network backbone advice

[Disease]

Very interesting read so far, I have some questions if someone would be kind enough to answer:)

 

At the moment my core switches are layer 2 just linked together with no real rhyme or reason with severs plugged into different switches along with random network sockets around the school ( inherited network). I wish to improve this because as we have expanded, the network has begun to slow down.

 

At the moment servers go into one of the core switches which link to outlying layer 2 switches and then feed out to the sockets, most of these links are single fibre links with some being cat 5e. All the fibe is gig with gig media converters at each end and all have redundant pairs.

 

Am I right in taking the following approach to improve my network structure or have I misunderstood points of this thread.

 

 

I want to have a single 48 - port Layer 3 core switch.

Into this switch I will plug all my main fibre links using link aggregation and utilising the redundant pairs to form a 2 gig fibre backbone. I would also utilise bonding the dual network connections on my main servers to increase throughput and put those into the layer 3 core switch as well. Non main servers would go into the core switch as a single connection. This would use up 35 of the 48 available ports.

 

All outlying switches would be Layer 2 and then feed to the rooms.

 

Does this sound right?

 

Also if I connect other layer 2 swicthes that are in my main cabinet to the core switch would I connect them in with a single cat5 cable or should they be trunked in as well?

 

I was thinking of this switch as my core?

 

Support for 3Com® Switch 5500G-EI 24-Port (3CR17250-91) - Features & Benefits

 

Thanks in advance

Edited June 26, 2009 by Disease

[SYNACK]

I want to have a single 48 - port Layer 3 core switch.

Into this switch I will plug all my main fibre links using link aggregation and utilising the redundant pairs to form a 2 gig fibre backbone. I would also utilise bonding the dual network connections on my main servers to increase throughput and put those into the layer 3 core switch as well. Non main servers would go into the core switch as a single connection. This would use up 35 of the 48 available ports.

 

All outlying switches would be Layer 2 and then feed to the rooms.

 

Does this sound right?

Sounds good, with a layer 3 switch you can also implement routing which will decrease the broadcast domain and make more efficient use of the existing links. If you are doing this make sure that you get a L3 switch with L3 switching ability which is distinct from and much faster than L3 routing.

 

Also if I connect other layer 2 swicthes that are in my main cabinet to the core switch would I connect them in with a single cat5 cable or should they be trunked in as well?

 

Trunk these as well to allow for faster traffic flow between them, this also provides redundancy if one link fails.

 

I was thinking of this switch as my core?

 

Support for 3Com® Switch 5500G-EI 24-Port (3CR17250-91) - Features & Benefits

 

That looks good, it only has 4 sfps so you would only have the option of two teamed fibre links without grabbing an extra 10GB fibre module. You can get a stackable one that would go with it with room for 24 sfps though if you needed to. It does have L3 switching also which provides insane performance benifits over routing and looks to have free firmware upgrades and all of the generally expected features including stacking to extend the core.

 

I can't vouch for the quality or not of the hardware itself as I have not dealt with the 3com stuff for quite a while but it does look like a solid building block to build your network around.

[localzuk]

I'd dissagree with that change, I thought the same at first but if you have a look at the key the links are stack links. These run at the very least at 10GB and so are much better suited to the duty than a trunked solution in this situation.

 

That depends if the OP is sticking with 3com stacking switches I suppose. Personally I wouldn't touch them, but that's a personal choice.

 

Also, it depends on the switch - it may not be 10GB or more...

[SYNACK]

Also, it depends on the switch - it may not be 10GB or more...

 

Your right, if they are really old ones the link may be slower but you would not be able to get a faster link by using aggregated links as the limitation is based on the switching fabric and the software in the device. Besides using link aggregation would take up a large chunk of ports and for the moment the existing setup works.

 

In the future if they changed to a different type of switch for the core or one with a different stacking interface I would recommend that they keep the stack together as it will behave very simmilar to a single switch and just aggregate a whole bunch of links from the new core onto the stack master. This would use far less ports than trunking to each and the stacking internals are usually much better at handleing through traffic due to their optimized interface and software.

