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Dell Force10 S55T FTOS Command Line Reference Guide for the S55 System FTOS 8. - Page 527

ip mtu

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ip mtu e Set the IP MTU (frame size) of the packet transmitted by the RPM for the line card interface. If the packet must be fragmented, FTOS sets the size of the fragmented packets to the size specified in this command. Syntax ip mtu value To return to the default IP MTU value, enter no ip mtu. Parameters value Enter the maximum MTU size if the IP packet is fragmented. Default: 1500 bytes Range: 576 to 9234 Defaults 1500 bytes Command Modes INTERFACE (Gigabit Ethernet and 10 Gigabit Ethernet interfaces) Command History Version 8.1.1.0 pre-Version 6.1.1.0 Introduced on E-Series ExaScale Introduced for E-Series Usage When you enter no mtu command, FTOS reduces the ip mtu value to 1536 bytes. To return the IP Information MTU value to the default, enter no ip mtu. You must compensate for Layer 2 header when configuring link MTU on an Ethernet interface or FTOS may not fragment packets. If the packet includes a Layer 2 header, the difference between the link MTU and IP MTU (ip mtu command) must be enough bytes to include for the Layer 2 header. Link MTU and IP MTU considerations for Port Channels and VLANs are as follows. Port Channels: All members must have the same link MTU value and the same IP MTU value. • The Port Channel link MTU and IP MTU must be less than or equal to the link MTU and IP MTU values configured on the channel members. Example: if the members have a link MTU of 2100 and an IP MTU 2000, the Port Channel's MTU values cannot be higher than 2100 for link MTU or 2000 bytes for IP MTU. VLANs: • All members of a VLAN must have same IP MTU value. • Members can have different Link MTU values. Tagged members must have a link MTU 4 bytes higher than untagged members to account for the packet tag. • The VLAN link MTU and IP MTU must be less than or equal to the link MTU and IP MTU values configured on the VLAN members. Example: The VLAN contains tagged members with Link MTU of 1522 and IP MTU of 1500 and untagged members with Link MTU of 1518 and IP MTU of 1500. The VLAN's Link MTU cannot be higher than 1518 bytes and its IP MTU cannot be higher than 1500 bytes. IPv4 Routing | 527

Section	Page
About this Guide	11
Objectives	11
Audience	11
Conventions	11
Information Symbols	12
Related Documents	12
CLI Basics	13
Accessing the Command Line	13
Multiple Configuration Users	14
Navigating the Command Line Interface	14
Obtaining Help	15
Using the Keyword No	17
Filtering show Commands	17
Displaying All Output	18
Filtering Command Output Multiple Times	18
Command Modes	18
EXEC Mode	19
EXEC Privilege Mode	19
CONFIGURATION Mode	19
INTERFACE Mode	19
LINE Mode	20
TRACE-LIST Mode	20
MAC ACCESS LIST Mode	20
IP ACCESS LIST Mode	21
ROUTE-MAP Mode	21
PREFIX-LIST Mode	21
AS-PATH ACL Mode	21
IP COMMUNITY LIST Mode	22
REDIRECT-LIST Mode	22
SPANNING TREE Mode	22
Per-VLAN SPANNING TREE Plus Mode	22
RAPID SPANNING TREE Mode	23
MULTIPLE SPANNING TREE Mode	23
PROTOCOL GVRP Mode	23
ROUTER OSPF Mode	23
ROUTER RIP Mode	24
ROUTER BGP Mode	24
Determining the Chassis Mode	24
File Management	25
Overview	25
Basic File Management Commands	25
Control and Monitoring	63
Overview	63
Commands	63
802.1ag	157
Overview	157
Commands	157
S55 u-Boot	169
Overview	169
Commands	169
Access Control Lists (ACL)	175
Overview	175
Commands Common to all ACL Types	175
Common IP ACL Commands	177
Standard IP ACL Commands	181
Extended IP ACL Commands	188
Common MAC Access List Commands	219
Standard MAC ACL Commands	222
Extended MAC ACL Commands	226
IP Prefix List Commands	232
Route Map Commands	238
AS-Path Commands	256
IP Community List Commands	260
Border Gateway Protocol IPv4(BGPv4)	265
Overview	265
BGPv4 Commands	266
MBGP Commands	342
BGP Extended Communities (RFC 4360)	367
Bare Metal Provisioning	377
Overview	377
Commands	377
Content Addressable Memory (CAM)	381
Overview	381
CAM Profile Commands	381
Important Points to Remember	381
Dynamic Host Configuration Protocol (DHCP)	395
Overview	395
Commands to Configure the System to be a DHCP Server	395
Commands to Configure Secure DHCP	403
Dell Force10 Resilient Ring Protocol (FRRP)	409
Overview	409
Commands	409
Important Points to Remember	409
GARP VLAN Registration (GVRP)	417
Overview	417
Commands	417
Important Points to Remember	418
Internet Group Management Protocol (IGMP)	427
Overview	427
IGMP Commands	427
Important Points to Remember	427
IGMP Snooping Commands	438
Important Points to Remember for IGMP Snooping	438
Important Points to Remember for IGMP Querier	438
Interfaces	443
Overview	443
Basic Interface Commands	443
Port Channel Commands	499
IPv4 Routing	509
Overview	509
Commands	509
IPv6 Access Control Lists (IPv6 ACLs)	561
Overview	561
Important Points to Remember	561
IPv6 ACL Commands	561
IPv6 Route Map Commands	586
IPv6 Basics	591
Overview	591
Commands	591
iSCSI Optimization	603
Overview	603
Link Aggregation Control Protocol (LACP)	611
Overview	611
Commands	611
Layer 2	619
Overview	619
MAC Addressing Commands	619
Virtual LAN (VLAN) Commands	637
Link Layer Detection Protocol (LLDP)	647
Overview	647
Commands	647
LLDP-MED Commands	656
Multiple Spanning Tree Protocol (MSTP)	665
Overview	665
Commands	665
Multicast	679
Overview	679
IPv4 Multicast Commands	679
IPv6 Multicast Commands	687
Neighbor Discovery Protocol (NDP)	693
Overview	693
Commands	693
Open Shortest Path First (OSPFv2 and OSPFv3)	701
Overview	701
OSPFv2 Commands	701
PIM-Sparse Mode (PIM-SM)	759
Overview	759
IPv4 PIM-Sparse Mode Commands	759
PIM-Source Specific Mode (PIM-SSM)	775
Overview	775
IPv4 PIM Commands	775
IPv4 PIM-Source Specific Mode COmmands	775
Port Monitoring	779
Overview	779
Commands	779
Important Points to Remember	779
Private VLAN (PVLAN)	785
Overview	785
Commands	785
Private VLAN Concepts	785
Per-VLAN Spanning Tree plus (PVST+)	795
Overview	795
Commands	795
Quality of Service (QoS)	807
Overview	807
Global Configuration Commands	807
Per-Port QoS Commands	808
Policy-Based QoS Commands	816
Important Points to Remember—multicast-bandwidth option	830
Queue-Level Debugging	852
Router Information Protocol (RIP)	865
Overview	865
Commands	865
Remote Monitoring (RMON)	885
Overview	885
Commands	885
Rapid Spanning Tree Protocol (RSTP)	897
Overview	897
Commands	897
Security	907
Overview	907
Commands	907
AAA Accounting Commands	907
Authorization and Privilege Commands	910
Authentication and Password Commands	914
RADIUS Commands	926
TACACS+ Commands	931
Port Authentication (802.1X) Commands	934
Important Points to Remember	934
SSH Server and SCP Commands	942
Secure DHCP Commands	954
Service Provider Bridging	959
Overview	959
Commands	959
Important Points to Remember	959
sFlow	965
Overview	965
Important Points to Remember	965
Commands	966
SNMP and Syslog	975
Overview	975
SNMP Commands	975
Important Points to Remember	976
Syslog Commands	991
Storm Control	1005
Overview	1005
Commands	1005
Important Points to Remember	1005
S-Series Stacking Commands	1015
Overview	1015
Commands	1015
Spanning Tree Protocol (STP)	1029
Overview	1029
Commands	1029
Time and Network Time Protocol (NTP)	1039
Overview	1039
Commands	1039
VLAN Stacking	1055
Overview	1055
Commands	1055
Important Points to Remember	1055
Virtual Router Redundancy Protocol (VRRP)	1065
Overview	1065
Commands	1065
S-Series Debugging and Diagnostics	1077
Diagnostics and Monitoring Commands	1077
Offline Diagnostic Commands	1078
Important Points to Remember	1078
Buffer Tuning Commands	1080
Hardware Commands	1085
ICMP Message Types	1095
SNMP Traps	1097
Index	1101

