Route

SWITCH

Spanning Tree

Rapid Spanning Tree Protocol (RSTP) Bridge Port Roles

Root - A forwarding port that is the best port from Nonroot-bridge to Rootbridge

Designated - A forwarding port for every LAN segment

Alternate - An alternate path to the root bridge. This path is different than using the root port.

Backup - A backup/redundant path to a segment where another bridge port already connects.

Disabled - Not strictly part of STP, a network administrator can manually disable a port

STP switch port states:

Blocking - A port that would cause a switching loop, no user data is sent or received but it may go into forwarding mode if the other links in use were to fail and the spanning tree algorithm determines the port may transition to the forwarding state. BPDU data is still received in blocking state.

Listening - The switch processes BPDUs and awaits possible new information that would cause it to return to the blocking state.

Learning - While the port does not yet forward frames (packets) it does learn source addresses from frames received and adds them to the filtering database (switching database)

Forwarding - A port receiving and sending data, normal operation. STP still monitors incoming BPDUs that would indicate it should return to the blocking state to prevent a loop.

Disabled - Not strictly part of STP, a network administrator can manually disable a port

LAN

Router Rip

LAN Router RIP	RIP General Concept	Routers running IP RIP broadcast the full list of all the routes they know every 30 seconds. When a router running RIP hears a broadcast it runs the distance vector algorithm to create a list of best routes.
	RIP Timers	Timer	Default	Controls
		Update	30 seconds	Interval between route update advertizements
		Hold-Down	90 seconds	Period a route is withdrawn from the table to prevent a routing loop
		Timeout	180 seconds	Interval a route should stay "live" in the routing table. This counter is reset every time the router hears an update for this route
		Flush	120 seconds	How long to wait before deleting a route after it has timed out.
	Basic Configuration	router(config)# router rip router(config-router)# network 192.168.42.0 router(config-router)# network 192.168.43.0

LAN

EIGRP

EIGRP General Concept

EIGRP stores data in three tables:

Neighbor Table: Stores data about the neighboring routers, i.e. those directly accessible through directly connected interfaces.

Topology Table: Confusingly named, this table does not store an overview of the complete network topology; rather, it effectively contains only the aggregation of the routing tables gathered from all directly connected neighbors. This table contains a list of destination networks in the EIGRP-routed network together with their respective metrics. Also for every destination, a successor and a feasible successor are identified and stored in the table if they exist. Every destination in the topology table can be marked either as "Passive", which is the state when the routing has stabilized and the router knows the route to the destination, or "Active" when the topology has changed and the router is in the process of (actively) updating its route to that destination.

Routing table: Stores the actual routes to all destinations; the routing table is populated from the topology table with every destination network that has its successor and optionally feasible successor identified (if unequal-cost load-balancing is enabled using the variance command). The successors and feasible successors serve as the next hop routers for these destinations.

Unlike most other distance vector protocols, EIGRP does not rely on periodic route dumps in order to maintain its topology table. Routing information is exchanged only upon the establishment of new neighbor adjacencies, after which only changes are sent. Also, it uses route tagging.

Basic Configuration

router eigrp 10   (10 here is the Autonomous System Number)

network 172.16.0.0

LAN

OSPF

OSPF Single-Area Configuration

interface Ethernet 0/0
ip address 10.1.1.1 255.255.255.0
interface serial 0/0
ip address 10.1.4.1 255.255.255.0

router ospf 1
network 10.0.0.0 0.255.255.255 area 0

Network : What interfaces you want to include in OSPF configuration . Here 10.0.0.0
Wildcard Mask: If bit set to 1, "don’t care" bit (and 0 = include) . Here 0.255.255.255
Area : What area this router is in. Here area 0

OSPF Configuration with Multiple Areas

If router has interfaces in multiple areas:

router ospf 1
network 10.1.1.1 0.0.0.0 area 0
network 10.1.4.1 0.0.0.0 area 1
network 10.1.6.1 0.0.0.0 area 0

Useful Commands
show ip ospf interface ->Details IP address, area , Router ID, Hello/Dead Interval, etc. for all interfaces

show ip route -> Shows all routes known by the router (C – Connected, O – OSPF)

show ip ospf neighbor -> Shows the routers ospf neighbors

Remember that the RID is that router’s highest IP address on a physical interface when OSPF starts running. Alternatively, if a loopback interface has been configured, OSPF uses the highest IP address on a loopback interface for the RID, even if that IP address is lower than some physical interface’s IP address.

