Simulating a Frame Relay Cloud
Problem
You want to use a router to simulate a Frame Relay cloud in the lab.
Solution
A Cisco router can function as a Frame Relay switch. This is mostly useful when you are trying to simulate a Frame Relay cloud in a lab to test your router configurations:
Cloud#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Cloud(config)#frame-relay switching Cloud(config)#interface Serial0 Cloud(config-if)#description Frame-relay connection to Central - DLCI 50 Cloud(config-if)#encapsulation frame-relay Cloud(config-if)#clock rate 125000 Cloud(config-if)#frame-relay lmi-type cisco Cloud(config-if)#frame-relay intf-type dce Cloud(config-if)#frame-relay route 101 interface Serial1 50 Cloud(config-if)#frame-relay route 102 interface Serial2 50 Cloud(config-if)#exit Cloud(config)#interface Serial1 Cloud(config-if)#description Frame-relay connection to Branch1 - DLCI 101 Cloud(config-if)#encapsulation frame-relay Cloud(config-if)#clock rate 125000 Cloud(config-if)#frame-relay lmi-type cisco Cloud(config-if)#frame-relay intf-type dce Cloud(config-if)#frame-relay route 50 interface Serial0 101 Cloud(config-if)#exit Cloud(config)#interface Serial2 Cloud(config-if)#description Frame-relay connection to Branch2 - DLCI 102 Cloud(config-if)#encapsulation frame-relay Cloud(config-if)#clock rate 125000 Cloud(config-if)#frame-relay lmi-type cisco Cloud(config-if)#frame-relay intf-type dce Cloud(config-if)#frame-relay route 50 interface Serial0 102 Cloud(config-if)#exit Cloud(config)#end Cloud#
Discussion
This type of configuration can be extremely useful when you need to test basic Frame Relay functionality in a lab, and you don't happen to have a real Frame Relay switch available. However it's extremely important to remember that a router is not a Frame Relay switch, and it doesn't emulate all of the functionality of the switch. In particular, the router will not support switching of SVCs. Also, although Cisco has introduced the frame-relay congestion-management command, you can still only generate FECN and BECN notifications on a limited set of router hardware and software configurations. So if you are using this type of configuration to test adaptive traffic shaping or any other feature that relies on BECN notifications, it will not give you a reliable simulation of a real cloud.
To use the router as a Frame Relay switch, you must first enable the frame-relay switching option. Then you must configure each interface as DCE with the frame-relay intf-type command, and supply a clock signal with the clock rate command. Cisco routers will not allow you to configure this command unless you use a DCE cable on the interface. And, finally, you need to map the PVCs. In this case, we have configured a central hub router and two branch routers, as in Recipe 10.1. The central router can see both of the branch routers, one with DLCI 101, and the other with DLCI 102. Both of the branch routers see the central router with DLCI 50. The two branch routers cannot see one another directly.
In this example, all three of the Frame Relay connections are to DTE devices such as routers, so all of the interfaces are configured for DCE signaling. However, you can also configure connections to other switching devices. This might be useful if you were interested in constructing your own private Frame Relay cloud. In this case, you would still need to designate one of the devices to be the physical DCE and supply the clock. Then you would configure the interface type on both devices as nni:
Cloud#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Cloud(config)#interface Serial2 Cloud(config-if)#description Frame-relay connection to next switch Cloud(config-if)#encapsulation frame-relay Cloud(config-if)#clock rate 125000 Cloud(config-if)#frame-relay lmi-type cisco Cloud(config-if)#frame-relay intf-type nni Cloud(config-if)#exit Cloud(config)#end Cloud#
You would also use frame-relay route statements to configure one or more PVCs to be served by this neighboring switch. The PVC routing commands in this case are identical to those for DCE interfaces.
You can look at the routing of the virtual circuits on a router that is configured for Frame Relay switching with the show frame-relay route command:
Cloud#show frame-relay route Input Intf Input Dlci Output Intf Output Dlci Status Serial0 101 Serial1 50 active Serial0 102 Serial2 50 inactive Serial0 103 Serial3 50 inactive Serial1 50 Serial0 101 active Serial1 102 Serial2 101 inactive Serial1 103 Serial3 101 inactive Serial2 50 Serial0 102 inactive Serial2 101 Serial1 102 inactive Serial2 103 Serial3 102 inactive Serial3 50 Serial0 103 inactive Serial3 101 Serial1 103 inactive Serial3 102 Serial2 103 inactive Cloud#
This output shows, for example, that traffic received on DLCI number 101 through interface Serial0 is forwarded to DLCI number 50 on Serial1. And a few lines lower, you can see the reverse path as well. The status for both of these lines is active, so this virtual circuit is working properly.
