Network Analyst: 03/09/10

RGMP: Cisco Router Port Group Management Protocol

RGMP: Cisco Router Port Group Management Protocol

The Cisco Router Port Group Management Protocol (RGMP) is defined to address the limitations of Internet Group Management Protocol (IGMP) in its Snooping mechanism. RGMP is used between multicast routers and switches to restrict multicast packet forwarding in switches to those routers where the packets may be needed. RGMP is designed for backbone switched networks where multiple, high speed routers are interconnected.

The main limitation of IGMP Snooping is that it can only restrict multicast traffic onto switch ports where receiving hosts are connected directly or indirectly via other switches. IGMP Snooping can not restrict multicast traffic to ports where at least one multicast router is connected. It must instead flood multicast traffic to these ports. Snooping on IGMP messages alone is an intrinsic limitation. Through it, a switch can only learn which multicast flows are being requested by hosts. A switch can not learn through IGMP which traffic flows need to be received by router ports to be routed because routers do not report these flows via IGMP.

The RGMP protocol restricts multicast traffic to router ports. To effectively restrict traffic, it must be supported by both the switches and the routers in the network.

Backbone switches use RGMP to learn which groups are desired at each of their ports. Multicast routers use RGMP to pass such information to the switches. Only routers send RGMP messages. They ignore received RGMP messages. When a router no longer needs to receive traffic for a particular group, it sends an RGMP Leave message for the group. A switch enabled for RGMP on a network consumes RGMP messages received from ports of the network and processes them. If enabled for RGMP, the switch must NOT forward/flood received RGMP messages out to other ports of the network.

RGMP is designed to work in conjunction with multicast routing protocols where explicit join/prune to the distribution tree is performed. PIM-SM is an example of such a protocol. The RGMP protocol specifies operations only for IP version 4 multicast routing. IP version 6 is not considered.

Protocol Structure - RGMP: Cisco Router Port Group Management ProtocolRGMP message format is the same as the IGMPv2:

8	16	32bit
Type	Reserved	Checksum
Group Address

Type - There are four types of RGMP messages of concern to the router-switch interaction. The type codes are defined to be the highest values in an octet to avoid the re-use of already assigned IGMP type codes: 0xFF = Hello; 0xFE = Bye; 0xFD = Join a group; 0xFC = Leave a group.
Reserved - The reserved field in the message MUST be transmitted as zeros and ignored on receipt.
Checksum - Checksum covers the RGMP message (the entire IPv4 payload). The algorithm and handling of checksum are the same as those for IGMP messages.
Group Address - In an RGMP Hello or Bye message, the group address field is set to zero. In an RGMP Join or Leave message, the group address field holds the IPv4 multicast group address of the group being joined or left.

IGMP: Internet Group Management Protocol Overview

IGMP: Internet Group Management Protocol Overview

(IGMPv1, IGMPv2 and IGMPv3)

Internet Group management protocol (IGMP), a multicasting protocol in the internet protocols family, is used by IP hosts to report their host group memberships to any immediately neighboring multicast routers. IGMP messages are encapsulated in IP datagrams, with an IP protocol number of 2. IGMP has versions IGMP v1, v2 and v3.

IGMPv1: Hosts can join multicast groups. There were no leave messages. Routers were using a time-out based mechanism to discover the groups that are of no interest to the members.
IGMPv2: Leave messages were added to the protocol. Allow group membership termination to be quickly reported to the routing protocol, which is important for high-bandwidth multicast groups and/or subnets with highly volatile group membership.
IGMPv3: Major revision of the protocol. It allows hosts to specify the list of hosts from which they want to receive traffic from. Traffic from other hosts is blocked inside the network. It also allows hosts to block inside the network packets that come from sources that sent unwanted traffic.

The variant protocols of IGMP are:

DVMRP: Distance Vector Multicast Routing Protocol.
IGAP: IGMP for user Authentication Protocol.
RGMP: Router-port Group Management Protocol.

