Configuring Ethernet Interfaces

This module describes the configuration of Ethernet interfaces.

The following distributed ethernet architecture delivers network scalability and performance, while enabling service providers to offer high-density, high-bandwidth networking solutions.

  • 100-Megabit

  • 1-Gigabit

  • 100-Gigabit

These solutions are designed to interconnect the router with other systems in POPs, including core and edge routers and Layer 2 and Layer 3 switches.

Restrictions

Router does not support configuration of the static mac address.

Configuring Gigabit Ethernet Interfaces

Use this procedure to create a basic Ethernet interface configuration.

SUMMARY STEPS

  1. show version
  2. show interfaces [GigE TenGigE HundredGigE] interface-path-id
  3. configure
  4. interface [GigE TenGigE HundredGigE] interface-path-id
  5. ipv4 address ip-address mask
  6. flow-control {bidirectional| egress | ingress}
  7. mtu bytes
  8. negotiation auto
  9. no shutdown
  10. end or commit
  11. show interfaces [GigE TenGigE HundredGigE ] interface-path-id

DETAILED STEPS

Step 1

show version

Example:


RP/0/RP0/CPU0:router# show version

(Optional) Displays the current software version, and can also be used to confirm that the router recognizes the line card.

Step 2

show interfaces [GigE TenGigE HundredGigE] interface-path-id

Example:


RP/0/RP0/CPU0:router# show interface HundredGigE 0/1/0/1

(Optional) Displays the configured interface and checks the status of each interface port.

Step 3

configure

Example:


RP/0/RP0/CPU0:router# configure terminal

Enters global configuration mode.

Step 4

interface [GigE TenGigE HundredGigE] interface-path-id

Example:


RP/0/RP0/CPU0:router(config)# interface HundredGigE 0/1/0/1

Enters interface configuration mode and specifies the Ethernet interface name and notation rack/slot/module/port. Possible interface types for this procedure are:

  • GigE

  • 10GigE

  • 100GigE

    Note 

    • The example indicates a 100-Gigabit Ethernet interface in the line card in slot 1.

Step 5

ipv4 address ip-address mask

Example:


RP/0/RP0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224

Assigns an IP address and subnet mask to the interface.

  • Replace ip-address with the primary IPv4 address for the interface.

  • Replace mask with the mask for the associated IP subnet. The network mask can be specified in either of two ways:

  • The network mask can be a four-part dotted decimal address. For example, 255.0.0.0 indicates that each bit equal to 1 means that the corresponding address bit belongs to the network address.

  • The network mask can be indicated as a slash (/) and number. For example, /8 indicates that the first 8 bits of the mask are ones, and the corresponding bits of the address are network address.

Step 6

flow-control {bidirectional| egress | ingress}

Example:


RP/0/RP0/CPU0:router(config-if)# flow control ingress

(Optional) Enables the sending and processing of flow control pause frames.

  • egress —Enables the sending of flow control pause frames in egress.

  • ingress —Enables the processing of received pause frames on ingress.

  • bidirectional —Enables the sending of flow control pause frames in egress and the processing of received pause frames on ingress.

Step 7

mtu bytes

Example:


RP/0/RP0/CPU0:router(config-if)# mtu 1448

(Optional) Sets the MTU value for the interface.

  • The default is 1514 bytes for normal frames and 1518 bytes for 802.1Q tagged frames.

  • The range for 100-Gigabit Ethernet mtu values is 64 bytes to 65535 bytes.

Step 8

negotiation auto

Example:


RP/0/RP0/CPU0:router(config-if)# negotiation auto

(Optional) Enables autonegotiation on a Gigabit Ethernet interface.

  • Autonegotiation must be explicitly enabled on both ends of the connection, or speed and duplex settings must be configured manually on both ends of the connection.

  • If autonegotiation is enabled, any speed or duplex settings that you configure manually take precedence.

