Using Virtual Templates
Problem
You want to configure dial backup by using virtual templates.
Solution
Virtual templates provide another way of configuring a central dialup host router:
dialhost#configure terminal Enter configuration commands, one per line. End with CNTL/Z. dialhost(config)#username Router1 password dialpassword dialhost(config)#interface BRI0/0 dialhost(config-if)#no ip address dialhost(config-if)#encapsulation ppp dialhost(config-if)#dialer pool-member 1 dialhost(config-if)#isdn switch-type basic-ni dialhost(config-if)#isdn point-to-point-setup dialhost(config-if)#isdn spid1 800555123400 5551234 dialhost(config-if)#isdn spid2 800555123500 5551235 dialhost(config-if)#ppp authentication chap dialhost(config-if)#ppp multilink dialhost(config-if)#exit dialhost(config)#interface Dialer1 dialhost(config-if)#no ip address dialhost(config-if)#encapsulation ppp dialhost(config-if)#dialer idle-timeout 300 dialhost(config-if)#dialer-group 1 dialhost(config-if)#no peer default ip address dialhost(config-if)#ppp authentication chap dialhost(config-if)#ppp multilink dialhost(config-if)#exit dialhost(config)#access-list 101 deny eigrp any any dialhost(config)#access-list 101 permit ip any any dialhost(config)#dialer-list 1 protocol ip list 101 dialhost(config)#router eigrp 55 dialhost(config-router)#network 10.0.0.0 dialhost(config-router)#exit dialhost(config)#interface Loopback1 dialhost(config-if)#ip address 10.1.99.1 255.255.255.0 dialhost(config-if)#exit dialhost(config)#interface Virtual-Template1 dialhost(config-if)#ip unnumbered Loopback1 dialhost(config-if)#encapsulation ppp dialhost(config-if)#ppp authentication chap dialhost(config-if)#ppp multilink dialhost(config-if)#ppp multilink load-threshold 50 either dialhost(config-if)#exit dialhost(config)#virtual-profile virtual-template 1 dialhost(config)#end dialhost#
Discussion
Virtual templates allow you to dynamically create virtual interfaces for dial purposes as they are required. This is only a benefit on routers that need to support several simultaneous connections, particularly when these connections are spread across several physical interfaces. So the ideal situation for using this configuration is a central dialup host router for a large enterprise WAN. Virtual templates are also useful in networks where large numbers of remote users dial in for access, such as in Internet Service Provider (ISP) networks.
Virtual templates are also useful in Frame Relay and ATM networks, where you can configure dynamic Switched Virtual Circuit (SVC) connections. And you can also use virtual templates for Permanent Virtual Circuit (PVC) connections when you need to use a nonstandard Layer 2 encapsulation such as PPP. We discuss these scenarios further in Chapters 10 and 16.
Compare this recipe to Recipe 13.2, where we first introduced the idea of a dialer interface to support multiple connections. In this case, our physical interface is an ISDN BRI, rather than a PRI, but in either case you could use one or several interfaces of any type that supports dialing. The first difference you should notice is that we have not configured an IP address on the Dialer interface:
dialhost(config)#interface Dialer1 dialhost(config-if)#no ip address
This is because we intend to dynamically generate virtual interfaces, which will hold the IP address information. In fact, we have created a new Loopback interface to carry the IP address for all of these virtual interfaces:
dialhost(config)#interface Loopback1 dialhost(config-if)#ip address 10.1.99.1 255.255.255.0 dialhost(config-if)#exit dialhost(config)#interface Virtual-Template1 dialhost(config-if)#ip unnumbered Loopback1 dialhost(config-if)#encapsulation ppp dialhost(config-if)#ppp authentication chap dialhost(config-if)#ppp multilink dialhost(config-if)#ppp multilink load-threshold 50 either dialhost(config-if)#exit
The configuration of the Virtual-Template interface includes all of the relevant PPP and IP information, including configuration for PPP multilink. The router will clone this Virtual-Template to create new virtual access interfaces as it needs them. Some of these virtual accesses may use PPP multilink so span several physical interfaces, so we need to include this configuration here.
Then we need to use the virtual-profile command to allow the router to use this template whenever it needs to dynamically create interfaces:
dialhost(config)#virtual-profile virtual-template 1
The final argument to this command, 1, specifies the Virtual-Template1 interface configuration.
This router can now dynamically create virtual access interfaces as it requires them. Look at the output of the show ip interface brief command when there are no calls connected:
dialhost#show ip interface brief Interface IP-Address OK? Method Status Protocol FastEthernet0/0 192.168.5.12 YES NVRAM up up Serial0/0 unassigned YES NVRAM administratively down down BRI0/0 unassigned YES NVRAM up up BRI0/0:1 unassigned YES unset down down BRI0/0:2 unassigned YES unset down down Virtual-Access1 unassigned YES unset down down Virtual-Template1 10.1.99.1 YES TFTP down down Dialer1 unassigned YES NVRAM up up Loopback0 192.168.57.12 YES NVRAM up up Loopback1 10.1.99.1 YES NVRAM up up dialhost#
After we bring up remote dial connection, you can see that the router has dynamically generated a new interface called Virtual-Access2:
dialhost#show ip interface brief Interface IP-Address OK? Method Status Protocol FastEthernet0/0 192.168.5.12 YES NVRAM up up Serial0/0 unassigned YES NVRAM administratively down down BRI0/0 unassigned YES NVRAM up up BRI0/0:1 unassigned YES unset up up BRI0/0:2 unassigned YES unset down down Virtual-Access1 unassigned YES unset down down Virtual-Template1 10.1.99.1 YES TFTP down down Virtual-Access2 10.1.99.1 YES TFTP up up Dialer1 unassigned YES NVRAM up up Loopback0 192.168.57.12 YES NVRAM up up Loopback1 10.1.99.1 YES NVRAM up up dialhost#
You can use the show vtemplate command to get additional information and statistics on your virtual templates:
dialhost#show vtemplate Virtual access subinterface creation is globally enabled Active Active Subint Pre-clone Pre-clone Interface Interface Subinterface Capable Available Limit Type --------- ------------ ------- --------- --------- --------- Vt1 1 0 Yes -- -- Serial Usage Summary Interface Subinterface --------- ------------ Current Serial in use 2 0 Current Serial free 1 1 Current Ether in use 0 0 Current Ether free 0 0 Current Tunnel in use 0 0 Current Tunnel free 0 0 Total 3 1 Cumulative created 6 8 Cumulative freed 3 8 Base virtual access interfaces: 1 Total create or clone requests: 4 Cancelled create or clone requests: 0 Current request queue size: 0 Current free pending: 0 Current recycle pending: 0 Maximum request duration: 8 msec Average request duration: 4 msec Last request duration: 8 msec Maximum processing duration: 8 msec Average processing duration: 4 msec Last processing duration: 8 msec dialhost#
This output shows that there is currently one virtual template clone in use, and that the router has created such cloned interfaces four times since it last booted. The structure of this output varies drastically, depending on which IOS version and feature set you have installed in your router. The above example shows a Version 12.4 IP Base image.
See Also
Chapters 10 and 16; Recipe 13.2
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
Cisco IOS Cookbook (Cookbooks (OReilly))
ISBN: 0596527225
EAN: 2147483647
EAN: 2147483647
Year: 2004
Pages: 505
Pages: 505
Authors: Kevin Dooley, Ian Brown
