Instant Access (IA)

note.gif

Noteblank.gif For complete syntax and usage information for the commands used in this chapter, see these publications:

http://www.cisco.com/en/US/products/ps11846/prod_command_reference_list.html

  • Cisco IOS Release 15.4SY supports only Ethernet interfaces. Cisco IOS Release 15.4SY does not support any WAN features or commands.


 

Prerequisites for Instant Access

See this publication for more information:

http://www.cisco.com/en/US/prod/collateral/switches/ps10902/ps715/ps13198/data_sheet_c78-728230.html

  • See this publication for more information about Instant Access:

http://www.cisco.com/en/US/prod/collateral/switches/ps10902/ps715/ps13198/white_paper_c11-728265.html

  • For image download during ISSU upgrade, remove ip tftp source-interface config on IA Parent, and add a static route to copy the image through mgmt interface.

Restrictions for Instant Access

  • The IA parent must operate in VSS mode.
note.gif

Noteblank.gif • You can enable VSS mode on a single chassis to support IA clients.
• The VSS Quad-Sup SSO (VS4O) feature is supported with IA clients from Release 15.1(2)SY2.


  • The IA parent-client connection is supported on links between WS-X6904-40G-2T, C6800-32P10G/XL, C6800-16P10G/XL, and C6800-8P10G/XL switching modules 1/10GE ports and Catalyst 6800ia access switches 10GE ports.

blank.gif You can use up to 8 IA client 10GE ports in the IA parent-client link. See this document for information about the port configuration for WS-X6904-40G-2T, C6800-32P10G/XL, C6800-16P10G/XL, and C6800-8P10G/XL switching modules:

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/white_paper_c11-696669.html

blank.gif IA client 10-Gigabit Ethernet ports require no configuration.

blank.gif UDLD, LLDP, and CDP are not supported on the IA parent-client link.

blank.gif IA does not use STP on the IA parent-client connection.

blank.gif Use only XL based modules for scale FEX QoS configuration to prevent issues with TCAM (ternary content-addressable memory) utilization. When QoS policy is configured on 1500 FEX host ports, the first 511 interfaces share the TCAM utilization. But, remaining ports will start using new TCAM entries for each interface and will exhaust non-XL TCAM utilization.

  • IA client maximum values:
  • Value Description:
    Maximum Value

    Maximum IA client ports

    2016 ports across 42 Catalyst 6800ia access switches

    note.gif

    Noteblank.gif The Supervisor Engine 2T module can support only up to 1200 FEX host ports with 15.2(1)SY and 15.2(1)SY0a and up to 1536 FEX host ports with 15.2(1)SY1 and later.


    Maximum IA client stacks

    42 (defined by IA client FEX number 1–42 range.)

    note.gif

    Noteblank.gif The Supervisor Engine 2T module can support only up to 25 IA client switches with 15.2(1)SY and 15.2(1)SY0a and up to 32 IA client switches with 15.2(1)SY1 and later. The Supervisor Engine 2T module can support up to 42 Cat3560CX switches as IA client.


    Maximum Catalyst 6800ia access switches per IA client stack

    5

    • An IA client stack acts as single switch unit.
    • Instant access only supports connection with stacking cables to form a stack.
    • With an IA client that has multiple Catalyst 6800ia access switches, the switches in the stack assign incrementing switch numbers to themselves (automatic stacking capability).
    • If you add Catalyst 6800ia access switches to a configured IA client, the additional switches assign incrementing switch numbers to themselves.
    • The IA client configuration does not persist if the access switch number changes.

    Maximum number of VLANs per IA client stack

    You can set upto 1,000 VLANs, we recommend to set not more than 20 VLANs per FEX.

