Re: Jumbo MTU issue on the FWSM

Have you tried bypassing jumbo frame?*

*jumbo-frame reservation

above command is in ASA.

Also it looks like there is a limit on the size of jumbo frame that FWSM can
support (I thinks something 8400?)
*
*
On Tue, Jan 11, 2011 at 11:18 PM, Sadiq Yakasai <sadiqtanko_at_gmail.com>wrote:

> Guys,
>
> Just came across something weird which I cant make out and a few searches
> haven't returned any meaningful results either. Guessing someone out here
> might be of help please.
>
> I am trying to configure jumbo MTU on my network. All other parts of the
> network are doing jumbo frames successfully but my FWSM (outside). The FWSM
> outside interface keeps fragmenting my IP packets (despite the configured
> large MTU on all its interfaces). This made me suspect the host 6509 doing
> something rather unpleasant. All IP and L2 interfaces are in fact
> configured
> with the right MTU size.
>
> So I came across a mismatch (from "show vlan mtu" output), see below. I
> then
> did a "show spanning-tree vlan 17" to find out an arbitrary port-channel
> interfaces in my spanning tree domain, which are neither configured nor
> accessible from any part of the host 6509 configuration. It appears that
> these arbitrary interfaces have a lower MTU, which might be responsible for
> the misbehavior I am seeing.
>
> Can someone please tell me what these do and if they are infact
> configurable?
>
> Thanks as usual!
>
> Sadiq
>
> ###################################################################
>
> Please see below:
>
> R601#
> R601#
> R601#sh span vlan 17
>
> VLAN0017
> Spanning tree enabled protocol rstp
> Root ID Priority 24593
> Address 0005.5f91.d800
> This bridge is the root
> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>
> Bridge ID Priority 24593 (priority 24576 sys-id-ext 17)
> Address 0005.5f91.d800
> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
> Aging Time 480
>
> Interface Role Sts Cost Prio.Nbr Type
> ------------------- ---- --- --------- --------
> --------------------------------
> Te9/3 Desg FWD 2 128.1027 P2p
> Po306 Desg FWD 3 128.1666 P2p Edge
> Po310 Desg FWD 3 128.1667 P2p Edge
> Po311 Desg FWD 3 128.1668 P2p Edge
>
> R601#
> R601#sh vlan mtu
>
> VLAN SVI_MTU MinMTU(port) MaxMTU(port) MTU_Mismatch
> ---- ------------- ------------- ------------ ------------
> 1 1500 1500 (Gi3/1 ) 9000 (Te9/3 ) Yes
>
> .....
>
> 17 8500(TooBig) 1500 (Po306 ) 9000 (Te9/3 ) Yes
> 18 - 1500 (Po306 ) 9000 (Te9/3 ) Yes
> 19 - 1500 (Po306 ) 9000 (Te9/3 ) Yes
>
> .....
>
> R601#
> R601#
> R601#
> R601#show mod
> R601#show mod
> Mod Ports Card Type Model Serial
> No.
> --- ----- -------------------------------------- ------------------
> -----------
> 1 6 Firewall Module WS-SVC-FWM-1
> SAD080803FL
> 2 6 Firewall Module WS-SVC-FWM-1
> SAD102105VN
> 3 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX
> SAL1106GBZ6
> 4 16 SFM-capable 16 port 1000mb GBIC WS-X6516-GBIC
> SAD0541041G
> 5 2 Supervisor Engine 720 (Active) WS-SUP720-3BXL
> SAL1103E6YD
> 6 6 Firewall Module WS-SVC-FWM-1
> SAD07170252
> 7 6 Firewall Module WS-SVC-FWM-1
> SAD071202GX
> 8 4 CEF720 4 port 10-Gigabit Ethernet WS-X6704-10GE
> SAL114998VQ
> 9 8 CEF720 8 port 10GE with DFC WS-X6708-10GE
> SAL1215LWZC
>
> Mod MAC addresses Hw Fw Sw
> Status
> --- ---------------------------------- ------ ------------ ------------
> -------
> 1 0003.feae.2b58 to 0003.feae.2b5f 3.0 7.2(1) 4.0(12)
> ShutDown
> 2 0017.95a3.e578 to 0017.95a3.e57f 4.0 7.2(1) 3.1(10)0 Ok
> 3 001a.6c97.cb34 to 001a.6c97.cb63 2.5 12.2(14r)S5 12.2(33)SXI3 Ok
> 4 00d0.c0d6.aba4 to 00d0.c0d6.abb3 3.0 6.1(3) 12.2(33)SXI3 Ok
> 5 0017.9444.4c1c to 0017.9444.4c1f 5.3 8.4(2) 12.2(33)SXI3 Ok
> 6 0002.fcbe.1634 to 0002.fcbe.163b 2.0 7.2(1) 3.1(10)0 Ok
> 7 0003.feab.3462 to 0003.feab.3469 1.1 7.2(1) 3.1(10)0 Ok
> 8 001c.585c.a368 to 001c.585c.a36b 2.6 12.2(14r)S5 12.2(33)SXI3 Ok
> 9 001d.4577.ae18 to 001d.4577.ae1f 1.4 12.2(18r)S1 12.2(33)SXI3 Ok
>
> Mod Sub-Module Model Serial Hw
> Status
> ---- --------------------------- ------------------ ----------- -------
> -------
> 3 Centralized Forwarding Card WS-F6700-CFC SAL1103EL86 2.1 Ok
> 5 Policy Feature Card 3 WS-F6K-PFC3BXL SAL1101D02A 1.8 Ok
> 5 MSFC3 Daughterboard WS-SUP720 SAL1103E9E9 2.6 Ok
> 8 Centralized Forwarding Card WS-F6700-CFC SAL11488UNG 4.0 Ok
> 9 Distributed Forwarding Card WS-F6700-DFC3C SAL1215M317 1.0 Ok
>
> Mod Online Diag Status
> ---- -------------------
> 1 Pass
> 2 Pass
> 3 Pass
> 4 Pass
> 5 Pass
> 6 Pass
> 7 Pass
> 8 Pass
> 9 Pass
>
>
> --
> CCIEx2 (R&S|Sec) #19963
>
>
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Received on Wed Jan 12 2011 - 01:04:10 ART