Another extremely useful option for creating private Frame Relay networks is the ability to specify a GRE tunnel as the destination of a Frame Relay route command:
Cloud(config)#interface Loopback1 Cloud(config-if)#ip address 192.168.2.1 255.255.255.255 Cloud(config-if)#exit Cloud(config)#interface Tunnel1 Cloud(config-if)#ip address 192.168.1.5 255.255.255.252 Cloud(config-if)#tunnel source 192.168.2.1 Cloud(config-if)#tunnel destination 192.168.2.2 Cloud(config-if)#exit Cloud(config)#interface Serial1 Cloud(config-if)#frame-relay route 201 interface Tunnel1 101 Cloud(config-if)#exit
In this case, we have created a GRE tunnel interface called Tunnel1, which terminates on another router somewhere else in the network. Then we route Frame Relay DLCI 201 to this tunnel interface. On the other router, you would need to create a similar GRE tunnel interface. Then, on a Serial interface on that other router, you would put a matching frame-relay route statement:
Cloud9(config)#interface Loopback1 Cloud9(config-if)#ip address 192.168.2.2 255.255.255.255 Cloud9(config-if)#exit Cloud9(config)#interface Tunnel1 Cloud9(config-if)#ip address 192.168.1.6 255.255.255.252 Cloud9(config-if)#tunnel source 192.168.2.2 Cloud9(config-if)#tunnel destination 192.168.2.1 Cloud9(config-if)#exit Cloud9(config)#interface Serial1 Cloud9(config-if)#frame-relay route 301 interface Tunnel1 101 Cloud9(config-if)#exit
This is an extremely efficient way of creating a virtual Frame Relay cloud layered on top of an existing IP network.
See Also
Chapter 12; Recipe 10.1
Router Configuration and File Management
- Configuring the Router via TFTP
- Saving Router Configuration to Server
- Booting the Router Using a Remote Configuration File
- Storing Configuration Files Larger Than NVRAM
- Clearing the Startup Configuration
- Loading a New IOS Image
- Booting a Different IOS Image
- Booting over the Network
- Copying an IOS Image to a Server
- Copying an IOS Image Through the Console
- Deleting Files from Flash
- Partitioning Flash
- Using the Router as a TFTP Server
- Using FTP from the Router
- Generating Large Numbers of Router Configurations
- Changing the Configurations of Many Routers at Once
- Extracting Hardware Inventory Information
- Backing Up Router Configurations
- Warm Reload
- Warm Upgrade
- Configuration Archiving
- Locking Configuration Access
Router Management
- Creating Command Aliases
- Managing the Routers ARP Cache
- Tuning Router Buffers
- Auto Tuning Buffers
- Using the Cisco Discovery Protocol
- Disabling the Cisco Discovery Protocol
- Using the Small Servers
- Enabling HTTP Access to a Router
- Enabling Secure HTTP (HTTPS) Access to a Router
- Using Static Hostname Tables
- Enabling Domain Name Services
- Disabling Domain Name Lookups
- Specifying a Router Reload Time
- Scheduling of Router Commands
- Displaying Historical CPU Values
- Creating Exception Dump Files
- Generating a Report of Interface Information
- Generating a Report of Routing Table Information
- Generating a Report of ARP Table Information
- Generating a Server Host Table File
User Access and Privilege Levels
- Setting Up User IDs
- Encrypting Passwords
- Using Better Password-Encryption Techniques
- Removing Passwords from a Router Configuration File
- Deciphering Ciscos Weak Password Encryption
- Displaying Active Users
- Sending Messages to Other Users
- Changing the Number of VTYs
- Changing VTY Timeouts
- Restricting VTY Access by Protocol
- Enabling Absolute Timeouts on VTY Lines
- Implementing Banners
- Disabling Banners on a Port
- Disabling Router Lines
- Reserving a VTY Port for Administrative Access
- Restricting Inbound Telnet Access
- Logging Telnet Access
- Setting the Source Address for Telnet
- Automating the Login Sequence
- Using SSH for Secure Access
- Changing Privilege Level of IOS Commands
- Defining Per User Privileges
- Defining Per Port Privileges
TACACS+
- Authenticating Login IDs from a Central System
- Restricting Command Access
- Losing Access to the TACACS+ Server