    Maximum Number of Port Channels

    512

  • IA client ports do not support these features:

blank.gif Configuring EtherChannels with a combination of FEX Ports using different FEX-IDs or a combination of FEX host port and an IA parent linecard port is not supported. However, FEX host port channel from the same FEX is supported.

blank.gif FEX host port EtherChannel load balancing is not supported.

blank.gif Port debounce timer

blank.gif UDLR tunnel ARP and IGMP proxy

blank.gif Uni-Directional Link Routing (UDLR)

blank.gif IEEE 802.1Q tunneling

blank.gif VLAN Mapping

blank.gif VLAN Translation

blank.gif IEEE 802.1Q custom ethertypes

blank.gif L2PT - Layer 2 protocol tunneling

blank.gif L2PT - Layer 2 protocol tunneling on trunk ports

blank.gif 802.1ad tunneling

blank.gif Port security on 802.1Q tunnel ports

blank.gif Private VLANs (PVLAN)

blank.gif VACL capture

blank.gif Per-VLAN load balancing for Advanced QinQ service mapping

blank.gif Cisco TrustSec NDAC (Network Device Admission Control)

blank.gif Cisco TrustSec confidentiality and integrity with MACsec (IEEE 802.1AE)

blank.gif Cisco TrustSec identity port mapping

blank.gif Network edge authentication topology (NEAT)

blank.gif AutoQoS

blank.gif MQC queuing policy support

blank.gif QoS aggregated DSCP values for WRED

blank.gif QoS aggregated precedence values for WRED

blank.gif Class based weighted fair queuing (CBWFQ)

blank.gif Class-based shaping

blank.gif DiffServ-compliant dWRED

blank.gif Diffserv-compliant WRED

blank.gif Selective packet discard (SPD)

blank.gif Weighted fair queueing (WFQ)

blank.gif Weighted RED (WRED)

blank.gif QoS policer rate increase to 256G

blank.gif Ethernet over MPLS (EoMPLS) - IEEE 802.1q Tag Stacking

blank.gif H-VPLS N-PE redundancy for QinQ access

blank.gif Connectivity fault management (CFM)

blank.gif Ethernet connectivity fault management (E-CFM)

blank.gif Ethernet local management interface (LMI) at provider edge (PE)

blank.gif Ethernet operations, administration, and Maintenance (OAM)

blank.gif Ethernet-OAM 3.0: CFM over BD, Untagged

blank.gif IEEE 802.1ag - D8.1 standard Compliant CFM, Y.1731 multicast LBM / AIS / RDI / LCK, IP SLA for Ethernet

blank.gif IEEE 802.1ag Compliant CFM (D8.1)

  • To use an IA client port as a SPAN destination, add the IA client port VLAN to the SPAN allowed VLAN list with the switchport trunk allowed vlan command.
  • When FEX IA parent-client link portchannel is configured as SPAN source in Tx direction or both directions, the SPAN destination should not be on the same FEX. This is applicable for both stacked and standalone FEX.
  • When a queuing policy is attached to a FEX interface or removed from a FEX interface, the policy will be propagated to all the interfaces in the same FEX stack. In the case of a module deletion (using module provision command) from a FEX stack the policy will be removed from the remaining modules in the same stack. This is because the module deletion will trigger a removal policy event for the interfaces and any delete policy event will propagate to all the interfaces in the stack. This is expected behavior from the current design point of view.
  • IA client port QoS:

blank.gif Configure ingress QoS on the IA parent port-channel interface.

blank.gif The egress QoS configuration on IA client ports is not configurable.

blank.gif Port architecture (Rx/Tx): 1p3q3t

 

1p3q3t strict-priority egress queue (queue 1)

CoS

Not supported

DSCP

32, 33, 40–47

Tail-drop

100% (nonconfigurable)

WRED-drop

Not supported

1p3q3t standard egress queue 2
(high priority)

Threshold 1

CoS

Not supported

DSCP

16–23, 26–31, 34–39

Tail-drop

Disabled; 100%

WRED-drop

Not supported

Thresholds 2

CoS

Not supported

DSCP

24

Tail-drop

Disabled; 100%

WRED-drop

Not supported

Thresholds 3

CoS

Not supported

DSCP

48-63

Tail-drop

Disabled; 100%

WRED-drop

Not supported

1p3q3t standard egress queue 3
(medium priority)

Threshold 1

CoS

Not supported

DSCP

25

Tail-drop

Disabled; 70%

WRED-drop

Not supported

Threshold 2

CoS

Not supported

DSCP

None.

Tail-drop

Disabled; 100%

WRED-drop

Not supported

Thresholds 3

CoS

Not supported

DSCP

0–7

Tail-drop

Disabled; 100%

WRED-drop

Not supported

1p3q3t standard egress queue 4
(lowest priority)

Threshold 1

CoS

Not supported

DSCP

8, 9, 11, 13, 15

Tail-drop

Disabled; 70%

WRED-drop

Not supported

Threshold 2

CoS

Not supported

DSCP

10, 12, 14

Tail-drop

Disabled; 100%

WRED-drop

Not supported

Threshold 3

CoS

Not supported

DSCP

None.

