Description

This article provides information about the Maximum supported values for the 1x GE SFP mPIM (old) and 1x GE High-Perf SFP (new sfp mpim) modules and  how to recognize them.

Symptoms

  • Old SFP MPIM, that is 1x GE SFP mPIM, uses a default MTU value of 1514 . It can be increased upto 1628 on 10.3R1,10.1R2,9.6R4,10.2R1, and 10.0R3 releases.
  • New SFP MPIM, that is 1x GE High-Perf SFP, was introduced only in 10.4 or later releases and supports jumbo frames (9010 bytes) . This means that it can use any MTU value upto 9010.

Solution

 

On 1x GE SFP mPIMs, the maximum supported MTU value supported  is 1514 bytes. It will always default to 1514 bytes; no matter what MTU value is manually specified.

Consider the following Example:

Here MTU is manually set to 4000, but it defaults to 1514. 

root@srx# show interfaces ge-1/0/0 
description "Juniper SRX example" ;
enable;
mtu 4000; <<<<<< Specified MTU value                              
unit 0 {
    family inet {
        address 10.0.3.6/30;
    }
    family mpls;
}

  root@srx#run show interfaces ge-1/0/0
  Physical interface: ge-1/0/0, Enabled, Physical link is Up
  Interface index: 154, SNMP ifIndex: 133
  Description: To MCC MX480 #2 (RMCC000185-3) port ge-4/0/1 strands 13 and 14
  Link-level type: Ethernet, MTU: 1514, Speed: 1000mbps, BPDU Error: None, <<<<< Set MTU value of 4000 is ignored and the default value is still in effect
  MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled,
However, MTU values can be increased upto 1628 by using 10.3R1,10.1R2,9.6R4,10.2R1 and 10.0R3 releases.

1x GE High-Perf SFP was introduced only in 10.4 or later and it supports jumbo frames, that is 9010 bytes. This means that any MTU value upto 9010 bytes is supported and can be configured.


How to identify New and Old Mpims :

New and Old SFP MPims can be identified as:

  • 1x GE SFP mPIM : old sfp mpim
  • 1x GE High-Perf SFP: new sfp mpim 


root@vidar-9> show chassis hardware detail
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                AG1111AA7925      SRX240h
Routing Engine   REV 01   750-021793   PW7925            RE-SRX240H
  da0     999 MB  ST72682                                Nand Flash
  usb0 (addr 1)  DWC OTG root hub 0    vendor 0x0000     uhub0
  usb0 (addr 2)  product 0x6254 25172  vendor 0x058f     uhub1
  usb0 (addr 3)  ST72682  High Speed Mode 64218 STMicroelectronics umass0
FPC 0                                                    FPC
  PIC 0                                                  16x GE Base PIC
FPC 1                     750-029145   112009000278      FPC
  PIC 0                                                  1x GE SFP mPIM  <<<<<<< Old mpim
    Xcvr 0       REV 01   740-011620   5200317           SFP-FX
FPC 4                     750-029145   122009000061      FPC
  PIC 0                                                  1x GE SFP mPIM
    Xcvr 0       REV 01   740-011782   P8C0LUJ           SFP-SX
Power Supply 0


root@srx210r08> show chassis hardware detail
node0:
--------------------------------------------------------------------------
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                AE2509AA0074      SRX210h-poe
Routing Engine   REV 43   750-021780   AAAF7163          RE-SRX210H-POE
  da0     999 MB  ST72682                                Nand Flash
  usb0 (addr 1)  DWC OTG root hub 0    vendor 0x0000     uhub0
  usb0 (addr 2)  product 0x005a 90     vendor 0x0409     uhub1
  usb0 (addr 3)  ST72682  High Speed Mode 64218 STMicroelectronics umass0
FPC 0                                                    FPC
  PIC 0                                                  2x GE, 6x FE, 1x 3G
FPC 1            REV 00   750-032730   AABA4322          FPC
  PIC 0                                                  1x GE High-Perf SFP mPIM <<<<<<< New mpim 
    Xcvr 0       REV 01   740-011613   E08F01768         SFP-SX
Power Supply 0