[j-nsp] J4300 MTU question

[Ben Dale]

Herman,

You are seeing this error because you are changing the MTU under [edit 
interfaces e1-1/0/0 unit 0 family] to be larger than the MTU of the 
interface itself (the "device" MTU).  On an E1, you need to have a 
device MTU at least 4 bytes larger (presumably to allow for 
encapsulation/headers).  To get the result I think you are trying to 
achieve try:

[edit interfaces e1-0/0/2]
btox at merlin# show 
description "I wish i was gig";
mtu 2004;
clocking internal;
unit 0 {
    family inet {
        mtu 2000;
    }
}

Cheers,

Ben

Herman Ng wrote:
> Hi,
> Another question on changing J4300 MTU size:
>
> As show below, on the e1 interface, the Media MTU is 1504 and the Protocol
> MTU is 1500.
> But when try to change the Media MTU to 2000: *set interfaces e1-1/0/0 mtu
> 2000, and commit.*
> It give *Family MTU is too large relative to device MTU*
>
> What is this error mean, and how to fix it?
>
> Any help would be appreciated.
> Thanks
> Herman
>
> root at GPA-BG-JR1> show interfaces e1-1/0/0
>   Interface index: 139, SNMP ifIndex: 60
>   Link-level type: PPP, *MTU: 1504*, Clocking: Internal, Speed: 128kbps,
>   Loopback: None, FCS: 16, Framing: G704
>   Device flags   : Present Running
>   Interface flags: Point-To-Point SNMP-Traps 16384
>   Link flags     : Keepalives
>   Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3
>   Keepalive: Input: 111526 (00:00:08 ago), Output: 249826 (00:00:05 ago)
>   LCP state: Opened
>   NCP state: inet: Opened, inet6: Not-configured, iso: Not-configured, mpls:
>   Not-configured
>   CHAP state: Not-configured
>   CoS queues     : 8 supported
>   Last flapped   : 2006-05-10 15:53:18 GST (9w2d 22:00 ago)
>   Input rate     : 232 bps (0 pps)
>   Output rate    : 176 bps (0 pps)
>   DS1   alarms   : None
>   DS1   defects  : None
>
>   Logical interface e1-1/0/0.0 (Index 69) (SNMP ifIndex 62)
>     Flags: Point-To-Point SNMP-Traps Encapsulation: PPP
>     Protocol inet, *MTU: 1500*
>       Flags: None
>       Addresses, Flags: Is-Preferred Is-Primary
>         Destination: 194.170.102.0/30, Local: 194.170.102.2,
>         Broadcast: 194.170.102.3
>
> root at GPA-BG-JR1>
>
> root at GPA-BG-JR1# *set interfaces e1-1/0/0 mtu 2000*
> Jul 15 13:51:14  GPA-BG-JR1 mgd[10045]: UI_CFG_AUDIT_SET: User 'root' set:
> [interfaces e1-1/0/0 mtu] <unconfigured> -> "2000"
> Jul 15 13:51:14  GPA-BG-JR1 mgd[10045]: UI_CMDLINE_READ_LINE: User 'root',
> command 'set interfaces e1-1/0/0 mtu 2000 ' [edit]
> root at GPA-BG-JR1# commit
> Jul 15 13:52:03  GPA-BG-JR1 mgd[10045]: UI_CMDLINE_READ_LINE: User 'root',
> command 'commit '
> Jul 15 13:52:03  GPA-BG-JR1 mgd[10045]: UI_COMMIT: User 'root' performed
> commit: no comment
> Jul 15 13:52:03  GPA-BG-JR1 mgd[10045]: UI_COMMIT_PROGRESS: commit:
> exporting juniper.conf
> Jul 15 13:52:03  GPA-BG-JR1 mgd[10045]: UI_COMMIT_PROGRESS: commit:
> expanding groups
> Jul 15 13:52:03  GPA-BG-JR1 mgd[10045]: UI_COMMIT_PROGRESS: commit: finished
> expanding groups [edit interfaces e1-1/0/0 unit 0 family]
> *  'inet'
>      Family MTU is too large relative to device MTU
> *
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