881 Router - How many Vlans are supported (Dhcp scopes)

[bl-dubai-uae]

Dear All!

After calling Cisco three times without response, I need to ask this most likely simple question right here.

How many vlans does a 881 router support? Will this be the same number for dhcp scopes?

Thanks for your time...

..hopefully you guys can sort it for me ;)

[acampbell]

Hi,

On every Cisco router platform each interface,sub interface & VLAN
uses a system reference point referred to as an Interface Desciptor Block.
IDB

Depending on processing power of each platform determines the number
of IDBs the router platform can support.

On all IOS version referred to in the documentation a Cisco 881
can support up to 300 IDBs

The router has physically 5 interfaces (4 x LAN + 1 x WAN)

300 - 5 = 295

So you shouldin theory be able to build 

295/2 = 147 VLANs & 147 SVIs

Remember a VLAN uses 1 IDB & an SVI uses 1 IDB

See this link for more info.

http://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-software-releases-122-mainline/15096-idb-limit.html#max_no_interfaces

Hope this helps
Regards
Alex

[bl-dubai-uae]

Hi Alex,

thanks for the link, that explained a lot!

How about DHCP scope limitations? My understanding is that with every enterprise platform each possible vlan stands for one possible dhcp scope!? Right?

So I should be getting 147 possible DHCP scopes?

Basically I am only needing a small DHCP server which supports 100+ DHCP scopes.

Thanks again.

Your help is highly appreciated!

Björn

[Leo Laohoo]

880 routers can support up to EIGHT (8) VLANs.

[bl-dubai-uae]

Thanks!

Any suggestion for a router or a compact switch to offer 50+ Vlans / DHCP scopes?

Cheers

Björn
 

[Leo Laohoo]

If you want a small router which can support >50 VLANs then you'll have to start with a 1900 router.  

As to a DHCP scope support of >50, I can't tell.  The largest I've seen is about >20 DHCP scopes.  This is an inefficient method you are doing.  

If you really want a low-cost DHCP "server", then think about getting a Raspberry Pi.  You can get one for <US$100 and you can power up the Raspberry Pi using an iPhone charger (1 watt).  Alternatively, you can use a BeagleBone.  Both are Linux based and can fit at the palm of your hand.