Using the Management Ethernet Interface

The Cisco C84xx Series Platform have one Gigabit Ethernet Management Ethernet interface.

Gigabit ethernet management interface

The purpose of this interface is to allow users to perform management tasks on the router; it is basically an interface that should not and often cannot forward network traffic but can otherwise access the router, often via Telnet and SSH, and perform most management tasks on the router. The interface is most useful before a router has begun routing, or in troubleshooting scenarios when the SPA interfaces are inactive.

The following aspects of the Management Ethernet interface should be noted:

  • IPv4, IPv6, and ARP are the only routed protocols supported for the interface.

  • The Ethernet Management Interface cannot be used as a Lawful Intercept MD source interface.

  • The Management Ethernet interface is part of its own VRF. This is discussed in more detail in the Gigabit ethernet management interface VRF

    .

Gigabit ethernet port numbering

The Gigabit Ethernet Management port is always GigabitEthernet0.

The port can be accessed in configuration mode like any other port on the Cisco C8400 Series Secure Router:


Router#config t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#interface gigabitethernet0
Router(config-if)#

IP address handling in ROMmon and the management ethernet port

IP addresses can be configured in ROMmon (the IP_ADDRESS= and IP_SUBNET_MASK= commands) and through the use of the IOS command-line interface (the ip address command in interface configuration mode).

Assuming the IOS process has not begun running , the IP address that was set in ROMmon acts as the IP address of the Management Ethernet interface. In cases where the IOS process is running and has taken control of the Management Ethernet interface, the IP address specified when configuring the Gigabit Ethernet 0 interface in the IOS CLI becomes the IP address of the Management Ethernet interface. The ROMmon-defined IP address is only used as the interface address when the IOS process is inactive.

For this reason, the IP addresses specified in ROMmon and in the IOS CLI can be identical and the Management Ethernet interface will function properly in single RP configurations.

Gigabit ethernet management interface VRF

The Gigabit Ethernet Management interface is automatically part of its own VRF. This VRF, which is named “Mgmt-intf,” is automatically configured and is dedicated to the Management Ethernet interface; no other interfaces can join this VRF. Therefore, this VRF does not participate in the MPLS VPN VRF or any other network-wide VRF. The Mgmt-intf VRF supports loopback interface.

Placing the management ethernet interface in its own VRF has the following effects on the Management Ethernet interface:

  • Many features must be configured or used inside the VRF, so the CLI may be different for certain management ethernet functions than on management ethernet interfaces on other routers.

  • Prevents transit traffic from traversing the router. Because all built-in portd and the Management Ethernet interface are automatically in different VRFs, no transit traffic can enter the Management Ethernet interface and leave a built-in port, or vice versa.

  • Improved security of the interface. Because the Mgmt-intf VRF has its own routing table as a result of being in its own VRF, routes can only be added to the routing table of the Management Ethernet interface if explicitly entered by a user.

The Management Ethernet interface VRF supports both IPv4 and IPv6 address families.

Common ethernet management tasks

Because users can perform most tasks on a router through the Management Ethernet interface, many tasks can be done by accessing the router through the Management Ethernet interface.

This list is not intended as a comprehensive list of all tasks that can be done using the Management Ethernet interface.

This section covers the following processes:

View the VRF configuration

The VRF configuration for the Management Ethernet interface is viewable using the show running-config vrf command.

This example shows the default VRF configuration: 


Router# show running-config vrf
Building configuration...
Current configuration : 351 bytes
vrf definition Mgmt-intf
 !
 address-family ipv4
 exit-address-family
 !
 address-family ipv6
 exit-address-family
!
(some output removed for brevity)

View VRF information for the management ethernet VRF

To see detailed information about the Management Ethernet VRF, enter the show vrf detail Mgmt-intf command: 


Router# show vrf detail Mgmt-intf

Set a default route in the management ethernet interface VRF

To set a default route in the Management Ethernet Interface VRF, enter the following command

ip route vrf Mgmt-intf 0.0.0.0 0.0.0.0 next-hop-IP-address

Set the management ethernet IP address

The IP address of the Management Ethernet port is set like the IP address on any other interface.