Tail-drop

Disabled; 100%

WRED-drop

Not supported

  • Maximum dot1x hosts supported with IBNS 1.0 configuration is 1000.

Information About Instant Access

The Instant Access (IA) feature supports multiple Catalyst 6800ia access switches that function as clients of the IA parent switch. The IA parent and client switches form a single extended switch with a single management domain, managed by the IA parent.

The IA parent uses the Satellite Discovery Protocol (SDP) and the Satellite Registration Protocol (SRP) to automatically discover IA clients when they connect and monitor the IA client-parent link. The IA parent upgrades the IA client software image if it is not the same as the parent FEX Image Bundle.

The IA parent features are applied to IA client FEX ports. The IA clients do not perform any local packet forwarding. All traffic originating from IA client ports are sent to the IA parent, which makes all the switching and forwarding decisions.

The IA client switches support the following online diagnostic tests:

Default Settings for Instant Access

None.

How to Configure Instant Access

Configure Instant Access Staggered Initialization Mode

Instant Access staggered initialization mode avoids any excessively high CPU utilization that might occur if multiple IA clients attempt to initialize simultaneously. To configure Instant Access staggered initialization mode, perform this task:

 

Command
Purpose

Router(config)# fex stagger delay_value

Configures Instant Access staggered initialization mode. The delay_value can be 0 through 500.

Note The recommended delay_value is 120.

 

This example shows how to configure Instant Access staggered mode:

Router# configure terminal
Router(config)# fex stagger 120

Enable FEX Auto-Config

FEX Auto-config mode allows increased scalability with reduced configuration. Configuration using Auto-config includes FEX ID selection, Port-channel ID selection, converting RSL port to FEX-fabric mode, and RSL port bundling.

To enable FEX auto-config, perform this task:

 

Command
Purpose

Router(config)# fex auto-config

Enable FEX auto-config support globally.

 

This example shows how to configure FEX auto-config mode:

Router# configure terminal
Router(config)# fex auto-config

 

Enable IA Client Preprovisioning

To allow IA client port configuration before the IA client is connected, perform this task:

 

Command
Purpose

Router# module provision create fex fex_number type { C6800IA-48FPD | C6800IA-48TD | C6800IA-48FPDR | WS-C3560CX-12PD-S | WS-C3560CX-8XPD-S } [ slot switch_number ]

Enables IA client port configuration before the IA client is connected. Enter the slot switch_number keyword and argument to enable configuration of a specific IA client stack member or an additional stack member before it is added to the IA client stack.

WS-C3560CX-8XPD-S and WS-C3560CX-12PD-S will undergo a number of reloads as FEX client before coming online based on the following conditions:

  • Reload1: To convert itself from switch mode to FEX mode on receiving the SDP packet from controller
  • Reload2: If a mismatch of IOS version occurs between FEX controller and FEX client, the FEX client downloads the image from controller and boots up.
  • Reload3: If a mismatch of MTU occurs between FEX controller and FEX client, the FEX client reloads again to change the MTU of FEX host ports.

Configure Instant Access Port-Channel Interfaces

To create a port channel interface to support IA clients, perform this task:

 

Command
Purpose

Step 1

Router(config)# interface port-channel group_number

Creates the port channel interface. The group_number can be 1 through 512, up to a maximum of 512 port-channel interfaces (42 port-channel interfaces can be used to support IA clients).

Note If desired, you can configure the group_number to match the IA client FEX number.

Step 2

Router(config-if)# switchport

Configures the port channel interface for Layer 2 switching.

Step 3

Router(config-if)# switchport mode fex-fabric

Configures the port channel interface to support IA clients.

Step 4

Router(config-if)# fex associate fex_number

Configures the IA client FEX number.

  • The valid value range is 101–199.
  • Maximum of 42 IA client FEX numbers.

This example shows how to create port channel interface 1 and configure it to support IA FEX number 118:

Router# configure terminal
Router(config)# interface port-channel 118
Router(config-if)# switchport
Router(config-if)# switchport mode fex-fabric
Router(config-if)# fex associate 118

Configure Instant Access Channel Groups

To configure channel groups to support IA clients, perform this task for the 10 Gigabit Ethernet LAN ports that connect to IA clients:

 

Command
Purpose

Step 1

Router(config)# interface range first_10ge_port, last_10ge_port

Selects the ports to configure.

