Ask the Expert: Access LAN Switches (Cisco Catalyst 4500E, 3750-X, 3560-X, and 2960)

[ciscomoderator]

With Nikolay Karpyshev

Welcome to the Cisco Support Community Ask the Expert conversation. This is an opportunity to learn and ask questions about architecture and troubleshooting Access LAN Switches such as Cisco Catalyst 4500E, 3750-X, 3560-X, and 2960 with Cisco Expert Nikolay Karpyshev.

Nikolay Karpyshev is a Customer Support Engineer in the high touch technology support  team (HTTS)  at Cisco specialized in LAN Switching. Karpyshev supports the Cisco Switches Nexus 7000, Catalyst 6500, 3750, 3560, 4500, 2900, among others, and works as senior and escalation engineer. He was previously a part of Cisco Sales Associate program. He holds a specialist degree in Mathematics and Mechanics from Novosibirsk State University in Russia. Nikolay also holds these Cisco Certifications:  CCNP, CCSP, and CCDP.   

Remember to use the rating system to let Nikolay know if you have received an adequate response. 

Nikolay might not be able to answer each question due to the volume expected during this event. Remember that you can continue the conversation on the Network Infrastructure sub-community discussion forum shortly after the event. This event lasts through July 27, 2012. Visit this forum often to view responses to your questions and the questions of other community members.

[nkarpysh]

Hi Joseph,

The type of SFP to be used defines the type of fiber or to be more accurate the type of fiber you have to use due to environmental constraints defines the type of SFP. Thus as long as SFP on both size matches with fiber type/length, etc and as long as SFP on each particular side is compatible with the switch it is installed on - it does not care what is the transceiver used on the other side of the link. Thus SFP does not check the compatibility with remote transceiver as it pure L1 device.

There might be some other problem occurring in regards to link negotiation between products of different vendors but those are quite rare and usually are exception. So in terms of SFP - yes it should work.

Nik

[Yvon Darang]

Hi Nik

I have configured the following PBR on a cisco WS-C4510R-E with Supervisor Engine 6-E 10GE (X2), 1000BaseX (SFP) running IOS Version 12.2(52)SG

access-list 10 permit 172.18.120.0 0.0.0.255

!

!

route-map McGill permit 10

match ip address 10

set ip default next-hop 172.16.1.210

interface vl 120

ip policy route-map McGill

It ran well for 1 month then for no reason at all (No hardware change, no ios change) it stop working. Do you have any idea?

[nkarpysh]

Hi Yvon,

Well, I don't have any good idea as I don't have much experience with routing features on this platforms.However few steps I would recommend to do:

1. First please advise how you noticed that it is not working (interface statistics, sniffere's results, ACL hits (or no ACL hits), etc)

2. There is a defect in 12.2(52) and 12.2(53)SG when PBR is not honored in HW - so you may be hitting it.

CSCtc90702 cat4K SUP6 PBR not programmed in hardware

http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCtc90702

The bug is fixed in 12.2(53)SG2.


You can check it in more details with following commands:

show plat hard acl input entries vlan 120 type ipv4 all
 
 Search for following index in it:
 
 
Idx: 1 Hit: false FNH: false EV: true FlType: 1 / 3 Label : 2 / 16383 ToRouter : true / true Cos : 0 / 0 Tos : 0 / 0 Opcode : 0 / 0 IP Src : 172.18.120.0 / 255.255.255.0 <==========


 And scroll to the end of it for action index. It should look like:
 
 
ActIdx: 255 StatsIdx: 0 FwdIdx: (None, rep: 0) 

If you see the one like above it means that action is default and Null matching the symptoms of DDTS.
 
 You can check it in more details with:
 
 
show plat hardware acl input actions # ---------- # is number  after ActIdx: (e.g. 255)
 
 
 
 
 
Workaround for that is
The CLI "cef table output-chain build favor memory-utilization" can be used as a workaround, to override the default. However, this could have unforeseen and degenerative effects on convergence.
 
 
 
 So you can try above or even try the IOS which has a fix to see if it helps.

3. Enable following debug to see what is happening around policy "'debug ip policy'". You may want to increase the log buffer and direct debug output to it not to have much output on your terminal.

Those are steps I would recomend. Let me know if those helps or not.

P.S. Please note that this thread will be closed soon and you will not be able to put any updates. Thus you can open new Thread in LANSW for this and let me know via private message of it.

Nik

[Fraser Reid]

Hi All,

          I always have a problem when stacking the 3750x (building a new stack).

Every new switch that gets added to the stack has to have a Direct Connection to the stack master to be able to join the stack without starting up as a standalone.

Any pointers on this one ?

So far it had made no difference as to what IOS was present (12.x or 15.x) and they were all identical on all stacked and the added stack members.

This makes things tricky with stacks of more than 4 switches due to cable length that comes with the switches per default.

Thanks.

[nkarpysh]

Hello,

You can do stacking in to major ways:

Option1:

Option2:

So if you started with one of that in the begining you need to proceed with it. Thus if you started to connect top switch in stack with bottom one then you need to have longer cable.

However if you selected the first option from the begining you can just move one cable from the bottom switch to the new one and the last stack cable from new switch connect to one one which  had a connection with bottom switch before.

E.G. if you have 4 switches and adding 5 th one.

Before addition connections on 4th were:

4_1 --- 2_1 (first number is switch and second is port)

4_2 --- 3 _1

You the change it the following way:

4_2 --- 5_1

5_2 --- 3_1

And you still can maintain the shorter cables.

HTH

P.S. for reference:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/hardware/quick/guide/3750GSG3.html#wp53466

Nik

[Fraser Reid]

Hey Nik

My main problem was with the newly added switch not being able to join the stack unless it had a direct connection to the master Switch - and that is why i have to take option 2.

The top switch is always master in my stacks (to begin with) and without a Direct connection I was not able to get any switch to join in.......

Fraser

[nkarpysh]

Thanks Fraser,

Well - it does not look normal. One question - did you try to shutdown some switch in the middle and then re-enable it? By this emulating the situation when one switch fail and you replacing it. Will the switch after shutdown also fail to come up in stack as it also not connected to master? Is it possible to try that.

I would recomend opening TAC case to check that in more details as this can be related to some SW defect or HW problem.

Nik

[NeedNova]

Hi so i have a weird problem with my catalyst 3750.

So when I hook up my computer directly to the 3750 it doesn't provide internet to the computer

However, when I hook up an external 5 port switch to the 3750 directly, and then I hook up the computer to the switch that is hooked up to the 3750, it does provide internet.

I've been trying to fix this for a while, I need some help

If responded here, please email me at kdogic91@gmail.com.

Thanks!