Protocol Structure -IGMP (Internet Group Management Protocol)

There are basically 5 types of messages in the IGMP that must be implemented in IGMP for the IGMP v3 functional properly and be compatible with previous versions:

0x11: membership query

0x22: version 3 membership report
0x12: version 1 membership report
0x16: version 2 membership report
0x17 version 2 leave group

As an example, the message format for 0x11 (membership query) is displayed as follows:

8		16		32 bit
Type		Max response time		Checksum
Group address
RSV	S	QRV	QQIC	Number of Source
Source Address (1)
...
Source Address (N)

Type -- The message type: 0x11 (Membership query).
Max Response Time -- Used only in Membership query messages. Specifies the maximum time allowed before sending a responding report in units of 1/10 second. In all other messages, it is set to 0 by the sender and ignored by the receiver.
Checksum -- The checksum for messages errors
Group Address -- The Group address is set to 0 when sending a general query. It is set to the group address being queried, when sending a group specific query or group-and-source-specific query. In a membership report of a leave group message, it holds the IP multicast group address of the group being reported or left.
RSV - Reserved; Set to zero on transmission, and ignored on reception.
QQIC - Querier's Query Interval Code
Number of Source (N) -- The number of source addresses in this message.
Source Address - the vector of the IP unicast address.
Group Record -- A block of fields containing information about the sender's membership in a single multicast group, on the interface from which the report is sent.

The details of other message types can be found in the reference RFC 1112, 2236 and 3376.

ICMP & ICMPv6: Internet Message Control Protocol and ICMP version 6

ICMP & ICMPv6: Internet Message Control Protocol and ICMP version 6

Internet Control Message Protocol (ICMP) is an integrated part of IP suite. ICMP messages, delivered in IP packets, are used for out-of-band messages related to network operation or mis-operation. ICMP packet delivery is unreliable, so hosts can't count on receiving ICMP packets for any network problems. The key ICMP functions are:

Announce network errors, such as a host or entire portion of the network being unreachable, due to some type of failure. A TCP or UDP packet directed at a port number with no receiver attached is also reported via ICMP.
Announce network congestion. When a router begins buffering too many packets, due to an inability to transmit them as fast as they are being received, it will generate ICMP Source Quench messages. Directed at the sender, these messages should cause the rate of packet transmission to be slowed. Of course, generating too many Source Quench messages would cause even more network congestion, so they are used sparingly.
Assist Troubleshooting. ICMP supports an Echo function, which just sends a packet on a round--trip between two hosts. Ping, a common network management tool, is based on this feature. Ping will transmit a series of packets, measuring average round--trip times and computing loss percentages.

Announce Timeouts. If an IP packet's TTL field drops to zero, the router discarding the packet will often generate an ICMP packet announcing this fact. TraceRoute is a tool which maps network routes by sending packets with small TTL values and watching the ICMP timeout announcements.

The Internet Control Message Protocol (ICMP) was revised during the definition of IPv6. In addition, the multicast control functions of the IPv4 Group Membership Protocol (IGMP ) are now incorporated with the ICMPv6.

Protocol Structure - ICMP & ICMPv6 Internet Message Control Protocol

8	16	32 bit
Type	Code	Checksum
Identifier		Sequence number
Address mask

Type -- Messages can be error or informational messages. Error messages can be Destination unreachable, Packet too big, Time exceed, Parameter problem. The possible informational messages are, Echo Request, Echo Reply, Group Membership Query, Group Membership Report, Group Membership Reduction.

Code -- For each type of message several different codes are defined. An example of this is the Destination Unreachable message, where possible messages are: no route to destination, communication with destination administratively prohibited, not a neighbor, address unreachable, port unreachable. For further details, refer to the standard.
Checksum -- The 16-bit one's complement of the one's complement sum of the ICMP message starting with the ICMP Type. For computing the checksum, the checksum field should be zero.
Identifier -- An identifier to aid in matching requests/replies; may be zero.
Sequence number -- Sequence number to aid in matching requests/replies; may be zero.
Address mask -- A 32-bit mask

TCP: Transmission Control Protocol

TCP: Transmission Control Protocol

Transmission Control Protocol (TCP) is the transport layer protocol in theTCP/IP protocol suite , which provides a reliable stream delivery and virtual connection service to applications through the use of sequenced acknowledgment with retransmission of packets when necessary. Along with the Internet Protocol (IP ), TCP represents the heart of the Internet protocols.