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IPv4 Routing

527

ip mtu

Set the IP MTU (frame size) of the packet transmitted by the RPM for the line card interface. If the

packet must be fragmented, FTOS sets the size of the fragmented packets to the size specified in this

command.

Syntax

ip mtu

value

To return to the default IP MTU value, enter

no ip mtu

Parameters

Defaults

1500 bytes

Command Modes

INTERFACE (Gigabit Ethernet and 10 Gigabit Ethernet interfaces)

Command

History

Usage

Information

When you enter

no mtu

command, FTOS reduces the

ip mtu

value to 1536 bytes. To return the IP

MTU value to the default, enter

no ip mtu

You must compensate for Layer 2 header when configuring link MTU on an Ethernet interface or

FTOS may not fragment packets. If the packet includes a Layer 2 header, the difference between the

link MTU and IP MTU (

ip mtu

command) must be enough bytes to include for the Layer 2 header.

Link MTU and IP MTU considerations for Port Channels and VLANs are as follows.

Port Channels:

All members must have the same link MTU value and the same IP MTU value.

•

The Port Channel link MTU and IP MTU must be less than or equal to the link MTU and IP MTU

values configured on the channel members.

Example: if the members have a link MTU of 2100 and an IP MTU 2000, the Port Channel’s MTU

values cannot be higher than 2100 for link MTU or 2000 bytes for IP MTU.

VLANs:

•

All members of a VLAN must have same IP MTU value.

•

Members can have different Link MTU values. Tagged members must have a link MTU 4 bytes

higher than untagged members to account for the packet tag.

•

The VLAN link MTU and IP MTU must be less than or equal to the link MTU and IP MTU values

configured on the VLAN members.

Example: The VLAN contains tagged members with Link MTU of 1522 and IP MTU of 1500 and

untagged members with Link MTU of 1518 and IP MTU of 1500. The VLAN’s Link MTU cannot be

higher than 1518 bytes and its IP MTU cannot be higher than 1500 bytes.

value

Enter the maximum MTU size if the IP packet is fragmented.

Default: 1500 bytes

Range: 576 to 9234

Version 8.1.1.0

Introduced on E-Series ExaScale

pre-Version 6.1.1.0

Introduced for E-Series