[c-nsp] NPE-G1 support for jumbo frames

[Oliver Boehmer (oboehmer)]

>>> One other "oh surprise!!!" is the fact that the NPE-Gx built-in
ports
>>> won't do over MTU of 1500 when their speed is set to anything other
than
>>> 1000.

>>> Yep.. that's right... set the speed to 100, and the max MTU is 1500.
Set
>>> the speed to 1000, and the max MTU is now 9216. Same port, same
>>> GBIC/copper, same code.

>> Donn, what version of code were you using? This is pretty scary
>> considering that one of the factors of going to NPE-G1 is hoping to
>> take advantage of jumbo frame or at least 1530 on the three ports.
> 
> This behavior occurred under every code revision we tested on the
> NPE-G2's, which was, 12.4.11T, and 12.2.3x-SB trains. It worked fine
> on the PA-FE-TX cards under the same train, just not on the onboard
> ports. 
> 
> Again, once the port is forced to 1000, either fiber or copper, any
> MTU up to 9216 wasn't a problem (assuming your switch can handle it).
> Forced at 100 however, it wouldn't exceed 1500+overhead, which breaks
1500
> unfragged inside an MPLS VPN.

just following-up on this old thread (and for the archives):

I just got hold of an NPE-G2, and I can't reproduce this, a 9126 byte
MTU works just fine, no matter which speed I set the port to:

Cisco IOS Software, 7200 Software (C7200P-P-M), Version 12.2(31)SB11,
RELEASE SOFTWARE (fc3)

Router(config-if)#do show run int gig0/2           
Building configuration...

Current configuration : 139 bytes
!
interface GigabitEthernet0/2
 mtu 9126
 ip address 1.0.0.2 255.255.255.0
 media-type rj45
 speed 100
 duplex full
 negotiation auto
end

Router(config-if)#do ping 1.0.0.1 size 9126 df-bit

Type escape sequence to abort.
Sending 5, 9126-byte ICMP Echos to 1.0.0.1, timeout is 2 seconds:
Packet sent with the DF bit set
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
Router(config-if)#


Can you show details of your test/config? Not sure if you've already
provided feedback to Rodney..

	oli