Since many network applications may be running on the same machine, computers need something to make sure the correct software application on the destination computer gets the data packets from the source machine, and some way to make sure replies get routed to the correct application on the source computer. This is accomplished through the use of the TCP "port numbers". The combination of IP address of a network station and its port number is known as a socket or an "endpoint". TCP establishes connections or virtual circuits between two "endpoints" for reliable communications. Details of TCP port numbers could be found in the TCP/UDP Port Number document and in the reference.

Among the services TCP provides are stream data transfer, reliability, efficient flow control, full-duplex operation, and multiplexing.

With stream data transfer,TCP delivers an unstructured stream of bytes identified by sequence numbers. This service benefits applications because that the application does not have to chop data into blocks before handing it off to TCP. TCP can group bytes into segments and passes them to IP for delivery.

TCP offers reliability by providing connection-oriented, end-to-end reliable packet delivery. It does this by sequencing bytes with a forwarding acknowledgment number that indicates to the destination the next byte the source expects to receive. Bytes not acknowledged within a specified time period are retransmitted. The reliability mechanism of TCP allows devices to deal with lost, delayed, duplicate, or misread packets. A time-out mechanism allows devices to detect lost packets and request retransmission.

TCP offers efficient flow control - when sending acknowledgments back to the source, the receiving TCP process indicates the highest sequence number it can receive without overflowing its internal buffers.

Full-duplex operation: TCP processes can both send and receive packets at the same time.

Multiplexing in TCP: numerous simultaneous upper-layer conversations can be multiplexed over a single connection.

Protocol Structure - TCP Transmission Control Protocol

16								32 bit
Source port								Destination port
Sequence number
Acknowledgement number
Offset	Reserved	U	A	P	R	S	F	Window
Checksum								Urgent pointer
Option + Padding
Data

Source port -- Identifies points at which upper-layer source process receives TCP services.
Destination port -- Identifies points at which upper-layer Destination process receives TCP services.
Sequence number -- Usually specifies the number assigned to the first byte of data in the current message. In the connection-establishment phase, this field also can be used to identify an initial sequence number to be used in an upcoming transmission.
Acknowledgment number - It contains the sequence number of the next byte of data the sender of the packet expects to receive. Once a connection is established, this value is sent.
Data offset -- 4 bits. The number of 32-bit words in the TCP header indicates where the data begins.
Reserved -- 6 bits. Reserved for future use. Must be zero.
Control bits (Flags) -- 6 bits. It carries a variety of control information.
Window -- 16 bits. It specifies the size of the sender's receive window, that is, the buffer space available in octets for incoming data.
Checksum -- 16 bits. It indicates whether the header was damaged in transit.
Urgent Pointer -- 16 bits. it points to the first urgent data byte in the packet.
Option + Paddling - Specifies various TCP options. There are two possible formats for an option: A single octet of option type. An octet of option type, an octet of option length, and the actual option data octets.
Data - contains upper-layer information.

UDP: User Datagram Protocol

UDP: User Datagram Protocol

UDP is a connectionless transport layer (layer 4) protocol in OSI model, which provides a simple and unreliable message service for transaction-oriented services. UDP is basically an interface between IP and upper-layer processes. UDP protocol ports distinguish multiple applications running on a single device from one another.

Since many network applications may be running on the same machine, computers need something to make sure the correct software application on the destination computer gets the data packets from the source machine, and some way to make sure replies get routed to the correct application on the source computer. This is accomplished through the use of the UDP "port numbers". For example, if a station wished to use a Domain Name System (DNS) on the station 128.1.123.1, it would address the packet to station 128.1.123.1 and insert destination port number 53 in the UDP header. The source port number identifies the application on the local station that requested domain name server, and all response packets generated by the destination station should be addressed to that port number on the source station. Details of UDP port numbers could be found in the TCP/UDP Port Number document and in the reference.

Unlike the TCP , UDP adds no reliability, flow-control, or error-recovery functions to IP. Because of UDP's simplicity, UDP headers contain fewer bytes and consume less network overhead than TCP.

UDP is useful in situations where the reliability mechanisms of TCP are not necessary, such as in cases where a higher-layer protocol might provide error and flow control, or real time data transportation is required.

