EOBC0/0 cause Backbone 6506 ,core 6506 and one C4510R cpu high

Unanswered Question
Sep 7th, 2008

when C6506 rises high in cpu utilization intermittently, we could see EOBC 0/0 interface higher CPU uitilization and data flow on this interface at that time. What kind of traffic would flow in /out EOBC0/0 at that time? Right now it is runing version is 12.2(18)SXF12a on backbone C6506 and core C6506 two routers.

I have this problem too.
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justinchiou Mon, 09/08/2008 - 01:17

Hi Giuseppe:

The following is show module message on core-6506.

------------------ show module ------------------

Mod Ports Card Type Model Serial No.

--- ----- -------------------------------------- ------------------ -----------

1 24 CEF720 24 port 1000mb SFP WS-X6724-SFP SAD111302J2

5 2 Supervisor Engine 720 (Active) WS-SUP720-3B SAL1114KMWT

Mod MAC addresses Hw Fw Sw Status

--- ---------------------------------- ------ ------------ ------------ -------

1 001b.2a4e.88a6 to 001b.2a4e.88bd 2.5 12.2(14r)S5 12.2(18)SXF1 Ok

5 0017.9568.bf14 to 0017.9568.bf17 5.3 8.4(2) 12.2(18)SXF1 Ok

Mod Sub-Module Model Serial Hw Status

---- --------------------------- ------------------ ----------- ------- -------

1 Distributed Forwarding Card WS-F6700-DFC3B SAL1114KLGV 4.6 Ok

5 Policy Feature Card 3 WS-F6K-PFC3B SAL1114KP5J 2.3 Ok

5 MSFC3 Daughterboard WS-SUP720 SAL1114KQV6 2.6 Ok

Mod Online Diag Status

---- -------------------

1 Pass

5 Pass

Giuseppe Larosa Mon, 09/08/2008 - 01:35

Hello Justin,

EOBC Messages

This section contains Ethernet out-of-band channel (EOBC) messages.

these are messages of management inside chassis.

Do you see any error message related to EOBC ?

like the following


But you have said that three devices are involved in the problem so an hardware failure is unlikely.

There isn't a second supervisor on chassis.

So the EOBC can be used only to upgrade the CEF table on the DFC of linecard and it is a DFC 3B aligned with sup 720 3B.

Try to verify if any routing protocol is recalculating too frequently so triggering a massive CEF update

Hope to help


justinchiou Mon, 09/08/2008 - 01:58

Hi Giuseppe:

I already checked log , it's no any error message for EOBC interface and no interface is up/down at that time. It should not recalculate in routing update, then trigger mass CEF update. I am not sure it is "Cat6k boxes should not be reachable via 127.0.0.x addresses" or not. I could not encounter the real situation like web site says 6500 could reach via

Giuseppe Larosa Mon, 09/08/2008 - 02:39

Hello Justin,

127.0.0.x are the ip addresses used for inter -module communication in the chassis and are actually loopback addresses.

127/8 is reserved for loopback addresses: addresses used inside a node and not to be seen outside the node itself.

Hope to help



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