"unsupported" features in IOS ("mpls mtu") (was: Re: [c-nsp] High Availability PoP Design)

[Rodney Dunn]

I think this was the thread for the MPLS MTU changes on 12.2S.

We goofed in that we allowed the MPLS changes in before the driver
code team had their changes in. To fix it we are changing the
driver code to allow user settable MTU via:

CSCsc62963
Internally found enhancement defect: Assigned (A)
Have configurable MTU Range 1524 -1548 on PA-1FE and PA-2FE

The goal is to get it in 12.2(28)SB which will be the CCO
release that consolidates the platforms (72xx, 73xx, 10k, etc.).

Rodney

On Mon, Nov 07, 2005 at 07:30:40AM +0100, Johannes Resch wrote:
> hi rodney,
> 
> On Fri, November 4, 2005 20:06, Rodney Dunn said:
> > On Fri, Nov 04, 2005 at 07:44:41PM +0100, Gert Doering wrote:
> >> hi,
> >>
> >> On Fri, Nov 04, 2005 at 12:31:21PM -0500, Rodney Dunn wrote:
> >> > We support 1500 byte ip headers on those PA's +
> >> > 6 labels (24) bytes.
> >>
> >> So if I understand this correctly, "mpls mtu 1524" will still work on
> >> FE ports on 7200?
> >
> > Yes.
> 
> maybe you could comment on the output below? you may also want to read
> case SR #602143087, which is directly related to the problem.
> 
> disclaimer: I know that this is from an unsupported engineering image. but
> after opening a case with CTAC, they confirmed (see TAC case notes) that
> this behaviour will stay in subsequent official 12.2S releases, and will
> also be introduced in other trains (12.3).
> 
> I'd appreciate to hear your view on this, maybe there has been some
> misunderstanding.
> 
> Router#sh run int f1/0
> Building configuration...
> 
> Current configuration : 105 bytes
> !
> interface FastEthernet1/0
>  ip address 192.168.0.1 255.255.255.0
>  duplex full
>  no clns route-cache
> end
> 
> Router#conf t
> Enter configuration commands, one per line.  End with CNTL/Z.
> Router(config)#int f1/0
> Router(config-if)#mpls mtu 1508
> % Please increase interface mtu to 1508 and then set mpls mtu
> 
> 
> Router#sh ver
> Cisco IOS Software, 7200 Software (C7200-P-M), Experimental Version
> 12.2(200508]
> Copyright (c) 1986-2005 by Cisco Systems, Inc.
> Compiled Fri 16-Sep-05 12:49 by sheroork
> 
> ROM: System Bootstrap, Version 12.1(20000710:044039) [nlaw-121E_npeb 117],
> DEVEE
> BOOTLDR: 7200 Software (C7200-BOOT-M), Version 12.0(24)S, EARLY DEPLOYMENT
> RELE)
> 
>  Router uptime is 4 minutes
> System returned to ROM by reload at 06:10:15 UTC Mon Nov 7 2005
> System image file is "disk1:c7200-p-mz.15thsept"
> 
> Cisco 7206VXR (NPE400) processor (revision A) with 491520K/32768K bytes of
> memo.
> Processor board ID 30468560
> R7000 CPU at 350Mhz, Implementation 39, Rev 3.2, 256KB L2 Cache
> 6 slot VXR midplane, Version 2.7
> 
> 
> best regards,
> -jr