Dear Fernando ,
Don't confuse between "MPLS-aware Netflow" and "MPLS Egress Netflow
accounting" , both are two different features.
First one is usually used on P routers in order to do netflow accounting for IP
packets encapsulated in MPLS headers inside the provider backbone and it can
support up to three MPLS labels in the stack i.e A label stack can for example
contain 4 or 5 labels but net flow accouting can only account for three labels
which are assigned by the network admin via this command "ip flow-cache mpls
label-positions [label-position-1 [label-position-2 [label-position-3]]]
[no-ip-fields]
[mpls-length]".
Second one is used on PE routers in order to account for traffic being received
by the PE router labeled (one label or two in case PHP is disabled) and then
those labels are being stripped off in order to forward the packet to the CE
router. Usually this feature is used in order to analyze MPLS VPN traffic.
In the second feature , egress netflow command is applied on the PE VRF
customer interface. While in the first feature ingress netflow is enabled in
order to account for labeled packets while traversing the provider backbone.
In both cases CEF must be enabled on the accounted interfaces. In the first
feature netflow version 9 should be in use. I am not sure if there is any
restriction about netflow version for the second feature but i am almost sure
it will need version 9 too (didn't try it).
I hope it is clear now.
Hisham El-Ezaby
CCIE# 21190 (SP)
----- Original Message ----
From: Fernando Santos <[EMAIL PROTECTED]>
To: [email protected]
Sent: Tuesday, October 21, 2008 7:01:05 PM
Subject: [OSL | CCIE_SP] Netflow for MPLS
Hello all,
I have a question regarding Netflow and MPLS that I hope someone can help.
In search for clarification on this topic I ended up in some pages that I'll
include the URL.
http://www.cisco.com/en/US/docs/ios/12_2t/12_2t15/feature/guide/ft_nfsub.html
Based on this link, (besides the collector and version) to enable netflow under
an interface we use "ip route-cache flow" and to enable under a subinterface we
use "ip flow ingress".
Now my confusion arises when I look at both these links:
http://www.cisco.com/en/US/docs/ios/netflow/configuration/guide/cfg_mpls_netflow_ps6350_TSD_Products_Configuration_Guide_Chapter.html
http://www.cisco.com/en/US/docs/ios/12_1t/12_1t5/feature/guide/egress.html
In the upper one, to configure the MPLS aware netflow just the "ip flow
ingress" is mentioned. In the second link however, "mpls netflow egress" is
mentioned.
Although I notice that the first command is ingress and the second is egress,
what would be the say to use them if we got asked to configure mpls aware
netflow on some interfaces?
Should we look at the interface to see if the ingree/egress is labeled or not,
deciding which one to apply based on that?
What is your advice to approach this topic?
Thanks in advance.
Regards,
Fernando.
