Regarding sub-interfaces

[Vijeth]

Hi,
The question I am asking may be very trivial, What are sub-interfaces ?
(Advantages, use cases, configuring sub-interfaces etc., )
Any pointers to previous posts or web resources would be much appreciated !!

Thanks,
Vijeth

[Mohieddin Kharnoub]

Hi

Subinterfaces are very common in Routing and Switching, used in so many areas.

Subinterfaces most common areas:

- Vlan subinterfaces: we have a L2 or L3 (without routing) switch with multiple vlans, and need routing between them, so we use an External router connected to this switch with one port, this port has no IP address, then we creat Subinterfaces on this port on the router, each interface related to one of the Vlans, and any client in this vlan will have the Gateway is this subinterface IP address.
So one ports with multiple interfaces (different IP addresses) and the router can make routing between them - Router on Stick.

- Frame relay subinterfaces, its a flexible solution for routing various protocols over partially-meshed frame relay networks, so the Router's physical interface can be logically divided into multiple, virtual subinterfaces. The subinterface may be defined as either a point-to-point connection or a multipoint connection.

I hope thats enough info.

Good Luck !!!

[Vijeth]

Hi,
Thanks for the response.
Are there any MIBs which would give me information on the sub-interfaces.

Thanks,
Vijeth

[Mohieddin Kharnoub · Accepted solution]

Hi
I think it depends on the Product it self, like Cisco's Routers, check this:
http://www.cisco.com/en/US/tech/tk648/tk362/technologies_q_and_a_item09186a00800c263d.shtml#qa3

The ProCurve Router, MIB files :
ftp://ftp.hp.com/pub/networking/software/J03_01-Mibs.zip

Check the IF.MIB file, it may support SNMP for Subinterfaces.

On Juniper, there are some specific commands to be enabled before SNMP link status processing on the subinterface.

Don;t forget to assign points :)

Good Luck !!!

[Vijeth]

Hi,
Could you point me to some documentation or web resource which has the complete information on sub interfaces and their usage, configuration etc.,

Regards
Vijeth

[Mohieddin Kharnoub]

Hi

Search in Juniper - Foundry - Cisco: "Subinterface" - "SNMP Subinterface" - "Subinterface MIB" ....

Some Forums for Network Management System has good information about this article like tek-tips.com.

If you can specify what exactly do you want, it may be helpful for us also.

Good Luck !!!