- Disabling TACACS+ Authentication on a Particular Line
- Capturing User Keystrokes
- Logging System Events
- Setting the IP Source Address for TACACS+ Messages
- Sample Server Configuration Files
IP Routing
- Finding an IP Route
- Finding Types of IP Routes
- Converting Different Mask Formats
- Using Static Routing
- Floating Static Routes
- Using Policy-Based Routing to Route Based on Source Address
- Using Policy-Based Routing to Route Based on Application Type
- Examining Policy-Based Routing
- Changing Administrative Distances
- Routing Over Multiple Paths with Equal Costs
- Static Routes That Track Interfaces or Other Routes
- Keeping Statistics on Routing Table Changes
RIP
- Configuring RIP Version 1
- Filtering Routes with RIP
- Redistributing Static Routes into RIP
- Redistributing Routes Using Route Maps
- Creating a Default Route in RIP
- Disabling RIP on an Interface
- Default Passive Interface
- Unicast Updates for RIP
- Applying Offsets to Routes
- Adjusting Timers
- Configuring Interpacket Delay
- Enabling Nonperiodic Updates
- Increasing the RIP Input Queue
- Configuring RIP Version 2
- Enabling RIP Authentication
- RIP Route Summarization
- Route Tagging
EIGRP
- Configuring EIGRP
- Filtering Routes with EIGRP
- Redistributing Routes into EIGRP
- Redistributing Routes into EIGRP Using Route Maps
- Disabling EIGRP on an Interface
- Adjusting EIGRP Metrics
- Adjusting Timers
- Enabling EIGRP Authentication
- EIGRP Route Summarization
- Logging EIGRP Neighbor State Changes
- Limiting EIGRPs Bandwidth Utilization
- EIGRP Stub Routing
- Route Tagging
- Viewing EIGRP Status
OSPF
- Configuring OSPF
- Filtering Routes in OSPF
- Adjusting OSPF Costs
- Creating a Default Route in OSPF
- Redistributing Static Routes into OSPF
- Redistributing External Routes into OSPF
- Manipulating DR Selection
- Setting the OSPF RID
- Enabling OSPF Authentication
- Selecting the Appropriate Area Types
- Using OSPF on Dial Interfaces
- Summarizing Routes in OSPF
- Disabling OSPF on Certain Interfaces
- Changing the Network Type on an Interface
- OSPF Route Tagging
- Logging OSPF Adjacency Changes
- Adjusting OSPF Timers
- Reducing OSPF Traffic in Stable Networks
- OSPF Virtual Links
- Viewing OSPF Status with Domain Names
- Debugging OSPF
BGP
- Configuring BGP
- Using eBGP Multihop
- Adjusting the Next-Hop Attribute
- Connecting to Two ISPs
- Connecting to Two ISPs with Redundant Routers
- Restricting Networks Advertised to a BGP Peer
- Adjusting Local Preference Values
- Load-Balancing
- Removing Private ASNs from the AS Path
- Filtering BGP Routes Based on AS Paths
- Reducing the Size of the Received Routing Table
- Summarizing Outbound Routing Information
- Prepending ASNs to the AS Path
- Redistributing Routes with BGP
- Using Peer Groups
- Authenticating BGP Peers
- Using BGP Communities
- Using BGP Route Reflectors
- Putting It All Together
Frame Relay
- Setting Up Frame Relay with Point-to-Point Subinterfaces
- Adjusting LMI Options
- Setting Up Frame Relay with Map Statements
- Using Multipoint Subinterfaces
- Configuring Frame Relay SVCs
- Simulating a Frame Relay Cloud
- Compressing Frame Relay Data on a Subinterface
- Compressing Frame Relay Data with Maps
- PPP over Frame Relay
- Viewing Frame Relay Status Information
Handling Queuing and Congestion
- Fast Switching and CEF
- Setting the DSCP or TOS Field
- Using Priority Queuing
- Using Custom Queuing
- Using Custom Queues with Priority Queues
- Using Weighted Fair Queuing
- Using Class-Based Weighted Fair Queuing
- Using NBAR Classification
- Controlling Congestion with WRED
- Using RSVP
- Manual RSVP Reservations
- Aggregating RSVP Reservations
- Using Generic Traffic Shaping
- Using Frame-Relay Traffic Shaping
- Using Committed Access Rate
- Implementing Standards-Based Per-Hop Behavior
- AutoQoS
- Viewing Queue Parameters
Tunnels and VPNs
- Creating a Tunnel
- Tunneling Foreign Protocols in IP
- Tunneling with Dynamic Routing Protocols
- Viewing Tunnel Status
- Creating an Encrypted Router-to-Router VPN in a GRE Tunnel