Step 2

Router(config-if)# switchport

Configures the port channel interface for Layer 2 switching.

Step 3

Router(config-if)# switchport mode fex-fabric

Configures the port channel interface to support IA clients.

Step 4

Router(config-if)# channel-group group_number mode on

Configures the LAN port in an IA Client port channel and configures the mode as on.

note.gif

Noteblank.gif More links can be added to the channel group at any time.


This example shows how to configure 10 Gigabit Ethernet ports 1/2/5 and 2/2/5 into port channel 118 with mode on :

Router# configure terminal
Router(config)# interface range tengigabitethernet 1/2/5, 2/2/5

Router(config-if)# switchport

Router(config-if)# switchport mode fex-fabric

Router(config-if)# channel-group 118 mode on
Router(config-if)# end
 

This example shows how to verify the IA configuration when the IA client is connected:

Router# show fex 118 detail
FEX: 118 Description: FEX0118 state: online
FEX version: version_string
Extender Model: C6800IA-48TD, Extender Serial: serial_number
FCP ready: yes
Image Version Check: enforced
Fabric Portchannel Ports: 2
Fabric port for control traffic: Te1/2/5
Fabric interface state:
Po20 - Interface Up.
Te1/2/5 - Interface Up. state: bound
Te2/2/5 - Interface Up. state: bound

Identify Connected IA Client Stack Modules

Identify IA Client Stack Modules by Serial Number

This example shows how to identify IA client stack modules by serial number:

Router# show mod fex 101
Switch Number: 101 Role: FEX
 
Mod Ports Card Type Model Serial No.
 
--- ----- -------------------------------------- ------------------ -----------
 
1 48 C6800IA 48GE C6800IA-48TD FOC1737W0PF
 
2 48 C6800IA 48GE POE C6800IA-48FPD FOC1736Z036
 
3 48 C6800IA 48GE C6800IA-48TD FOC1737W0NP
 
4 48 C6800IA 48GE POE C6800IA-48FPD FOC1741S58N
 
5 48 C6800IA 48GE POE C6800IA-48FPD FOC1736Z03L
 

Identify IA Client Modules by Beacon LED

Router(config)# hw-module fex <> slot <> led beacon

This example shows how to activate the beacon LED on IA client 118, slot 1:

Router(config)# hw-module fex 118 slot 1 led beacon
 

This example shows how to verify the beacon LED on IA client 118, slot 1:

Router(config)# show hw-module fex led beacon
C6K FEX BLUE BEACON CONFIG
----------------------------------
hw-module fex 118 slot 1 led beacon
 

Easy FEX

Easy FEX allows interface naming of FEX host port interfaces. To create interface naming, perform this task:

 

Command
Purpose

Router(config-if)# alias string

Configures alias under native FEX interface sub-mode.

Router(config-fex)# alias string

 

Configures a common alias name for all the FEX interfaces under a particular FEX-id.

Router(config)# interface alias string

 

Configures interface with the help of alias set.

This example shows all aliases using ‘all’ keyword:

fex-vss# show interfaces alias all
Interface Name Alias
---------------------------------------- --------------------
TenGigabitEthernet1/4/5 test
GigabitEthernet101/1/0/1 my_fex_loc_A/1/0/1
GigabitEthernet101/1/0/2 my_fex_loc_A/1/0/2
GigabitEthernet101/1/0/3 my_fex_loc_A/1/0/3
GigabitEthernet101/1/0/4 my_fex_loc_A/1/0/4
GigabitEthernet101/1/0/5 my_fex_loc_A/1/0/5

 

Renumbering FEX Switch-ID

The renumbering of IA clients can be managed using switch-id allocation from controller, after stack boot up. Also, a priority can be assigned to the FEX members to take over as the master switch.