[localzuk]

Your right, if they are really old ones the link may be slower but you would not be able to get a faster link by using aggregated links as the limitation is based on the switching fabric and the software in the device. Besides using link aggregation would take up a large chunk of ports and for the moment the existing setup works.

 

In the future if they changed to a different type of switch for the core or one with a different stacking interface I would recommend that they keep the stack together as it will behave very simmilar to a single switch and just aggregate a whole bunch of links from the new core onto the stack master. This would use far less ports than trunking to each and the stacking internals are usually much better at handleing through traffic due to their optimized interface and software.

 

Or just use a HP 5400zl series switch

[SYNACK]

Or just use a HP 5400zl series switch

 

If we are going to play the who's gear is better game why not just use one of these and be done with it:

Cisco Catalyst 6513 Switch - Cisco Systems

of course it would be rude not to have quad trunked 10GB fibre to each cabinet with such a core setup though so it would require a certain 'high' level of budget commitment

 

 

Back towards the topic for the moment it looks like the OP is budget constrained and is doing an initial upgrade and rationilisation of their network to make it as good as it can be within the constraints of budget and disruption.

 

This bit goes for Disease to, depending on network size a modular core switch may be a good long term goal if you do not already have one. Givent the OPs network a small modular is probably the best candidate if they were replacing the core.

 

Modular switches have a basic chassie which provides a bunch of high speed communication channels and power then takes modules. The primary module is a supervisor module which is the master of operations, these can support many networking tasks in raw hardware which makes them porongraphicly fast. They can have multiple supervisors to provide redundancy. Next up they have access modules which can be 48 port 1gb or 24 port sfp or many other combinations. This all works together as one highly redundany, very fast and generally very loud unit. They are not cheap and are definitely not right for every situation as it takes a large network for them to come into their own cost/benifit wise but in some circumstances they can be the answer.

Edited June 26, 2009 by SYNACK

[wesleyw]

Isn't that a little bit too slow?

 

Wes

[Disease]

 

 

 

That looks good, it only has 4 sfps so you would only have the option of two teamed fibre links without grabbing an extra 10GB fibre module. You can get a stackable one that would go with it with room for 24 sfps though if you needed to.

 

 

This is where you lost me , my fibre would be connected to the switch with cat5e from media converters so does the lack of SFPs matter? Should I change all my connections from media converters to Mini GBICs, would there much of a performance difference? Can I still trunk the fibre links if I do not use GBICs?

 

What about this switch from HP:

http://h10010.www1.hp.com/wwpc/uk/en/sm/WF06b/12883-12883-3445275-427605-427605-3296367-3296370.html?jumpid=reg_R1002_UKEN

 

Or could you recommend a 48 Port Layer 3 Switch, I have a Budget of 3k for the switch.

 

 

Thanks

Edited June 29, 2009 by Disease

[SYNACK]

I remember having to use media converters , If you continued using them then no the extra SFP ports would not be nessisary and yes you chould be able to still trunk ports via them.

 

Personally I find media converters to be a massive pain to manage due to the extra bulk, complexity and power usage. Using mini-gbic modules would probably only give you a small decrease in latency unless the current ones are lower grade. I find that the gbics are easier to manage as they require no external power, fit inside the switch and propperly report their acrual status through the switch interface.

 

You can have converters on one side of the link and gbics on the other which is what I had running for quite a while at one site before I could upgrade it.

 

The hp switch is go in the fact that it has four 10GB interfaces avalible which makes it more scaleable than the 3com and it also (I think - hp specs useless) has layer3 switching and probably a better warrenty.

 

If you already have 3com in your environment then the 3com one would integrate easier with your existing setup but will a little effort the hp should also integrate nicely.

 

The hp probably offers a better warrenty and a bit better scaleability for future usage with teh 10GB ports but featureset wise it is not that far from the 3com meantioned earlier.

[Disease]

Thanks for all the advice on this, I went with the 3com gear in the end compared to the HP it has a higher rate of packet transfer and slightly better features.