Re: 3750x stack vs 4500-E

rtjensen4 · ‎06-04-2010

I was curious on the benefits of a large-chassis switch like the 4500-E vs a stack of smaller switches like the 3750Xs. I need to upgrade my access-layer switches and am debating replacing the existing 4506 (216 10/100 ports PoE) with a stack of 3750Xs. Currently they would only be layer-2 switches with maybe 5 VLANs in use.

Large Chassis:

Pros:

Only requires 2 power supplies to power everything vs individual power supplies per switch.

Superivsor hardware can be upgraded seperately

Various media types can easily be integrated by purchasing the necessary line card.

Cons:

Per-slot bandwidth restrictions.

Potentially wasted space if not all slots in chassis are used

If non-redundant supervisor fails, entire switch goes down.

Potentially higher initial cost.

Stack of smaller switches:

Pros:

Can easily add / remove stack members

Increased backplane bandwidth, 64gbps stacking ports on 3750Xs

Cheaper initial cost, can grow as needed.

If a switch fails, only devices connected to the switch go down and the rest of the stack still functions.

Cons:

Lots of physical hardware to manage

More power supplies to deal with.

Increase cooling needed(?)

Can anyone else add to this list? Keep in mind, this will be for my ACCESS layer, connecting to end-user PCs, so various media types aren't really a concern.

magnumpi83 · ‎06-04-2010

We are actually replacing our 3750 with 4500's. What we found with the 3750s is we had problems with the stacking ports in the back. Also, if the stack master switch in the stack with the 3750's fail there is no indication that the network is down except for user's calling. I think another reason we are switching is because we are upgrading our backbone to 10 gigabit connections which aren't found in the 3750s

rtjensen4 · ‎06-04-2010

That's interesting, I didn't think of that. Wouldn't you have the same problem with the 4500? If a line card fails, how would you know?

I know the 3750 switches don't do 10gig, but the new 3750X switches have an uplink module available that will support 10gb. The nice thing about the 3750X plaftorm is that they can be in the same stack as the class 3750 switches.

tprendergast · ‎06-04-2010

The early 3750s had some stack port issues, but they are resolved if you take time to carefully mount the stack cables. I also noted a lot of chinese knock-off stack cables were in the grey market, so make sure you order the Cisco originals... The knockoffs are cheaper but really wreak havoc on your network reliability.

The 3750s are great access layer switches, especially if you plan your patching around them. I had 3-drop cubicles, so we had ports a/b/c. Drop 1a mapped to port 1 of switch stack member 1, drop 1b mapped to port 1 of switch stack member 2, and drop 1c mapped to port 1 of switch stack member 3. You can print out an excel spreadsheet and always know which port is mapped where if you do it this way. If you lose a stack member, the user can just plug into another port and be fine 99% of the time, or you can quickly locate their next port and configure it.

You can use the EEM features to alert you if a stack member goes down. If you lost the supervisor in the 4500, you'd be toast. If you lose the master in the stack, another will take over and EEM will fire off and alert you to the dead member switch.

I've deployed a few dozen stacks of varying sizes. You can do quite a bit with them with some creative thinking.

MFloresG1 · ‎06-04-2010

I work for a very large ISP 90% of our access layer is 3750s from call center all the way to back office personnel - the 3750 has been working great for use we currently have them performing Layer 2 and Layer 3 functions (EIGRP) - being able to add 3750 members as needed is a great advantage over a modular switch - one huge drawback that 3750 have is QoS - We implemented QoS and incremental statistical data on show commands to verify QoS is not working - Cisco is currently working on finding the root cause to this problem so if you don't mind not being able to verify your QoS settings 3750 are a good choice over a modular switch.

I have added the output of a few show commands from one of production 3750 switches for you to see that incremental statistical data is not working when verifying QoS settings. Also I have included a few commands from our 4500 performing QoS but in here incremental statistical data works just fine...

hope this help you decide on the product that best fits your needs.

