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Router 16 NM VLANS

I plan to purchase a 16 NM for my router, then configure each of the 16 ports with their own VLAN and therefor subnets.

Then connect each of the Ports to another routers FA0/0 port which has multi clients attached to it on another subnet.

This will effectivly give me one router connected to 16 other router in a Hub-spoke formation.

Will this work and can anyone for see any problems?

I can do a Viso diagram if needed

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Router 16 NM VLANS

Hi there,

Why don't you convert the Ethernet ports to Layer3 ports not as layer 2 ports with VLANs, i think this would be optimum for your case, having each point-to-point connection in the same subnet (an interface on the hub with each of its spokes):

interface FastEthernet0/0

no switchport

ip address x.x.x.x y.y.y.y

HTH, please rate if it does,

Mohammed Mahmoud.

8 REPLIES

Re: Router 16 NM VLANS

Hi there,

First of all, what are you planning to reach, what is your design aim? Second are you planning to connect the routers in a back-to-back or using switches between them?

BR,

Mohammed Mahmoud.

New Member

Re: Router 16 NM VLANS

I have attached my proposed design.

Distance between the hub router and the spoke routers is limited to 100m.

Hub router will have static routes for each spoke subnet.

Re: Router 16 NM VLANS

Hi there,

It should be simple and work with you, but keep in mind when configuring the static routes to point to next-hops not to outgoing interfaces, or as a best practice point them to both next-hop and outgoing interface simultaneously.

And practically speaking don't let the cable exceed 80m, its ok to 100m though.

HTH, please rate if it does,

Mohammed Mahmoud.

New Member

Re: Router 16 NM VLANS

Didn't know that routes could be set via the interface. Only thought that you could use the next hop.

So your saying having a differnet VLAN for each of the 16 Ports will work ok?

Re: Router 16 NM VLANS

Hi there,

Why don't you convert the Ethernet ports to Layer3 ports not as layer 2 ports with VLANs, i think this would be optimum for your case, having each point-to-point connection in the same subnet (an interface on the hub with each of its spokes):

interface FastEthernet0/0

no switchport

ip address x.x.x.x y.y.y.y

HTH, please rate if it does,

Mohammed Mahmoud.

Silver

Re: Router 16 NM VLANS

Not on a NM-16-ESW you won't, this switch is actually using the router's CPU and config and does not support layer-3 on the ports.

You will need an NME-ESW which is essentially a stand-alone 3750 switch which will support layer-3 capabilities...

Re: Router 16 NM VLANS

Hi Richard,

I already have it working:

Router#sh diag

Slot 0:

FastEthernet Port adapter, 16 ports

Port adapter is analyzed

Port adapter insertion time unknown

EEPROM contents at hardware discovery:

Hardware Revision : 1.0

Top Assy. Part Number : 800-15156-01

Board Revision : E0

Deviation Number : 0-0

Fab Version : 03

PCB Serial Number : 00000000000

RMA Test History : 00

RMA Number : 0-0-0-0

RMA History : 00

Base MAC Address : cc00.0a04.f000

MAC Address block size : 17

Product (FRU) Number : NM-16ESW=

EEPROM format version 4

EEPROM contents (hex):

0x00: 04 FF 40 02 A9 41 01 00 C0 46 03 20 00 3B 34 01

0x10: 42 45 30 80 00 00 00 00 02 03 C1 8B 30 30 30 30

0x20: 30 30 30 30 30 30 30 03 00 81 00 00 00 00 04 00

0x30: CF 06 CC 00 0A 04 F0 00 43 00 11 FF FF FF FF FF

0x40: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

0x50: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

0x60: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

0x70: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF

Router#

!

interface FastEthernet0/0

no switchport

ip address 192.168.99.1 255.255.255.0

!

interface FastEthernet0/1

no switchport

ip address 192.168.100.1 255.255.255.0

!

interface FastEthernet0/2

!

interface FastEthernet0/3

!

interface FastEthernet0/4

!

interface FastEthernet0/5

!

interface FastEthernet0/6

!

interface FastEthernet0/7

!

interface FastEthernet0/8

!

interface FastEthernet0/9

!

interface FastEthernet0/10

!

interface FastEthernet0/11

!

interface FastEthernet0/12

!

interface FastEthernet0/13

!

interface FastEthernet0/14

!

interface FastEthernet0/15

HTH,

Mohammed Mahmoud.

Silver

Re: Router 16 NM VLANS

Actually, the switch is not performing the routing, you have essentially made the FastEthernet ports on the switch router ports. All packets processed on those interfaces are handled by the router's CPU, not the switch.

My point was that the NM-ESW modules *ONLY* support limited layer-2 features and all layer-3 functionality (no switchport, interface vlan x) is performed by the router.

Be *VERY* careful with this. Many people have made the assumption that these ports are line rate and that the switch processes the packets, both are *NOT* accurate. In fact, this is a quick way to *KILL* your router's CPU, depending on the router model.

Just want to be sure you understand the NM modules (lack) of capabilities. Note that the NME-ES modules are in fact completely separate 3750 class switches with their own cpu and IOS image. The NME-ES modules support line rate layer-3 features which do not impact the router's CPU unless packets are destined to the router or through the router. The NME-ES switches also support the full NAC/802.1x/802.3af PoE/etc. This is completely different than the older NM-ESW modules which actually use the routers CPU for everything other than the layer-2 switch fabric.

Also, the NM-ESW modules have a <100 Mb connection via the legacy PCI bus that is compatible with a 2600 or 3600 router's NM slot. The NME-ES modules have a GigabitEthernet connection to the new high-speed PCI bus in the ISR routers (2800/3800).

See the following URL for more info:

http://www.cisco.com/en/US/products/hw/modules/ps2643/products_qanda_item09186a00802c9e7a.shtml

Hope that clears things up...

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