- Creating an Encrypted VPN Between the LAN Interfaces of Two Routers
- Generating RSA Keys
- Creating a Router-to-Router VPN with RSA Keys
- Creating a VPN Between a Workstation and a Router
- Creating an SSL VPN
- Checking IPSec Protocol Status
Dial Backup
- Automating Dial Backup
- Using Dialer Interfaces
- Using an Async Modem on the AUX Port
- Using Backup Interfaces
- Using Dialer Watch
- Using Virtual Templates
- Ensuring Proper Disconnection
- View Dial Backup Status
- Debugging Dial Backup
NTP and Time
- Time-Stamping Router Logs
- Setting the Time
- Setting the Time Zone
- Adjusting for Daylight Saving Time
- Synchronizing the Time on All Routers (NTP)
- Configuring NTP Redundancy
- Setting the Router As the NTP Master for the Network
- Changing NTP Synchronization Periods
- Using NTP to Send Periodic Broadcast Time Updates
- Using NTP to Send Periodic Multicast Time Updates
- Enabling and Disabling NTP Per Interface
- NTP Authentication
- Limiting the Number of Peers
- Restricting Peers
- Setting the Clock Period
- Checking the NTP Status
- Debugging NTP
- NTP Logging
- Extended Daylight Saving Time
- NTP Server Configuration
DLSw
- Simple Bridging
- Configuring DLSw
- Using DLSw to Bridge Between Ethernet and Token Ring
- Converting Ethernet and Token Ring MAC Addresses
- Configuring SDLC
- Configuring SDLC for Multidrop Connections
- Using STUN
- Using BSTUN
- Controlling DLSw Packet Fragmentation
- Tagging DLSw Packets for QoS
- Supporting SNA Priorities
- DLSw+ Redundancy and Fault Tolerance
- Viewing DLSw Status Information
- Viewing SDLC Status Information
- Debugging DSLw
Router Interfaces and Media
- Viewing Interface Status
- Configuring Serial Interfaces
- Using an Internal T1 CSU/DSU
- Using an Internal ISDN PRI Module
- Using an Internal 56 Kbps CSU/DSU
- Configuring an Async Serial Interface
- Configuring ATM Subinterfaces
- Setting Payload Scrambling on an ATM Circuit
- Classical IP Over ATM
- Configuring Ethernet Interface Features
- Configuring Token Ring Interface Features
- Connecting VLAN Trunks with ISL
- Connecting VLAN Trunks with 802.1Q
- LPD Printer Support
Simple Network Management Protocol
- Configuring SNMP
- Extracting Router Information via SNMP Tools
- Recording Important Router Information for SNMP Access
- Using SNMP to Extract Inventory Information from a List of Routers
- Using Access Lists to Protect SNMP Access
- Logging Unauthorized SNMP Attempts
- Limiting MIB Access
- Using SNMP to Modify a Routers Running Configuration
- Using SNMP to Copy a New IOS Image
- Using SNMP to Perform Mass Configuration Changes
- Preventing Unauthorized Configuration Modifications
- Making Interface Table Numbers Permanent
- Enabling SNMP Traps and Informs
- Sending Syslog Messages As SNMP Traps and Informs
- Setting SNMP Packet Size
- Setting SNMP Queue Size
- Setting SNMP Timeout Values
- Disabling Link Up/Down Traps per Interface
- Setting the IP Source Address for SNMP Traps
- Using RMON to Send Traps
- Enabling SNMPv3
- Strong SNMPv3 Encryption
- Using SAA
Logging
- Enabling Local Router Logging
- Setting the Log Size
- Clearing the Routers Log
- Sending Log Messages to Your Screen
- Using a Remote Log Server
- Enabling Syslog on a Unix Server
- Changing the Default Log Facility
- Restricting What Log Messages Are Sent to the Server
- Setting the IP Source Address for Syslog Messages
- Logging Router Syslog Messages in Different Files
- Maintaining Syslog Files on the Server
- Testing the Syslog Sever Configuration
- Preventing the Most Common Messages from Being Logged
- Rate-Limiting Syslog Traffic
- Enabling Error Log Counting
- XML-Formatted Log Messages
- Modifying Log Messages
Access-Lists
- Filtering by Source or Destination IP Address
- Adding a Comment to an ACL
- Filtering by Application
- Filtering Based on TCP Header Flags
- Restricting TCP Session Direction
- Filtering Multiport Applications
- Filtering Based on DSCP and TOS
- Logging When an Access-List Is Used
- Logging TCP Sessions