3750_1#show access-lists

Extended IP access list ALL-IP

10 permit ip any any

Extended IP access list REAL-TIME-VOICE

10 permit udp any any range 16384 32767

20 permit udp any range 16384 32767 any

Extended IP access list SIGNALING-VOICE

10 permit tcp any any range 2000 2002

20 permit tcp any range 2000 2002 any

30 permit tcp any any range 5060 5061

40 permit tcp any range 5060 5061 any

50 permit udp any any range 5060 5061

60 permit udp any range 5060 5061 any

3750_1#show policy-map interface

Vlan20

Service-policy input: MARK-DVLAN-20

Class-map: ALL-TRAFFIC (match-any)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: access-group name ALL-IP

0 packets, 0 bytes

5 minute rate 0 bps

Class-map: class-default (match-any)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: any

0 packets, 0 bytes

5 minute rate 0 bps

Vlan702

Service-policy input: MARK-VVLAN-702

Class-map: VOICE-BEARER (match-all)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: access-group name REAL-TIME-VOICE

Service-policy : POLICE-128K

Class-map: ACCESS-PORTS-SWITCH-1 (match-all)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: input-interface GigabitEthernet1/0/1 - GigabitEthernet1/0/48

Class-map: ACCESS-PORTS-SWITCH-2 (match-all)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: input-interface GigabitEthernet2/0/1 - GigabitEthernet2/0/48

Class-map: class-default (match-any)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: any

0 packets, 0 bytes

5 minute rate 0 bps

Class-map: VOICE-SIGNALING (match-all)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: access-group name SIGNALING-VOICE

Service-policy : POLICE-32K

Class-map: ACCESS-PORTS-SWITCH-1 (match-all)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: input-interface GigabitEthernet1/0/1 - GigabitEthernet1/0/48

Class-map: ACCESS-PORTS-SWITCH-2 (match-all)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: input-interface GigabitEthernet2/0/1 - GigabitEthernet2/0/48

Class-map: class-default (match-any)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: any

0 packets, 0 bytes

5 minute rate 0 bps

Class-map: class-default (match-any)

0 packets, 0 bytes

5 minute offered rate 0 bps, drop rate 0 bps

Match: any

0 packets, 0 bytes

5 minute rate 0 bps

3750_1#sh run int gig2/0/2

interface GigabitEthernet2/0/2

description To 1A-17D

switchport access vlan 20

switchport mode access

switchport voice vlan 702

priority-queue out

mls qos vlan-based

spanning-tree portfast

spanning-tree bpduguard enable

=================== END 3750 SWITCH =============================

=================== 4500 SWITCH =============================

4506_1#sh access-list

Extended IP access list REAL-TIME-VOICE

10 permit udp any any range 16384 32767 (1371529 matches)

20 permit udp any range 16384 32767 any (207944 matches)

Extended IP access list SIGNALING-VOICE

10 permit tcp any any range 2000 2002 (401488 matches)

20 permit tcp any range 2000 2002 any

30 permit tcp any any range 5060 5061

40 permit tcp any range 5060 5061 any

50 permit udp any any range 5060 5061

60 permit udp any range 5060 5061 any

4506_1#show policy-map interface

Vlan150

Service-policy input: MARK-DVLAN-150

Class-map: class-default (match-any)

34963241 packets

Match: any

34963241 packets

QoS Set

ip dscp default

Vlan715

Service-policy input: MARK-VVLAN-715

Class-map: VOICE-BEARER (match-all)

1579473 packets

Match: access-group name REAL-TIME-VOICE

QoS Set

ip dscp ef

police: Per-interface

Conform: 315894600 bytes Exceed: 0 bytes

Class-map: VOICE-SIGNALING (match-all)

401838 packets

Match: access-group name SIGNALING-VOICE

QoS Set

ip dscp cs3

police: Per-interface

Conform: 19291580 bytes Exceed: 0 bytes

Class-map: class-default (match-any)

34963241 packets

Match: any

34963241 packets

QoS Set

ip dscp default

Leo Laohoo · ‎06-05-2010

Currently they would only be layer-2 switches with maybe 5 VLANs in use.