    Note 

    • The negotiation auto command is available on Gigabit Ethernet interfaces only.

Step 9

no shutdown

Example:


RP/0/RP0/CPU0:router(config-if)# no shutdown

Removes the shutdown configuration, which forces an interface administratively down.

Step 10

end or commit

Example:


RP/0/RP0/CPU0:router(config-if)# end

or 


RP/0/RP0/CPU0:router(config-if)# commit

Saves configuration changes.

  • When you issue the end command, the system prompts you to commit changes: 

    
Uncommitted changes found, commit them before exiting(yes/no/cancel)?
[cancel]:

  • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

  • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

  • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

Step 11

show interfaces [GigE TenGigE HundredGigE ] interface-path-id

Example:


RP/0/RP0/CPU0:router# show interfaces HundredGigE 0/1/0/1

(Optional) Displays statistics for interfaces on the router.

Example

This example shows how to configure an interface for a 100-Gigabit Ethernet line card: 


RP/0/RP0/CPU0:router# configure 
RP/0/RP0/CPU0:router(config)# interface HundredGigE 0/1/0/1 
RP/0/RP0/CPU0:router(config-if)# ipv4 address 172.18.189.38 255.255.255.224 
RP/0/RP0/CPU0:router(config-if)# flow-control ingress 
RP/0/RP0/CPU0:router(config-if)# mtu 1448 

RP/0/RP0/CPU0:router(config-if)# no shutdown 
RP/0/RP0/CPU0:router(config-if)# end 
Uncommitted changes found, commit them? [yes]: yes 


RP/0/RP0/CPU0:router# show interfaces HundredGigE 0/5/0/24 
HundredGigE0/5/0/24 is up, line protocol is up
  Interface state transitions: 1
  Hardware is HundredGigE, address is 6219.8864.e330 (bia 6219.8864.e330)
  Internet address is 3.24.1.1/24
  MTU 9216 bytes, BW 100000000 Kbit (Max: 100000000 Kbit)
     reliability 255/255, txload 3/255, rxload 3/255
  Encapsulation ARPA,
  Full-duplex, 100000Mb/s, link type is force-up
  output flow control is off, input flow control is off
  Carrier delay (up) is 10 msec
  loopback not set,
  Last link flapped 10:05:07
  ARP type ARPA, ARP timeout 04:00:00
  Last input 00:08:56, output 00:00:00
  Last clearing of "show interface" counters never
  5 minute input rate 1258567000 bits/sec, 1484160 packets/sec
  5 minute output rate 1258584000 bits/sec, 1484160 packets/sec
     228290765840 packets input, 27293508436038 bytes, 0 total input drops
     0 drops for unrecognized upper-level protocol
     Received 15 broadcast packets, 45 multicast packets
              0 runts, 0 giants, 0 throttles, 0 parity
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     212467849449 packets output, 25733664696650 bytes, 0 total output drops
     Output 23 broadcast packets, 15732 multicast packets
     39 output errors, 0 underruns, 0 applique, 0 resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions

RP/0/RP0/CPU0:router# show running-config interface HundredGigE 0/5/0/24 

interface HundredGigE 0/5/0/24
 mtu 9216
 service-policy input linerate
 service-policy output elinerate
 ipv4 address 3.24.1.1 255.255.255.0
 ipv6 address 3:24:1::1/64
 flow ipv4 monitor perfv4 sampler fsm ingress
!

Information About Configuring Ethernet

This section provides the following information sections:

Default Configuration Values for 100-Gigabit Ethernet

This table describes the default interface configuration parameters that are present when an interface is enabled on a 10-Gigabit Ethernet or 100-Gigabit Ethernet line card.


Note

You must use the shutdown command to bring an interface administratively down. The interface default is no shutdown . When a line card is first inserted into the router, if there is no established preconfiguration for it, the configuration manager adds a shutdown item to its configuration. This shutdown can be removed only be entering the no shutdown command.

