I agree, but what if I made all my ospf neighbour sessions to the routers by then and they peered up because the mtu was set to 1500. I definitely see the argument for changing it. I am providing an argument that we don't always need to. I know we should be looking ahead too and should see issues like that but I made lots of oversights due to pressure that cost me time just like that one.
Sent from my iPhone On 19/10/2012, at 12:28 PM, "Nick Bonifacio" <[email protected]> wrote: > What if you reload it when the proctor says "time for lunch!" ? > > Sent from my iPad > > On Oct 18, 2012, at 8:36 PM, Michael Davis - Webquor <[email protected]> > wrote: > >> Hi everyone - My question is "why would you do it?" if the question only >> asks you to ensure that two devices are CDP neighbours and that is it, >> then there is no need. >> The proctor at Sydney said that nothing outside the scope of the question >> was looked at or verified, and any extra configuration was not looked at >> providing it didn't interfere with the working configuration. So to save >> time I would leave it alone in that case. >> After being through the lab and having finished the config section with 30 >> secs to go, I can definitely see that the extra 5-10 mins taken to reload >> a switch/s and verify everything has come back up again could hurt. >> >> On 19/10/12 2:58 AM, "Bob McCouch" <[email protected]> wrote: >> >>> I would just do it! But a few minutes ago you said you wouldn't bother >>> unless the task mentioned a 1500-byte MTU so I was curious why you >>> lean that way vs the "safe" path. Just concern for the time of a >>> reboot? >>> >>> Bob >>> -- >>> Sent from my iPhone, please excuse any typos. >>> >>> On Oct 18, 2012, at 11:55 AM, Marko Milivojevic <[email protected]> >>> wrote: >>> >>>> It's a tough call to make really. The only correct answer must come >>>> from someone who's grading the lab. You know what needs to be done to >>>> be safe, so... why not just do it? >>>> >>>> -- >>>> Marko Milivojevic - CCIE #18427 (SP R&S) >>>> Senior CCIE Instructor - IPexpert >>>> >>>> On Thu, Oct 18, 2012 at 10:46 AM, Bob McCouch <[email protected]> wrote: >>>>> Ha, got me on that one! Yes, they'd need to specify the df-bit. >>>>> >>>>> Here's my question on interpretation then... Cisco's documentation on >>>>> QQ >>>>> tunneling states that you "must" bump the MTU: >>>>> >>>>> "Because the IEEE 802.1Q tunneling feature increases the frame size by >>>>> 4 >>>>> bytes when the metro tag is added, you must configure all switches in >>>>> the >>>>> service-provider network to be able to process maximum frames by >>>>> increasing >>>>> the switch system MTU size to at least 1504 bytes." (emphasis mine, >>>>> source >>>>> >>>>> http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/relea >>>>> se/12.2_46_se/configuration/guide/swtunnel.html#wp1001068) >>>>> >>>>> With this in mind, should we not assume that means we have to do it, >>>>> as the >>>>> config guide states it as a "must"? Just like MTU on PPPoE interfaces >>>>> -- >>>>> I've configured PPPoE dialer interfaces just fine without specifying >>>>> 1492 >>>>> MTU, but every time you see an official example config (or an IPExpert >>>>> DSG >>>>> solution as well!) they specify the MTU. I have assumed that means I >>>>> damn >>>>> well better do it too if I want points on such a task. >>>>> >>>>> What do you think, Marko? >>>>> >>>>> >>>>> On Thu, Oct 18, 2012 at 11:38 AM, Marko Milivojevic >>>>> <[email protected]> >>>>> wrote: >>>>>> >>>>>> On Thu, Oct 18, 2012 at 9:30 AM, Bob McCouch <[email protected]> wrote: >>>>>>> And if the grading script used "ping X.X.X.X size 1500" to test? :-) >>>>>> >>>>>> It would still work, since packets would be fragmented ;-). On the >>>>>> other hand, if they added "df-bit" to that command... another story. >>>>>> >>>>>> That said - unless the lab asks for 1500-byte payload, I wouldn't >>>>>> bother with it. Then again, if you think rebooting a switch won't take >>>>>> from your time, why not do it and not worry? Just keep in mind that >>>>>> changing "system mtu" will change IP MTU as well, which may have >>>>>> impact for routing protocols running on the