Below are two simple examples of configuring an IPv4 adress and an IPv6 address on the Management Ethernet interface.

IPv4 Example


Router(config)# interface GigabitEthernet 0 
Router(config-if)# ip address
 A.B.C.D A.B.C.D

IPv6 Example


Router(config)# interface GigabitEthernet 0

Router(config-if)# ipv6 address X:X:X:X::X

Telnetting over the Management Ethernet Interface

Telnetting can be done through the VRF using the Management Ethernet interface.

In the following example, the router telnets to 172.17.1.1 through the Management Ethernet interface VRF: 


Router# telnet 172.17.1.1 /vrf Mgmt-intf

Pinging over the management ethernet interface

Pinging other interfaces using the Management Ethernet interface is done through the VRF.

In the following example, the router pings the interface with the IP address of 172.17.1.1 through the Management Ethernet interface: 


Router# ping vrf Mgmt-intf 172.17.1.1
                                                                                
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.17.1.1, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/1 ms

Copy using TFTP or FTP

To copy a file using TFTP through the Management Ethernet interface, the ip tftp source-interface GigabitEthernet 0 command must be entered before entering the copy tftp command because the copy tftp command has no option of specifying a VRF name.

Similarly, to copy a file using FTP through the Management Ethernet interface, the ip ftp source-interface GigabitEthernet 0 command must be entered before entering the copy ftp command because the copy ftp command has no option of specifying a VRF name.

TFTP Example


Router(config)# ip tftp source-interface gigabitethernet 0

FTP Example


Router(config)# ip ftp source-interface gigabitethernet 0

NTP Server

To allow the software clock to be synchronized by a Network Time Protocol (NTP) time server over the Management Ethernet interface, enter the ntp server vrf Mgmt-intf command and specify the IP address of the device providing the update.

The following CLI provides an example of this procedure. 


Router(config)# ntp server vrf Mgmt-intf 172.17.1.1

SYSLOG server

To specify the Management Ethernet interface as the source IP or IPv6 address for logging purposes, enter the logging host <ip-address> vrf Mgmt-intf command.

The following CLI provides an example of this procedure. 


Router(config)# logging host <ip-address> vrf Mgmt-intf

SNMP-related services

To specify the Management Ethernet interface as the source of all SNMP trap messages, enter the snmp-server source-interface traps gigabitEthernet 0 command.

The following CLI provides an example of this procedure: 


Router(config)# snmp-server source-interface traps gigabitEthernet 0

Domain name assignment

The IP domain name assignment for the Management Ethernet interface is done through the VRF.

To define the default domain name as the Management Ethernet VRF interface, enter the ip domain-name vrf Mgmt-intf domain command. 


Router(config)# ip domain-name vrf Mgmt-intf cisco.com

DNS service

To specify the Management Ethernet interface VRF as a name server, enter the ip name-server vrf Mgmt-intf IPv4-or-IPv6-address command. 


Router(config)# ip name-server vrf Mgmt-intf
 IPv4-or-IPv6-address

RADIUS or TACACS+ Server

To group the Management VRF as part of a AAA server group, enter the ip vrf forward Mgmt-intf command when configuring the AAA server group.

The same concept is true for configuring a TACACS+ server group. To group the Management VRF as part of a TACACS+ server group, enter the ip vrf forwarding Mgmt-intf command when configuring the TACACS+ server group.

RADIUS Server Group Configuration


Router(config)# aaa group server radius hello
Router(config-sg-radius)# ip vrf forwarding Mgmt-intf

TACACS+ Server Group Example


outer(config)# aaa group server tacacs+ hello
Router(config-sg-tacacs+)# ip vrf forwarding Mgmt-intf

VTY lines with ACL

To ensure an access control list (ACL) is attached to vty lines that are and are not using VRF, use the vrf-also option when attaching the ACL to the vty lines. 


Router(config)# line vty 0 4
Router(config-line)# access-class 90 in vrf-also