Table 1. 100-Gigabit Ethernet Line Card Default Configuration Values

Parameter

Configuration File Entry

Default Value

Flow control

flow-control

egress on
ingress off

MTU

mtu

  • 1514 bytes for normal frames

  • 1518 bytes for 802.1Q tagged frames.

  • 1522 bytes for Q-in-Q frames.

MAC address

mac address

Hardware burned-in address (BIA)

Ethernet MTU

The Ethernet maximum transmission unit (MTU) is the size of the largest frame, minus the 4-byte frame check sequence (FCS), that can be transmitted on the Ethernet network. Every physical network along the destination of a packet can have a different MTU.

Cisco IOS XR software supports two types of frame forwarding processes:

  • Fragmentation for IPV4 packets–In this process, IPv4 packets are fragmented as necessary to fit within the MTU of the next-hop physical network.


    Note

    IPv6 does not support fragmentation.

  • MTU discovery process determines largest packet size–This process is available for all IPV6 devices, and for originating IPv4 devices. In this process, the originating IP device determines the size of the largest IPv6 or IPV4 packet that can be sent without being fragmented. The largest packet is equal to the smallest MTU of any network between the IP source and the IP destination devices. If a packet is larger than the smallest MTU of all the networks in its path, that packet will be fragmented as necessary. This process ensures that the originating device does not send an IP packet that is too large.

Jumbo frame support is automatically enable for frames that exceed the standard frame size. The default value is 1514 for standard frames and 1518 for 802.1Q tagged frames. These numbers exclude the 4-byte frame check sequence (FCS).

802.1Q VLAN

A VLAN is a group of devices on one or more LANs that are configured so that they can communicate as if they were attached to the same wire, when in fact they are located on a number of different LAN segments. Because VLANs are based on logical instead of physical connections, it is very flexible for user and host management, bandwidth allocation, and resource optimization.

The IEEE's 802.1Q protocol standard addresses the problem of breaking large networks into smaller parts so broadcast and multicast traffic does not consume more bandwidth than necessary. The standard also helps provide a higher level of security between segments of internal networks.

The 802.1Q specification establishes a standard method for inserting VLAN membership information into Ethernet frames.

VRRP

The Virtual Router Redundancy Protocol (VRRP) eliminates the single point of failure inherent in the static default routed environment. VRRP specifies an election protocol that dynamically assigns responsibility for a virtual router to one of the VPN concentrators on a LAN. The VRRP VPN concentrator controlling the IP addresses associated with a virtual router is called the master, and forwards packets sent to those IP addresses. When the master becomes unavailable, a backup VPN concentrator takes the place of the master.

HSRP

Hot Standby Routing Protocol (HSRP) is a proprietary protocol from Cisco. HSRP is a routing protocol that provides backup to a router in the event of failure. Several routers are connected to the same segment of an Ethernet, FDDI, or token-ring network and work together to present the appearance of a single virtual router on the LAN. The routers share the same IP and MAC addresses and therefore, in the event of failure of one router, the hosts on the LAN are able to continue forwarding packets to a consistent IP and MAC address. The transfer of routing responsibilities from one device to another is transparent to the user.

HSRP is designed to support non disruptive switchover of IP traffic in certain circumstances and to allow hosts to appear to use a single router and to maintain connectivity even if the actual first hop router they are using fails. In other words, HSRP protects against the failure of the first hop router when the source host cannot learn the IP address of the first hop router dynamically. Multiple routers participate in HSRP and in concert create the illusion of a single virtual router. HSRP ensures that one and only one of the routers is forwarding packets on behalf of the virtual router. End hosts forward their packets to the virtual router.

The router forwarding packets is known as the active router. A standby router is selected to replace the active router should it fail. HSRP provides a mechanism for determining active and standby routers, using the IP addresses on the participating routers. If an active router fails a standby router can take over without a major interruption in the host's connectivity.