UDP is the transport protocol for several well-known application-layer protocols, including Network File System (NFS) , Simple Network Management Protocol (SNMP) , Domain Name System (DNS) , and Trivial File Transfer Protocol (TFTP).

Integrated Services Digital Network (ISDN)

ROUTER A-CISCO

A-CISCO#configure terminal

A-CISCO (config)#isdn switch-type basic-net3

A-CISCO (config)# dialer-list 1 protocol ip permit

A-CISCO (config)#interface bri0

A-CISCO (config-if)#ip address 1.1.1.1 255.0.0.0

A-CISCO (config-if)#encapsulation ppp

A-CISCO (config-if)#dialer-group 1

A-CISCO (config-if)#dialer map ip 1.1.1.2 2451458

A-CISCO (config-if)#dialer idle-timeout 180

ROUTER B-CISCO

B-CISCO#configure terminal

B-CISCO (config)#isdn switch-type basic-net3

B-CISCO (config)# dialer-list 1 protocol ip permit

B-CISCO (config)#interface bri0

B-CISCO (config-if)#ip address 1.1.1.2 255.0.0.0

B-CISCO (config-if)#encapsulation ppp

B-CISCO (config-if)#dialer-group 1

B-CISCO (config-if)#dialer map ip 1.1.1.1 2051458

B-CISCO (config-if)#dialer idle-timeout 180

Current Configuration

version 12.0

service timestamps debug uptime

no service password-encryption

hostname A-CISCO

enable password cisco

isdn switch-type basic-net3

interface BRI 0

ip address 1.1.1.1 255.0.0.0

encapsulation ppp

dialer map ip 1.1.1.2 2451458

dialer group 1

dialer idle-timeout 180

dialer-list 1 protocol ip permit

line con 0

end

Current Configuration

version 12.0

service timestamps debug uptime

no service password-encryption

hostname B-CISCO

enable password cisco

isdn switch-type basic-net3

interface BRI 0

ip address 1.1.1.2 255.0.0.0

encapsulation ppp

dialer map ip 1.1.1.2 2051458

dialer group 1

dialer-list 1 protocol ip permit

line con 0

transport input none

line aux 0

line vty 0 4

no login

end

Common Frame Relay Configuration

Frame Relay Switch

FRAMRELAY-SWITCH#configure terminal

FRAMRELAY-SWITCH(config)#frame-relay switching

FRAMRELAY-SWITCH(config)#int s0

FRAMRELAY-SWITCH(config-if)#no ip address

FRAMRELAY-SWITCH(config-if)#encapsulation frame-relay

FRAMRELAY-SWITCH(config-if)#clock rate 64000

FRAMRELAY-SWITCH(config-if)#frame-relay lmi-type ansi

FRAMRELAY-SWITCH(config-if)#frame-relay intf-type dce

FRAMRELAY-SWITCH(config-if)#frame-relay route 103 interface s1 301

FRAMRELAY-SWITCH(config-if)#exit

FRAMRELAY-SWITCH(config)#int s1

FRAMRELAY-SWITCH(config-if)#no ip address

FRAMRELAY-SWITCH(config-if)#encapsulation frame-relay

FRAMRELAY-SWITCH(config-if)#clock rate 64000

FRAMRELAY-SWITCH(config-if)#frame-relay lmi-type ansi

FRAMRELAY-SWITCH(config-if)#frame-relay intf-type dce

FRAMRELAY-SWITCH(config-if)#frame-relay route 301 interface s0 103

Router A Configuration

RouterA#configure terminal

RouterA(config)#int s0/0

RouterA(config)#ip address 10.0.0.1 255.0.0.0

RouterA(config)#encapsulation frame-relay

RouterA(config)#frame-relay lmi-type ansi

Router B Configuration

RouterB#configure terminal

RouterB(config)#int s0/1

RouterB(config)#ip address 10.0.0.2 255.0.0.0

RouterB(config)#encapsulation frame-relay

RouterB(config)#frame-relay lmi-type ansi

Standard IP Access Control List

RouterA#configure terminal

RouterA(config)#access-list 1 remark stop all traffic whose source ip 1.1.1.2

RouterA(config)#access-list 1 deny 1.1.1.2 0.0.0.0

RouterA(config)#access-list 1 permit any

RouterA(config)#int s0/0

RouterA(config-if)#ip access-group 1 in

RouterA#show access-lists

Standard IP access list 1

Deny 1.1.1.2

Permit any

Now verify these configuration on router with command us under:

RouterA#show ip int s0/0

Useful Router commands and configuration

Router (Router commands) working with two main ports, configuration and communication port. We manage all router setting using configuration port. Here are some useful router commands to manage router configuration.