The following conditions must exist for successful execution of FEX switch-id allocation:

blank.gif For renumbering, the source slot should be online and the target slot should be offline.

blank.gif If the source slot FEX type is different than target slot FEX type, the interface configurations will be lost if you proceed with renumbering.

blank.gif Same target slot cannot be used for renumbering multiple source slots.

blank.gif Same source slot cannot be renumbered to multiple target slot.

blank.gif You can enter multiple renumbering entries along with different swapping scenarios.

blank.gif When priority is modified for a member IA, the whole stack will reload.

blank.gif During In Service Software Upgrade (ISSU) process, switch-id renumbering or priority changes are not allowed.

To renumber FEX switch-id and assign priority, perform this task:

 

Command
Purpose

Step 1

Switch# module provision update fex fex_id

Enters into switch renumber sub-mode.

Step 2

Switch(exec-fex-update)# renumber source_slot to target_slot

Renumbers source_slot to target_slot

Step 3

Switch(exec-fex-update)# priority source_slot value number

 

Assigns the mentioned priority number to the source_slot.

Step 4

Switch(exec-fex-update)# commit

Commits all entries entered under exec-fex-update sub-mode.

note.gif

Noteblank.gif After the commit operation, you will be prompted whether you want to release the old source-vslot or not. This confirmation will not be asked only in a switch-id swap scenario (for example, renumber 1 to 2 and renumber 2 to 1) because both renumbering are done in a single commit operation.


To renumber FEX switch-id when scale is set to maximum FEX slots, perform this task:

 

Command
Purpose

Step 1

Switch# module provision update fex fex_id temp-vslot-allow enable

When maximum vslots are already allocated, temp-vslot-allow will enable the temporary vslot module to come online.

Step 2

Switch# module provision update fex fex_id

Enters into switch renumber sub-mode.

Step 3

Switch(exec-fex-update)# renumber source_slot to target_slot

Renumbers source_slot to target_slot

Step 4

Switch(exec-fex-update)# priority source_slot value number

 

Assigns the mentioned priority number to the source_slot.

Step 5

Switch(exec-fex-update)# commit

Commits all entries entered under exec-fex-update sub-mode.

Step 6

Switch# module provision update fex fex_id temp-vslot-allow disable

Disables the temporary vslot module to go offline.

note.gif

Noteblank.gif After the commit operation, you will be prompted whether you want to release the old source-vslot or not. This confirmation will not be asked only in a switch-id swap scenario (for example, renumber 1 to 2 and renumber 2 to 1) because both renumbering are done in a single commit operation.


Example: Renumbering FEX switch-id and setting priority

Switch# module provision update fex 101

Switch(exec-fex-update) renumber 3 to 4

Switch(exec-fex-update) priority 2 value 1

%FEX 101 will reload upon commit.

Are you sure you want to proceed? [no]: yes

Switch(exec-fex-update)#commit

%Do you want to release FEX 101 module 3 source interface configs(vslot) after module offline? [no]: yes

%FEX 101 All modules will reload.

Are you sure you want to proceed? [no]: yes

Example: Identifying if temporary vslot is online

This example shows how to identify when a particular temporary FEX vslot is online:

Switch# show fex system platform usage
FEX id usage details
Fex-ids inuse: 150
Fex-ids online: 150
Total Used Free
----- ---- ----
42 1 41
FEX slot usage details
FEX-id Switch-id Vslot Pslot Status
------ --------- ----- ----- ------
150 3 51 2 In-use
150 3 52 3 In-use
150 3 53 5 Reserved
150 3 55 4 In-use
150 3 92 1 Temp-In-use
Total Used Reserved Temp-Use/Free Free
----- ---- -------- ------------- ----
47 3 1 1/4 42
Current Temp vslot allowed FEXs: 150
Current Temp VSLOT usage:
------------------------
FEX 150 module 1
FEX ports usage details
FEX-id Switch-id Ports
------ --------- -----
150 3 192
Total Used Free
----- ---- ----
2016 192 1824
Stack members usage details
FEX-id Switch-id Used Free

 

Example: Identifying FEX IDs where temp-vslot-allow command is enabled

This example verifies the active entries under sub-mode and also the FEX IDs on which "temp-vslot-allow" is enabled.

Switch(exec-fex-update)#show
Current module renumber mappings for FEX 101
--------------------------------------------
renumber 1 to 2
Current module Priority mappings for FEX 101
--------------------------------------------
priority 1 value 15
Temp vslots allowed:YES
Current Temp vslot allowed FEXs:101
Switch(exec-fex-update)#

 

Configure IA Clients

The configuration for IA clients can be entered on the IA parent before or after the IA clients are connected. IA client 10-Gigabit Ethernet ports require no configuration. IA client Gigabit Ethernet ports use this format:

gigabitethernet / fex_number / access_switch_number /0/ port_number

blank.gif fex_number —The IA client FEX number:

—Maximum of 42 IA FEX number s.