Layer 2 only? How about the cheaper 2960S?

hobbe · ‎06-07-2010

There actually are some other things to consider also.

If you are using the stack as a Core then you might have other switches/stacks physically in remote areas that you might have problems securing the wires to.

The 3750X is capable of 802.1AE ie link encryption wich might be a nice feature.

You mentioned if a switch goes down, well depending on how you connect several stack groups you can have a great deal of redundancy with stacks and etherchannels to different members in the stack so you need not loose any switch/switch connections just because one switch goes down.

and yes providing you are monitoring your machines you will be able to get alarms if the stack looses a switch. Either via SNMP or Syslog.

The power cabeling in the 3750x looks realy nice (you can use the stack itself as a redundant powersupply.

However that said there are times when the whole stack will fail to be up.

Software errors causing reloads is one of them. (yes s*** happens but hopefully you tested the commands first on another 3750x with the same software)

software maintenance is another thing that will make the entire stack unusable for a short period of time. (reload time)

Reloads will of course stop all service from the stack during reload.

Spare units (parts) are cheaper to buy than a spare 4500 and so on.

if you have a spare 3750x or two then you can test commands and configurations with them and if you want to then you can educate yourself with them. and when needed they will replace a faulty switch in a stack faster then you can have any spare parts for the 4500 there.

All in all I realy like the 3750 series and I do feel that they should be able to give you better uptime on the network than a 4500 and more bang for the buck so to say.

HTH

rtjensen4 · ‎06-07-2010

I thought of another Pro for a stack of 3750X:

3750Xs can join a stack of 3750 switches, only at 32gbs ring, but they can work together. That means my existing 3750 stacks can be expanded as well.

Here's the list so far from the feedback I've gotten:

Large Chassis:

Pros:

Only requires 2 power supplies to power everything vs individual power supplies per switch.

Superivsor hardware can be upgraded seperately

Various media types can easily be integrated by purchasing the necessary line card.

Can upgrade firmware on individual line-cards independantly.

Cons:

Per-slot bandwidth restrictions.

Potentially wasted space if not all slots in chassis are used

If non-redundant supervisor fails, entire switch goes down.

Potentially higher initial cost.

Expensive / Difficult to keep spares on hand.

Stack of smaller switches:

Pros:

Can easily add / remove stack members

Increased backplane bandwidth, 64gbps stacking ports on 3750Xs

Cheaper initial cost, can grow as needed.

If a switch fails, only devices connected to the switch go down and the rest of the stack still functions.

3750Xs backward compatible with 3750 in a stack(Stackwise+ vs Stackwise)

Easier / cheaper to spare

3750X cross-stack Power

Multi-Chassis Etherchannel.

Cons:

Lots of physical hardware to manage

More power supplies to deal with.

Increase cooling needed(?)

Potential for stacking port issues.

L3 Port / QoS counters not always accurate (I actually opened a TAC Case on this once, its due to the fact that 3750s do most of their switching / routing in hardware)

dominic.caron · ‎06-07-2010

I got a large number of switchs (around 1000) and I'm migrating away from the standalone models. Cisco's standalone series are short lived if you compare them to the modular one and you can end up having 5 generations of switchs to support before the next upgrade cycle. We did a TCO study a year ago and found the 4500 to be a better buy.

rtjensen4 · ‎06-07-2010

What were the factors that made the 4500 better?

serato1 · ‎07-12-2010

A pro that may or may not apply to you. The redundant stack of 3750's is seen as a single switch. If your servers/network gear has redundant ports there is no need to run HSRP or VRRP in order to offer redundancy. Using the 4500's you will need to make sure that if you put a configuration on one chassis you need to do the same on the other one. Seems like a small item but in reality a lot of people forget to put their changes in both primary and secondary. One other pro I can think of is cable management. There just isn't a way to make a 4506+ with 48 port cards look pretty without a lot of work. There is also the issue of having to replace the chassis should that ever be necessary. Getting a 4500 out of a two post rack without a lot of spare cable length isn't a fun task.