OSPF Troubleshooting

· View neighbors:
show ip ospf neighbor ->Output doesn’t show neighbors

· Run debugging:
debug ip ospf hello -> Output shows mismatched Hello interval

· To identify the interface:
show ip ospf interface [interface] -> Will give you the hello interval (which can be mismatched)

· To change hello interval for that interface:
configure terminal
itinterface [interface]
ip ospf hello [count]
exit

WAN

BGP

Wide Area Network Communications

Frame Relay	Configuring Frame Relay	Mandatory commands	Optional Commands
	Configuring Frame Relay	assigning an IP address o ip address setting the encapsulation type o encapsulation frame-relay allocating bandwidth o bandwidth	Configure the LMI Configure Frame Relay SVCs Configure Frame Relay traffic shaping Customize Frame Relay for your network Monitor and Maintain Frame Relay connections
	Example Configuration	R1(config)#interface serial0/0/0 R1(config-if)#encapsulation frame-relay R1(config-if)#no shutdown Static Configuration (DLCI 102 belongs to R1): R1(config-if)#frame-relay map ip 10.1.1.2 102 broadcast R1(config-if)#frame-relay lmi-type ansi Sub-Interface configuration (optional): R1(config-if)#interface serial 0/0/0.102 point-to-point R1(config-if)#interface-dlci 102 R1(config-if)#interface serial 0/0/0.103 point-to-point R1(config-if)#interface-dlci 103	Notes Each Virtual Circuit is tagged with an identifier to keep it unique. The identifier, known as a Data Link Connection Identifier (DLCI), is determined on a per-leg basis during the transmission. Local Management Interface (LMI) is the means by which Frame Relay edge devices maintain keepalive messages. The Frame Relay switch is responsible for maintaining the status of the CPE device(s) to which it is attached.
	Debug	show interfaces show frame-relay lmi look for any non-zero "Invalid" items debug frame-relay lmi show frame-relay pvc [interfaceinterface] [dlci] to view PVC and traffic statistics clear counters command to reset the statistics counters R1(config-if)#interface-dlci 102 Show frame-relay map To show the frame-relay map To show the Local Management Interface (LMI) - LMI is a keep-alive (10 second) mechanism that provides status information about Frame Relay connections between the router (DTE) and the Frame Relay switch (DCE) Show frame-relay lmi

PPP

PPP Protocol Stack

Application	FTP / SMTP / HTTP / etc....	DNS...
Transport	TCP	UDP
Internet	IPv4 / IPv6
Network Access	PPP
	PPPoE	PPPoA
	Ethernet	ATM

PPP Architecture (Data Link Layer)

LCP	CHAP / PAP / EAP	IPCP	IP
PPP Encapsulation
HDLC-like Framing		PPPoE	PPPoA
RS-232	POS	Ethernet	ATM
	SONET/SDH

PPP

Link Control Protocol

This protocol is used to establish, configure and test the data-link connection for a PPP link.

In order to establish communications over a point-to-point link, each end of the PPP link MUST first send LCP packets to configure and test the data link. After the link has been established, the peer MAY be authenticated.

LCP negotiates

- Link quality / Error detection

- Authentication (PAP / CHAP)

- Compression

Circuit Choices

Option	Description	Advantages	Disadvantages	Sample Link Types
Leased Line	Point-to-Point connection between two LAN's	Most Secure	Expensive	PPP HDLC SDLC HNAS
Circuit Switching	Dedicated circuit path created between endpoints. Best example: Dialup.	Less Expensive	Long call setup	PPP ISDN
Packet Switching	Device transport packets via a shared single point-to-point or point-to-multipoint link across a carrier network. Variable-length packets are transmitted over permanent virtual Circuits (PVC's) or Switched Virtual Circuits (SVC's)	Widely supported and less expensive than leased line	Shared media across link	X.25 Frame Relay
Cell Relay	Similar to Packet Switching but uses fixed-length cells instead of variable-length packets. Data is divided into fixed-length cells and then transported across virtual circuits.	Best for simulated use of voice and data	Overhead can be considerable (20%+)	ATM
Internet	Connectionless packet switching using the Internet as the WAN infrastructure, uses network addressing to deliver packets. Because of security, VPN technology must be used.	Least expensive Widely Available	Least secure	VPN DSL Cable Modem Wireless

Three Layers of the Architecture Network Model

Model	Description
Access Layer	User-level access to the network
Distribution Layer	Aggregates wiring closets, using switches to segment workgroups and isolate network problems.
Core Layer (Backbone)	High-speed backbone designed to switch packets as fast as possible

5 Modules of Cisco Enterprise Architecture

Module	Description
Enterprise Campus Architecture	Building or group of buildings connected to ONE NETWORK
Enterprise Branch Architecture	Enables extending applications and services found at the Campus to remote locations
Enterprise Data Center Architecture	Centrally house data and resources necessary for the enterprise functions
Enterprise Teleworker Architecture	Allow teleworkers into the enterprise, typically via remote access VPN's
Enterprise Edge Architecture	Liaison between Campus module and other modules in the Enterprise Architecture