HSRP runs on top of User Datagram Protocol (UDP), and uses port number 1985. Routers use their actual IP address as the source address for protocol packets, not the virtual IP address, so that the HSRP routers can identify each other.

Subinterfaces

In Cisco IOS XR Software, interfaces are, by default, main interfaces. A main interface is also called a trunk interface, which is not to be confused with the usage of the word trunk in the context of VLAN trunking.

There are three types of trunk interfaces:

  • Physical

  • Bundle

The physical interfaces are automatically created when the router recognizes a card and its physical interfaces. However, bundle interfaces are not automatically created. They are created when they are configured by the user.

The following configuration samples are examples of trunk interfaces being created:

  • interface HundredGigabitethernet 0/5/0/0

  • interface bundle-ether 1

A subinterface is a logical interface that is created under a trunk interface.

To create a subinterface, the user must first identify a trunk interface under which to place it. In the case of bundle interfaces, if one does not already exist, a bundle interface must be created before any subinterfaces can be created under it.

The user then assigns a subinterface number to the subinterface to be created. The subinterface number must be a positive integer from zero to some high value. For a given trunk interface, each subinterface under it must have a unique value.

Subinterface numbers do not need to be contiguous or in numeric order. For example, the following subinterfaces numbers would be valid under one trunk interface:

1001, 0, 97, 96, 100000

Subinterfaces can never have the same subinterface number under one trunk.

In the following example, the card in slot 5 has trunk interface, HundredGigE 0/5/0/0. A subinterface, HundredGigE 0/5/0/0.0, is created under it. 


RP/0/RP0/CPU0:router#  conf
Mon Sep 21 11:12:11.722 EDT
RP/0/RP0/CPU0:router(config)#  interface HundredGigE 0/5/0/0.0
RP/0/RP0/CPU0:router(config-subif)# encapsulation dot1q 100
RP/0/RP0/CPU0:router(config-subif)# commit

RP/0/RP0/CPU0:Sep 21 11:12:34.819 : config[65794]: %MGBL-CONFIG-6-DB_COMMIT : Configuration committed by user 'root'. Use 'show configuration commit changes 1000000152' to view the changes.

RP/0/RP0/CPU0:router(config-subif)# end

RP/0/RP0/CPU0:Sep 21 11:12:35.633 : config[65794]: %MGBL-SYS-5-CONFIG_I : Configured from console by root
RP/0/RP0/CPU0:router#

The show run command displays the trunk interface first, then the subinterfaces in ascending numerical order. 


RP/0/RP0/CPU0:router# show run | begin HundredGigE 0/5/0/0
Mon Sep 21 11:15:42.654 EDT
Building configuration...
interface GigabitEthernet0/5/0/0
 shutdown
!
interface GigabitEthernet0/5/0/0.0
 encapsulation dot1q 100
!
interface GigabitEthernet0/5/0/1
 shutdown
!

When a subinterface is first created, the router recognizes it as an interface that, with few exceptions, is interchangeable with a trunk interface. After the new subinterface is configured further, the show interface command can display it along with its unique counters:

The following example shows the display output for the trunk interface, HundredGigE 0/5/0/0, followed by the display output for the subinterface HundredGigE 0/5/0/0.0. 


RP/0/RP0/CPU0:router# show interface HundredGigE 0/5/0/0
Mon Sep 21 11:12:51.068 EDT
GigabitEthernet0/5/0/0 is administratively down, line protocol is administratively down.
  Interface state transitions: 0
  Hardware is GigabitEthernet, address is 0024.f71b.0ca8 (bia 0024.f71b.0ca8)
  Internet address is Unknown
  MTU 1514 bytes, BW 1000000 Kbit
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation 802.1Q Virtual LAN,
  Full-duplex, 1000Mb/s, SXFD, link type is force-up
  output flow control is off, input flow control is off
  loopback not set,
  ARP type ARPA, ARP timeout 04:00:00
  Last input never, output never
  Last clearing of "show interface" counters never
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 total input drops
     0 drops for unrecognized upper-level protocol
     Received 0 broadcast packets, 0 multicast packets
              0 runts, 0 giants, 0 throttles, 0 parity
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     0 packets output, 0 bytes, 0 total output drops
     Output 0 broadcast packets, 0 multicast packets
     0 output errors, 0 underruns, 0 applique, 0 resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions


