Catalyst 6500 BUS EoBC channel

[Alexey Stytsenko]

Good day, folk.

In  "How to display the EOBC error counters in the Catalyst 6500 series switches and a definition of the EOBC interface" document here on support forum stays that

The Ethernet Out of Band Channel (EOBC) is a  half duplex channel that services many functions, which include the  Simple Network Management Protocol (SNMP) and the packets that are  destined for the switch. 

Previously i were thinking that EoBC used only for SCP  and SLP protocol. In addition i found other article (but not on cisco site, heh) where stays that

 The Results bus is a       control plane, while the C (EoBC) bus is more of an       "admin plane", thus you will never see data       packets (such as CDP, SNMP, etc.) going over the R or C bus.

So there is a big contradiction between those two statements. Can somebody prove one of those and if first one right, what meaned under the

packets that are  destined for the switch

in it? SCP and SLP or other traffic as well?

Thanks in advance!

[InayathUlla Sharieff]

Hi Alexey,

The Ethernet Out of Band Channel (EOBC) is a half duplex channel that services many functions, which include the Simple Network Management Protocol (SNMP) and the packets that are destined for the switch. In order to ensure constant communication, some keep-alives run over the EOBC.

When several keep-alives are missed, it means communication is lost between the Application-Specific Integrated Circuit (ASIC) and the supervisor. In order to prevent this, the code contains a workaround that resets the EOBC when it sees that the messages do not increment constantly.

In switches, a counter called tx_head is constantly monitored. If this counter does not move, it is declared that the EOBC is stuck. At this point, the EOBC resets.

This problem usually occurs due to these circumstances:

• The EOBC channel fills with messages because of a storm of SNMP traffic. This occurs because it is a half duplex channel and is subject to collisions. When this happens, the EOBC can lack the time that is needed in order to transmit keepalives.
  
• A bad ASIC or a bad backplane exists. If this is the case, these messages appear constantly in intervals of three seconds or less.

In order to display information about the EOBC interface, use the show eobc command.

-

SCP is the protocol used for communication from SP to non-DFC line cards through Ethernet-out-of-Band Channel (EOBC) on the Catalyst 6500. . SCP or Keep Alive Polling failures could represent communication issues between the supervisor and line card.

Let me know if you required any further information on this and I would assist the same.

HTH

Regards

Inayath

*Plz rate all usefull posts.

[Alexey Stytsenko]

Ideed, I require futher information.

All you post here i already red, i even adduce link to this article in my initial message.

But even if take that SNMP pass over EoBC, I still wondering for - what type of packets/protocols use EoBC apart from SNMP, SCP and SLP?

Besides is there any possiblity to mirror traffic passed over EoBC?

[Alexey Stytsenko]

still actual