Migrating Core routing from HP to Cisco 3750

[utawakevou]

Towards the end of last year, we did install 2 Cisco 3750 (stacked) and our plan is to have this as our Core router later. Got static VLAN's configured and is just currently it is just doing switching. We got a HP L3 swith currently doing core routing and inter-VLAN routing. We now want to migrate all the function from the current HP to the stacked Cisco 3750 L3. Would apprecaite any help in the step by step plan for this migration and configuration's on the Cisco end

Am planning to start off will a VLAN to test that and once it works properly then move to the other VLAN's.

Any help will be really appreciated

[utawakevou]

Any helpers out there ?

[Mohamed Sobair]

Hi,

You need the following:

1- Prepare and configure all VLANS on the Stack Switches.

2- creat a trunk link between the HP and the Stack Switches. (all Switches in transparent mode).

3- start Migrating per VLAN basis.

4- Take all the conections from HP to the Stack Switches

HTH

Mohamed

[utawakevou]

Thank you Mohammed for your post. We have already got 1,2 and 4 done. However we want to migrate the HP's role(core routing and interVLAN router) to the stacked Cisco 3750. At the moment we have already got 20 VLAN's including the default on the stacked Cisco L3 switch and also trunked to the HP 4204vl L3. My concern is converting it to do routing. We will then implement OSPF (currently on static routing), once we have migrate all the role from the HP to the Cisco

Any document will also be really appreciated

Once again thanks for hte heads up

[Jigar Dave]

1. To migrate HP's core and intervlan routing to Cisco - first enable "ip routing"

2. put cisco switch in VTP server mode and give it name as your organization i.e. ABC Corp. and create all vlans those are currently on HP switch

3. first pull some 2-3 cables from HP Switch to Cisco Switch and try to find that those VLANs are working fine or not - if they are fine - go with others step by step

hope this helps

- JD

[utawakevou]

As mentioned before, I have already got the VLAN's created in the Cisco stacked switch and currently in operation (live environment). Do I have to delete  and re-create it ? Why do I have to pull the cables ? I will still need that as I got sites connected via the HP box on different VLAN's. By the way we have 2 server rooms where server room 2 is where we have  the HP L3 swtich (currently core routing and inter-vlan router)and server room 1 in a seperate building connected via Fiber link is where we have the Cisco stacked L3 3750 (proposed Core router and inter-vlan router). Most of our building are connected to the HP L3 switch in server room 2 and all our servers are connected to Cisco stacked 3750 in server room 1. Attach herewith is a diagram depicting the setup

[ahmedchohan]

Hi

U don't need to renable the vlans. Just make the SVIs. On migration day, make sure you have all the vlans SVIs on the 3750 core, and all the vlans default gateway is the new 3750 core. Make the HP do just switching and remove all SVIs from HP. If you have any static routes on HP, use the same for 3750. Default route ?

First, make a temporary vlan, have host connect physicaly to that vlan. Make 3750 the core for only that vlan. and make sure all static routing and default routes are there on the 3750. Make sure this new temp vlan has access to all applications. internet everything. If it does, you can seamlessly migrate from hp to cisco

[Jigar Dave]

Hi utawakevou, Ahmed is right, but pls keep in mind below points

Answers

--> I have already got the VLAN's created in the Cisco stacked switch and currently in operation (live environment). Do I have to delete  and re-create it ? - No
--> Why do I have to pull the cables ? - No - I thought you will replace HP with Cisco L3 so told to do that. after seeing your setup, I got picture clear, you want to continue with HP and add Cisco in your environment, for this, do following steps.

1. connect HP and Cisco via trunk link and with encapsulation as dot1q

2. check that vlans those are on HP SW are exist on Cisco or not, if not - create them accordingly

3. let the cables in HP itself for those VLANs where you want them to route via HP SW

4. pull cables from HP SW and push them on Cisco for those VLANs which are new in your environments and you want them to route via Cisco only. - create SVIs first on Cisco L3 so they will get their route destination

5. ping HP mgmt IP from Cisco and vice versa so that you are confirmed that connectivity is there, check all vlans which are there on HP should be on Cisco

6. negative point - you can not enable pruning due to two different vendor switches.

HTH, pls rate helpful posts

Regards,
- JD

[utawakevou]

Thanks Ahmed and JD.

Q1 - When I create a Switch VLAN Interface say for vlan 52, will it not conflict with the current vlan 52 on the switch ?

Am a bit confused. Its just because I have already got these VLAN's configured and working on Cisco stacked 3750 but not as SVI's.On the stacked Cisco I have only one SVI i.e the default VLAN 1 which Im currently using for management and monitoring

interface Vlan1
ip address 192.168.3.40 255.255.255.0

Q2 - If I enable routing on the Cisco stacked 3750, will it not affect the VLAN's already created ? I got some routed VLAN's(will need SVI) and some standalone ones(doesnt propogate to the HP's) configure in this Cisco stacked 3750

JD,

I have already got step 1 & 2 and its working fine but without SVI's.

The diagram shows what we have right now and is working fine. Have got all the trunks and VLAN's propogate to both HP and the Cisco. All my servers are connected to the Cisco and working. My task is to migrate the role of routing from the HP to the Cisco. I dont think I have to pull cables:)

Hope you understand

[lamav · Accepted solution]

Uta:

Your 3750s are L2 switches now. That is why you only have one L3 interface for one vlan configured; it's the management interface. You need to enable routing on the 3750s for this migration. Makes sense?

You do that by entering the "ip routing" command. Now the 3750s are routers/L3 switches.(assuming you have the correct feature set loaded on the switch).

Then you create L3 interfaces for all the vlans you want to route. These vlans exist on the 3750, but only as L2 entities; there is no L3 interface to route packets from one vlan to another. So create the SVIs (L3 interfaces) and then you will be able to route between vlans. Makes sense?

And yes, you can have L3 interfaces for the same vlan on separate routers - why not? Make sure you give them different IP addresses and make sure you configure the subnet mask correctly, of course. And by the way, don't use vlan 1 for anything. Create a separate  managaement vlan and keep all user and management traffic off of vlan 1.  VLAN 1 is used to pass control plane information from one swithc to  another (CDP, PaGP, LACP, STP).

When you migrate one vlan at a time, you will need to change the default gateway information on the end hosts so that they point to the 3750s - this will allow you to decommission the HP switches for that particular vlan.

Hope this helps

Victor

[utawakevou]

Thanks Victor. Making sense now. One last question. Can you just confirm whether enabling ip routing and creating a L3 SVI for the same VLAN already created in the VLAN database will not affect other VLAN's in the database. For e.g I want to test this migration on VLAN 52. I have already got VLAN 52 and other VLAN's in the vlan database of the Cisco stacked as L2 entity then I enable routing then create a SVI for vlan 52

ip routing

interface Vlan52
ip address 192.168.52.1 255.255.255.0

The reason being, I just dont want to risk my network and other L2 vlans existed on the 3750 VLAN database not working when I do the above. This migration will be done on a live enviroment. Let me know

[lamav · Accepted solution]

Uta:

You can enable IP routing for an existing vlan on a switch and leave the other existing vlans as L2 entities.

HTH

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