RP/0/RP0/CPU0:router# show interface HundredGigE 0/5/0/0.0
Mon Sep 21 11:12:55.657 EDT
GigabitEthernet0/5/0/0.0 is administratively down, line protocol is administratively down.
  Interface state transitions: 0
  Hardware is VLAN sub-interface(s), address is 0024.f71b.0ca8
  Internet address is Unknown
  MTU 1518 bytes, BW 1000000 Kbit
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation 802.1Q Virtual LAN, VLAN Id 100,  loopback not set,
  ARP type ARPA, ARP timeout 04:00:00
  Last input never, output never
  Last clearing of "show interface" counters never
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 total input drops
     0 drops for unrecognized upper-level protocol
     Received 0 broadcast packets, 0 multicast packets
     0 packets output, 0 bytes, 0 total output drops
     Output 0 broadcast packets, 0 multicast packets

This example shows two interfaces being created at the same time: first, the bundle trunk interface, then a subinterface attached to the trunk: 


RP/0/RP0/CPU0:router# conf
Mon Sep 21 10:57:31.736 EDT
RP/0/RP0/CPU0:router(config)# interface Bundle-Ether1
RP/0/RP0/CPU0:router(config-if)# no shut
RP/0/RP0/CPU0:router(config-if)# interface bundle-Ether1.0
RP/0/RP0/CPU0:router(config-subif)# encapsulation dot1q 100
RP/0/RP0/CPU0:router(config-subif)# commit
RP/0/RP0/CPU0:Sep 21 10:58:15.305 : config[65794]: %MGBL-CONFIG-6-DB_COMMIT : C
onfiguration committed by user 'root'. Use 'show configuration commit changes 10
00000149' to view the changes.
RP/0/RP0/CPU0:router# show run | begin Bundle-Ether1
Mon Sep 21 10:59:31.317 EDT
Building configuration..
interface Bundle-Ether1
!
interface Bundle-Ether1.0
 encapsulation dot1q 100
!

You delete a subinterface using the no interface command. 


RP/0/RP0/CPU0:router#
RP/0/RP0/CPU0:router# show run | begin HundredGigE0/5/0/0
Mon Sep 21 11:42:27.100 EDT
Building configuration...
interface GigabitEthernet0/5/0/0
 negotiation auto
!
interface HundredGigE0/5/0/0.0
 encapsulation dot1q 100
!
interface HundredGigE0/5/0/1
 shutdown
!
RP/0/RSP0/CPU0:router# conf
Mon Sep 21 11:42:32.374 EDT
RP/0/RP0/CPU0:router(config)# no interface GigabitEthernet0/5/0/0.0
RP/0/RP0/CPU0:router(config)# commit
RP/0/RP0/CPU0:Sep 21 11:42:47.237 : config[65794]: %MGBL-CONFIG-6-DB_COMMIT : Configuration committed by user 'root'. Use 'show configuration commit changes 1000000159' to view the changes.
RP/0/RP0/CPU0:router(config)# end
RP/0/RP0/CPU0:Sep 21 11:42:50.278 : config[65794]: %MGBL-SYS-5-CONFIG_I : Configured from console by root
RP/0/RP0/CPU0:router# show run | begin GigabitEthernet0/5/0/0
Mon Sep 21 11:42:57.262 EDT
Building configuration...
interface HundredGigE0/5/0/0
 negotiation auto
!
interface HundredGigE0/5/0/1
 shutdown
!