JUNIPER M7i CFLOW Sampling for L2 Vlans

Fri Apr 16 16:12:12 UTC 2010

> It is possible to get cflow working in a L2 way ?

Hi Giuliano,

The short answer is, unfortunately, no.

NetFlow v5 does not have any fields for Layer 2 information: http://netflow.caligare.com/netflow_v5.htm

Although NetFlow v9 does have such fields, you (a) only get NetFlow v9 functionality on a Juniper if you have a Services PIC installed and (b) are limited by the NetFlow v9 templates that JUNOS implements.  See the section titled "Fields Included in Each Template Type" for a description of each NetFlow v9 template at http://www.juniper.net/techpubs/en_US/junos9.5/information-products/topic-collections/config-guide-services/services-configuring-flow-aggregation-to-use-version-9-flow-templates.html.

Juniper supports sFlow (which would give you L2 info) on their EX switches, but not on their routers.  Perhaps when/if IPFIX support comes along, you might be able to get what you are looking for.

You could use port mirroring or an optical tap with various open-source tools running on a Unix host to do the kind of monitoring you are looking for.

Cheers,
-Chris

On Apr 16, 2010, at 11:52 AM, GIULIANO (UOL) wrote:

> People,
> 
> Good afternoon,
> 
> We have a curious situation in a client's environment.
> 
> It has a M7i router with 2 IQ2E (4 GE) PICs.
> 
> It wants one of its PICs plugged into a L2 switch (802.1Q Trunk Mode)
> and the another one plugged (via 1 giga of 4 ports only) to another L2
> switch.
> 
> 
>          M7i
>        /     \
>     S1        S2
> 
> 
> Both Giga ports are simpled configured like:
> 
> nterfaces {
>    ge-0/0/0 {
>        vlan-tagging;
> 
> nterfaces {
>    ge-0/1/0 {
>        vlan-tagging;
> 
> 
> L2 Trunk Ethernet only without L3 configuration.
> 
> It is possible to get flow information about the encapsulated vlans
> (10,20,30,40, etc) inside the trunk traffic ? ... without configuring ip
> (4 or 6) or creating vlan interfaces ?
> 
> It is possible to get cflow working in a L2 way ?
> 
> Does anyone has configured it before using JUNIPER ?   Can you send or
> point to me some samples of configuration ?
> 
> Thanks a lot,
> 
> Giuliano
> 
> 
> 
> 	
> 
> 

--
Chris Tracy <ctracy at es.net>
Energy Sciences Network (ESnet)
Lawrence Berkeley National Laboratory