Set Line Console Password

router>enable
router#configure terminal
router(config)#line console 0
router(config-line)#login
router(config-line)#password submask
router(config-line)#exit
router(config)#exit

Remove Console password

router>enable
router#configure terminal
router(config)#line console 0
router(config-line)#no login
router(config-line)#no password
router(config-line)#exit
router(config)#exit

Remove Secret Password

router>enable
router#configure terminal
router(config)#no enable secret
router(config)#exit

How to check Configuration Register Value

router>enable
router#show version

How to Administratively shutdown Router's Interface

router>enable
router#configure terminal
router(config)#int s0/0
router(config-if)#shutdown

To Enable Router's Serial Interface

router#configure terminal
router(config)#int s0/0
router(config-if)#no shutdown

To check Serial Interface

router>enable
router(config)#show interfaces s0/0

To set Clock rate on Router's Serial Interface

router>enable
router#configure terminal
router(config)#interface s0/0
router(config-if)#clock rate 64000

DTE/DCE Status

router>enable
router#show controllers s0/0

To Save Running Configuratoin

router#copy running-config startup-config

IOS uploading from Router to TFTP Server

router#copy flash: tftp

Backup Startup Configuration to TFTP

router#copy startup-config tftp

To Save Running Configuration

router#write memory

Deletion of NVRAM Configuration

router#write erase

To check NVRAM Configuration

router#show staratup-config

Extended IP Access Control List

RouterA(config)#access-list 103 remark stop telnet to router A whose source ip 1.1.1.2

RouterA(config)#access-list 103 deny tcp host 1.1.1.2 host 1.1.1.2 eq 23

RouterA(config)#access-list 103 permit ip any

RouterA(config)#int s0/0

RouterA(config-if)#ip access-group 103 in

RouterA#show access-lists

Extended ip access list 103

Deny tcp host 1.1.1.2 host 1.1.1.1 eq telnet(2 matches)

Permit ip any (160 matches)

Point-To-Point Leased Line Implementation

Point-To-Point Leased Line Implementation

Current configuration:

version 12.0

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

hostname A-cisco

username B-cisco password 0 Jonn

interface SeriaIO/0

ip address 1.1. I.I 255.0.0.0 encapsulation ppp

ppp authentication chap

line con 0

transport input none

line aux 0

line vty 0 4

no login

end

Current configuration:

version 12.0

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

hostname B-cisco

username A-cisco password 0 Jonn

interface SeriaIO/0

ip address 1.1. I.2 255.0.0.0 encapsulation ppp

ppp authentication chap

ip classless

no ip http server

line con 0

transport input none

line aux 0

line vty 0 4

no login

end

Routing Information Protocol (RIP) Configuration

RouterA#show ip route

Gateway of last resort is not set

C 1.0.0.0/8 is directly connected, serial0/1

C 3.0.0.0/8 is directly connected, serial0/0

C 192.168.1.0/24 is directly connected, loopback0

Configure RIP on Router A

RouterA#configure terminal

RouterA#(config)#router rip

RouterA#(config-router)#network 3.0.0.0

RouterA#(config-router)#network 1.0.0.0

RouterA#(config-router)#network 192.168.1.0

RouterA#(config-router)#exit

RouterA#(config)#

Now verify these configuration on router A with command us under:

RouterA#show ip route

To check the routing protocol with this command.