switch. Luckily, you can >>>>>> fix that without a reboot with "system mtu routing" >>>>>> >>>>>> -- >>>>>> Marko Milivojevic - CCIE #18427 (SP R&S) >>>>>> Senior CCIE Instructor - IPexpert >>>>>> >>>>>>> >>>>>>> How about routing adjacencies? Might OSPF get tripped up by neighbors >>>>>>> agreeing they have 1500 byte MTU, but not being able to actually pass >>>>>>> 1500 >>>>>>> during LSADB sync? >>>>>>> >>>>>>> The devil is in those details. >>>>>>> >>>>>>> >>>>>>> On Thu, Oct 18, 2012 at 10:24 AM, Mills, Derek < >>>>>>> [email protected]> wrote: >>>>>>> >>>>>>>> Good questions Bob and I guess I need to know the answers. Perhaps >>>>>>>> my >>>>>>>> downfall is that I would configure it, run a few various pings to >>>>>>>> verify >>>>>>>> the reachability requirement, and would count those points when >>>>>>>> there >>>>>>>> are >>>>>>>> no other lab requirements indicating that an mtu change is >>>>>>>> warranted.**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> *From:* Bob McCouch [mailto:[email protected]] >>>>>>>> *Sent:* Thursday, October 18, 2012 9:17 AM >>>>>>>> *To:* Mills, Derek >>>>>>>> *Cc:* [email protected] >>>>>>>> *Subject:* Re: [OSL | CCIE_RS] Dot1q Tunnel and MTU**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> Hi Derek,**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> You say "most times" and you are correct. What are the times it >>>>>>>> wouldn't >>>>>>>> work? How might those times bite you either while configuring later >>>>>>>> elements of your lab, or how they might test your solution with a >>>>>>>> grading >>>>>>>> script?**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> We must learn the right thing to do, even if IOS doesn't warn you >>>>>>>> about >>>>>>>> something. :-)**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> ** ** >>>>>>>> >>>>>>>> On Thu, Oct 18, 2012 at 9:01 AM, Mills, Derek < >>>>>>>> [email protected]> wrote:**** >>>>>>>> >>>>>>>> Most times configuring dot1q tunnel in the lab will work just fine >>>>>>>> without >>>>>>>> changing the MTU on the switches. What is the opinion on whether we >>>>>>>> should >>>>>>>> change it or not? If there is a specific task requirement for it >>>>>>>> there >>>>>>>> is >>>>>>>> no question, but is it expected and standard procedure just to >>>>>>>> increase >>>>>>>> it >>>>>>>> ALL the time when you configure it? Will you miss the points if you >>>>>>>> don't >>>>>>>> configure it? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> DEREK MILLS >>>>>>>> <>< >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> --------------------------------------------------------------------- >>>>>>>> --------------------------------------------------------------------- >>>>>>>> --------------------------------------------------------------------- >>>>>>>> --------------------------------------------------------------------- >>>>>>>> ---- >>>>>>>> Anheuser-Busch InBev Email Disclaimer www.ab-inbev.com >>>>>>>> _______________________________________________ >>>>>>>> For more information regarding industry leading CCIE Lab training, >>>>>>>> please >>>>>>>> visit www.ipexpert.com >>>>>>>> >>>>>>>> Are you a CCNP or CCIE and looking for a job? Check out >>>>>>>> www.PlatinumPlacement.com >>>>>>>> >>>>>>>> http://onlinestudylist.com/mailman/listinfo/ccie_rs**** >>>>>>>> >>>>>>>> ** ** >>>>>>>> ------------------------------ >>>>>>>> Anheuser-Busch InBev Email Disclaimer >>>>>>>> www.ab-inbev.com<http://www.ab-inbev.com/disclaimer.cfm> >>>>>>> _______________________________________________ >>>>>>> For more information regarding industry leading CCIE Lab training, >>>>>>> please visit www.ipexpert.com >>>>>>> >>>>>>> Are you a CCNP or CCIE and looking for a job? Check out >>>>>>> www.PlatinumPlacement.com >>>>>>> >>>>>>> http://onlinestudylist.com/mailman/listinfo/ccie_rs >>> _______________________________________________ >>> For more information regarding industry leading CCIE Lab training, please >>> visit www.ipexpert.com >>> >>> Are you a CCNP or CCIE and looking for a job? Check out >>> www.PlatinumPlacement.com >>> >>> http://onlinestudylist.com/mailman/listinfo/ccie_rs >> >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
