[j-nsp] J6350 Jumbo frame MTU and OSPF setting

[Harris Hui]

Dear all,

We had subscribed a private line circuit between 2 different data center
for Data Backup and replication. The bandwidth of the private line is
100Mbps.

According to the provider, The Circuit is Built across their
 Network as 2 STS1's or High Speed DS3's which equals 100meg.

Their GE port setting as follows.

MTU Size - 9600
Auto Negotiation - OFF
Remote Client Fail - Disabled.

The private circuit is connected directly to the fiber module of our J6350
Services router at each Data Center. The Circuit is up and running but when
we perform some TCP throughput test, we only get ~3Mbps for a Single TCP
session with iPerf and the latency between two data center across the
private circuit is ~80ms.

I am trying to configure our J6350 fiber interface to MTU 9192 to get a
better TCP throughput. However, I can only able to configure the MTU size
below 1500, when I configure the MTU to 9192 and commit the changes, it
still shows MTU 1500 on the physical interface.

Do you have any experience on using Jumbo frame MTU size on the J6350? We
are also running OSPF across the private circuit, is JUNOS support "OSPF
ignore-mtu" like cisco?

Please advise.

Fiber module
================================================
FPC 3            REV 18   750-013599   AAAH7361          FPC
  PIC 0                                                  1x GE SFP
    Xcvr 0       REV 02   740-011614   PG336CS           SFP-LX10

show interfaces ge-3/0/0
speed 1g;
mtu 1400;
link-mode full-duplex;
gigether-options {
    no-auto-negotiation;
}
unit 0 {
    family inet {
        address xxx.xxx.xxx.253/30;
    }
}

harris at J6350# run show interfaces ge-3/0/0
Physical interface: ge-3/0/0, Enabled, Physical link is Up
  Interface index: 152, SNMP ifIndex: 184
  Link-level type: Ethernet, MTU: 1400, Speed: 1000mbps, BPDU Error: None,
MAC-REWRITE Error: None, Loopback: Disabled,
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation:
Disabled, Remote fault: Online
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x4000
  Link flags     : None
  CoS queues     : 8 supported, 8 maximum usable queues
  Current address: b0:c6:9a:87:35:36, Hardware address: b0:c6:9a:87:35:36
  Last flapped   : 2010-09-27 02:32:24 UTC (4d 02:29 ago)
  Input rate     : 0 bps (0 pps)
  Output rate    : 0 bps (0 pps)
  Active alarms  : None
  Active defects : None

show interfaces ge-3/0/0
speed 1g;
mtu 9192;
link-mode full-duplex;
gigether-options {
    no-auto-negotiation;
}
unit 0 {
    family inet {
        address xxx.xxx.xxx.253/30;
    }
}

run show interfaces ge-3/0/0
Physical interface: ge-3/0/0, Enabled, Physical link is Up
  Interface index: 152, SNMP ifIndex: 184
  Link-level type: Ethernet, MTU: 1514, Speed: 1000mbps, BPDU Error: None,
MAC-REWRITE Error: None, Loopback: Disabled,
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation:
Disabled, Remote fault: Online
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x4000
  Link flags     : None
  CoS queues     : 8 supported, 8 maximum usable queues
  Current address: b0:c6:9a:87:35:36, Hardware address: b0:c6:9a:87:35:36
  Last flapped   : 2010-09-27 02:32:24 UTC (4d 02:35 ago)
  Input rate     : 0 bps (0 pps)
  Output rate    : 1192 bps (2 pps)
  Active alarms  : None
  Active defects : None


Thanks
Harris