—The valid value range is 101–199.

blank.gif access_switch_number —The access switch number:

—The valid value range is 1-5.

—Multiple-switch stacks assign incrementing switch numbers to themselves.

—See the “Identify Connected IA Client Stack Modules” section.

blank.gif The third interface parameter is always zero.

blank.gif The port_number valid value range is 1–48.

note.gif

Noteblank.gif IA client configuration does not persist if the access switch number changes.


 

Display or Clear SDP and SRP Traffic

To display the counters that record the SDP packet traffic on IA client 118, enter the following command:

Router# show fex 118 protocol | incl SDP
130 SDP pkts sent
129 SDP pkts received
130 SDP pkts sent
129 SDP pkts received
 
note.gif

Noteblank.gif The command displays a sent and received value for each link in the IA channel group.


To clear the protocol counters, enter the clear fex fex_number { sdp | srp } command.

Upgrade FEX using In-Service Software Upgrade (ISSU) Process

To upgrade the software image of the FEX hosts using ISSU process, perform the following steps:

 

Command
Purpose

Step 1

Router# issu loadversion device:filename

Initiates the ISSU process.

Step 2

Router# issu runversion

Forces a switchover.

Step 3

Router# issu acceptversion

Stops the rollback timer and ensures that the software upgrade is not automatically aborted during the ISSU process.

Step 4

Router# issu runversion fex < fex-id | all >

Forces a switchover of the active to the standby processor and starts the image download and upgrade procedure on the FEX (6800IA). The FEX initiates the image download from the new software bundle of the Sup2T. If you are using FEX stacks, the stack master initiates the image download for its members.

Step 5

Router# issu commitversion

Upgrades the VSS standby chassis and completes the ISSU process.

Step 6

Router# show issu state detail

Displays the state and the current version of the RPs after the ISSU process.

Configure Optional Parameters for an IA Client

Enter the IA Client Configuration Mode

To enter the IA client configuration mode, perform this task:

 

Command
Purpose

Router(config)# fex fex_number

 

Enters IA client configuration mode.

Note Sets the IA client description to FEX fex_number.

Configure a Description

To configure a description for the IA client or for each module in the IA client stack, perform this task:

 

Command
Purpose

Router(config-fex)# [ module module_number ] description description_string

Configures a description for the IA FEX number or for a module in the IA client stack.

Configure the Custom Location Type Feature

You can configure the custom location type feature for the IA client in IA client configuration mode. See these publications for information about the location command:

http://www.cisco.com/en/US/docs/ios-xml/ios/cether/command/ce-cr-book.html

http://www.cisco.com/en/US/docs/ios-xml/ios/cether/command/ce-e1.html

note.gif

Noteblank.gif The location commands support the optional fex-location keyword for IA clients.


Configure MTU

You can configure MTU on the IA FEX using the mtu command in fex config mode. In an IA client stack, the configured MTU value is applied to all the host members in the stack.

To configure MTU for an IA client, perform this task:

 

Command
Purpose

Router# configure terminal

Enters the global configuration mode.

Router(config)# fex 110

Enters IA client configuration mode.

Router(config-fex)# mtu 2000

Resets the MTU value for the FEX system. All the FEX ports will be set to use the new MTU value.

The default MTU value for a FEX host port is 9216.

Note For Cisco Catalyst C6840 series switch, the maximum supported MTU for native interface is 9154.The default MTU value is 1500. If the MTU of peer (Catalyst 6880 or Sup2T) is configured higher than 9154, the packet will not be processed. When using existing configuration from a Catalyst 6880 or Sup2T, ensure that the MTU is reset or removed.

Router# end

Exits the global configuration mode.

Note Reload the FEX for the MTU change to take effect.

If you want to avoid reloading the FEX, you can configure an explicit connectionless network service (CLNS) MTU size on the IA client and peer ports as shown in the following example:

Router# configure terminal
Router(config)# interface interface Gig118/1/0/1
Router(config-if)# ip router isis
Router(config-if)# clns mtu 1497