[f-nsp] nRe: Multiple subnets on same VLAN

[Jethro R Binks]

In the past, we've simply done this (usually in the context off adding 
another IP subnet into a VLAN, but probably also when merging two VLANs 
with subnets too):

vlan 24
 ta e 1/1
 router-interface ve 24                                           

interface ve 24
 ip address 10.0.1.100/24
 ip address 10.0.2.100/24

Alternatively, in some cases I also have this sort of thing (ancient 
BigIron config):

vlan 2
 ta e 1/1 to 1/3
 ip-subnet 10.0.1.0 255.255.255.0 name S1
   static e 1/1 to 1/2
   router-int ve 2
 ip-subnet 10.0.2.0 255.255.255.0 name S2
   static e 1/1 to 1/3
   router-int ve 3

int ve 2
  ip address 10.0.1.100 255.255.255.0

int ve 3
  ip address 10.0.2.100 255.255.255.0

I can't really remember much about it now :)

I'm not familiar with the trick just below.

Jethro.


On Thu, 13 Nov 2014, Wilbur Smith wrote:

> Jose,
> 
> This is pretty easy on the MLX. This is also referred to as “Super 
> Netting”.
> 
> The trick is to create two separate VE interfaces, one for each subnet’s 
> default gateway, then assign both VE interfaces to the same VLAN. You 
> will need to create the VE first before adding it to the MLX’s VLAN.
> 
> Config would look something like:
> 
> Interface ve 100
> Ip address 10.0.1.100
> 
> Interface ve 101
> Ip address 10.0.1.101
> 
> Vlan 100
> Router-interface
> Ve 100
> Ve 101
> 
> Apologies for not being able to confirm the exact syntax; don’t have access to a router right now.
> 
> Wilbur
> 
> From: Charles Monson <monson at wins.net<mailto:monson at wins.net>>
> Date: Wednesday, November 12, 2014 at 6:15 AM
> To: "foundry-nsp at puck.nether.net<mailto:foundry-nsp at puck.nether.net>" <foundry-nsp at puck.nether.net<mailto:foundry-nsp at puck.nether.net>>
> Subject: Re: [f-nsp] Multiple subnets on same VLAN
> 
> Do you have “no route-only” on the physical interface(s)? I’ve had trouble with routing between multiple subnets on  a router-interface once and things started behaving normally after changing that.
> 
> - Charles
> 
> From: foundry-nsp [mailto:foundry-nsp-bounces at puck.nether.net] On Behalf Of José Santos
> Sent: Tuesday, November 11, 2014 6:53 PM
> To: foundry-nsp at puck.nether.net<mailto:foundry-nsp at puck.nether.net>
> Subject: [f-nsp] Multiple subnets on same VLAN
> 
> Hi,
> I'm needing to merge two subnets that were before in two diferent VLANs in the same VLAN (attached to one untagged ethernet port) in a MLX router.
> 
> I configured multiple IP subnets in the same router-interface and I'm experiencing a lot of network issues. I am now trying to configure the subnets, let's say 192.168.50.1/24<http://192.168.50.1/24>, 192.168.51.1/24<http://192.168.51.1/24> and 192.168.52.1/24<http://192.168.52.1/24> in distinct virtual interfaces belonging to the same VLAN, however I am not being able to accomplish this since only one router-interface is allowed.
> 
> I thought configuring them in different loopback ports and then configure multiple unnumered interfaces or trunk various VLANs but none of this ideas seem possible as well.
> Anyone knows how can I accomplish this and can provide a brief config example?
> Thank you in advance!
> 
> --
> Best Regards,
> José
> 

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Jethro R Binks, Network Manager,
Information Services Directorate, University Of Strathclyde, Glasgow, UK

The University of Strathclyde is a charitable body, registered in
Scotland, number SC015263.