RouterA#show ip protocols

RouterB#show ip route

Gateway of last resort is not set

C 1.0.0.0/8 is directly connected, serial0/1

C 2.0.0.0/8 is directly connected, serial0/0

C 192.168.1.0/24 is directly connected, loopback0

Configure RIP on Router B

RouterB#configure terminal

RouterB#(config)#router rip

RouterB#(config-router)#network 1.0.0.0

RouterB#(config-router)#network 2.0.0.0

RouterB#(config-router)#network 192.168.2.0

RouterB#(config-router)#exit

RouterB#(config)#

Now verify these configuration on router B with command us under:

RouterB#show ip route

RouterC#show ip route

Gateway of last resort is not set

C 2.0.0.0/8 is directly connected, serial1

C 3.0.0.0/8 is directly connected, serial0

C 192.168.3.0/24 is directly connected, loopback0

Configure RIP on Router C

RouterC#configure terminal

RouterC#(config)#router rip

RouterC#(config-router)#network 2.0.0.0

RouterC#(config-router)#network 3.0.0.0

RouterC#(config-router)#network 192.168.3.0

RouterC#(config-router)#exit

RouterC#(config)#

Now verify these configuration on router C with command us under:

RouterC#show ip route

Break or recover the router password

Turn the power switch off and back on to recycle the power.
Press the Break key or key sequence to put the router into ROM Monitor mode. The break key varies by computer or terminal software. The sequence might be CTRL-D, CTRL-Break or another combination.
At the > prompt, type 0 to record the current value of the configuration register normally 0x2102, or 0x102.

>o

Configuration register = 0x2102 at last boot

Bit# Configuration register option settings:

15 Diagnostic mode disabled.
Type o/r 0x2142 to tell the router to boot from flash without loading the configuration in NVRAM at the next reload.
Type i to have the router reboot. The router ignores the configuration in NVRAM.
The router runs the setup dialog, Type no or press Ctrl-C to skip the initial setup Dialog.
Type enable ate the Router> prompt to go to privileged exec mode.
Copy the startup configuration to the running configuration by using the configure memory or copy startup-config running-config commands. Do not type configure terminal. If you use the configure terminal command, you overwrite the configuration stored in NVRAM.
View the configuration by typing write terminal or show running-config. View the configured line, vty and enable passwords. Any encrypted passwords need to be changed.
Enter the configuration mode by typing configure terminal. Change the line of enable passwords as necessary.
All interfaces are in a shutdown state. Issue the no shutdown command on every interface that is to be used.
Type config-register 0x2102 to return the router to normal operation at the next reloads.
Exit configuration mode by pressing Ctrl-Z
Save your changes by typing write memory or copy running-config startup-config.

Reload the router and verify the passwords.

IGRP Configuration

IGRP Configuration

RouterA#show ip route

Gateway of last resort is not set

C 1.0.0.0/8 is directly connected, serial0/1

C 3.0.0.0/8 is directly connected, serial0/0

C 192.168.1.0/24 is directly connected, loopback0

Configure igrp on Router A

RouterA#configure terminal

Enter configuration commands, one per line. End with Cntl/z

RouterA#(config)#router igrp 10

RouterA#(config-router)#network 1.0.0.0

RouterA#(config-router)#network 3.0.0.0

RouterA#(config-router)#network 192.168.1.0

RouterA#(config-router)#exit

RouterA#(config)#

Now verify these configuration on router A with command us under:

RouterA#show ip route

To check the routing protocol with this command.

RouterA#show ip protocols

RouterB#show ip route

Gateway of last resort is not set

C 1.0.0.0/8 is directly connected, serial0/1

C 2.0.0.0/8 is directly connected, serial0/0

C 192.168.2.0/24 is directly connected, loopback0

Configure igrp on Router B

RouterB#configure terminal

RouterB#(config)#router igrp 10

RouterB#(config-router)#network 1.0.0.0

RouterB#(config-router)#network 2.0.0.0

RouterB#(config-router)#network 192.168.2.0

RouterB#(config-router)#exit

RouterB#(config)#

Now verify these configuration on router B with command us under:

RouterB#show ip route

RouterC#show ip route

Gateway of last resort is not set

C 2.0.0.0/8 is directly connected, serial1

C 3.0.0.0/8 is directly connected, serial0

C 192.168.3.0/24 is directly connected, loopback0

Configure igrp on Router C

RouterC#configure terminal

RouterC#(config)#router igrp 10

RouterC#(config-router)#network 2.0.0.0

RouterC#(config-router)#network 3.0.0.0

RouterC#(config-router)#network 192.168.3.0

RouterC#(config-router)#exit

RouterC#(config)#

Now verify these configuration on router C with command us under:

RouterC#show ip route