- Analyzing ACL Log Entries
- Using Named and Reflexive Access-Lists
- Dealing with Passive Mode FTP
- Using Time-Based Access-Lists
- Filtering Based on Noncontiguous Ports
- Advanced Access-List Editing
- Filtering IPv6
DHCP
- Using IP Helper Addresses for DHCP
- Limiting the Impact of IP Helper Addresses
- Using DHCP to Dynamically Configure Router IP Addresses
- Dynamically Allocating Client IP Addresses via DHCP
- Defining DHCP Configuration Options
- Defining DHCP Lease Periods
- Allocating Static IP Addresses with DHCP
- Configuring a DHCP Database Client
- Configuring Multiple DHCP Servers per Subnet
- DHCP Static Mapping
- DHCP-Secured IP Address Assignment
- Showing DHCP Status
- Debugging DHCP
NAT
- Configuring Basic NAT Functionality
- Allocating External Addresses Dynamically
- Allocating External Addresses Statically
- Translating Some Addresses Statically and Others Dynamically
- Using Route Maps to Refine Static Translation Rules
- Translating in Both Directions Simultaneously
- Rewriting the Network Prefix
- Using NAT for Server Load Distribution
- Stateful NAT Failover
- Adjusting NAT Timers
- Changing TCP Ports for FTP
- Checking NAT Status
- Debugging NAT
First Hop Redundancy Protocols
- Configuring Basic HSRP Functionality
- Using HSRP Preempt
- Making HSRP React to Problems on Other Interfaces
- Load-Balancing with HSRP
- Redirecting ICMP with HSRP
- Manipulating HSRP Timers
- Using HSRP on Token Ring
- HSRP SNMP Support
- Increasing HSRP Security
- Showing HSRP State Information
- Debugging HSRP
- HSRP Version 2
- VRRP
- Gateway Load-Balancing Protocol
IP Multicast
- Configuring Basic Multicast Functionality with PIM-DM
- Routing Multicast Traffic with PIM-SM and BSR
- Routing Multicast Traffic with PIM-SM and Auto-RP
- Filtering PIM Neighbors
- Configuring Routing for a Low-Frequency Multicast Application
- Multicast over Frame Relay or ATM WANs
- Configuring CGMP
- Using IGMP Version 3
- Static Multicast Routes and Group Memberships
- Routing Multicast Traffic with MOSPF
- Routing Multicast Traffic with DVMRP
- DVMRP Tunnels
- Configuring Bidirectional PIM
- Controlling Multicast Scope with TTL
- Controlling Multicast Scope with Administratively Scoped Addressing
- Exchanging Multicast Routing Information with MBGP
- Using MSDP to Discover External Sources
- Configuring Anycast RP
- Converting Broadcasts to Multicasts
- Showing Multicast Status
- Debugging Multicast Routing
IP Mobility
- Local Area Mobility
- Home Agent Configuration
- Foreign Agent Configuration
- Making a Router a Mobile Node
- Reverse-Tunnel Forwarding
- Using HSRP for Home Agent Redundancy
IPv6
- Automatically Generating IPv6 Addresses for an Interface
- Manually Configuring IPv6 Addresses on an Interface
- Configuring DHCP for IPv6
- Dynamic Routing with RIP
- Modifying the Default RIP Parameters
- IPv6 Route Filtering and Metric Manipulation in RIP
- Using OSPF for IPv6
- IPv6 Route Filtering and Metric Manipulation in OSPF
- Route Redistribution
- Dynamic Routing with MBGP
- Tunneling IPv6 Through an Existing IPv4 Network
- Translating Between IPv6 and IPv4
MPLS
- Configuring a Basic MPLS P Router
- Configuring a Basic MPLS PE Router
- Configuring Basic MPLS CE Routers
- Configuring MPLS over ATM
- PE-CE Communication via RIP
- PE-CE Communication via OSPF
- PE-CE Communication via EIGRP
- PE-CE Communication via BGP
- QoS over MPLS
- MPLS Traffic Engineering with Autoroute
- Multicast Over MPLS
- Your Service Provider Doesnt Do What You Want
Security
- Using AutoSecure
- Using Context-Based Access-Lists
- Transparent Cisco IOS Firewall
- Stopping Denial of Service Attacks
- Inspecting Applications on Different Port Numbers
- Intrusion Detection and Prevention
- Login Password Retry Lockout
- Authentication Proxy
Appendix 1. External Software Packages
Appendix 2. IP Precedence, TOS, and DSCP Classifications
- IP Precedence, TOS, and DSCP Classifications
- Queueing Algorithms
- Dropping Packets and Congestion Avoidance
Index
EAN: 2147483647
Pages: 505
