ASK THE EXPERTS - Cisco Unified Computing Systems

[ciscomoderator]

Welcome to the Cisco Support Community Ask the Expert conversation. This is an opportunity to learn how to configure and troubleshoot UCS in various environments with Cisco expert Stephen McCabe. Stephen is a customer support engineer in Cisco’s Advanced Services group providing High Touch Technical Support. As part of the Data Center Networking team, he supports customers on the Cisco Unified Computing System and Cisco Nexus platforms. In addition, he serves as an escalations engineer for Cisco's Application Networking Services team supporting server/application load balancing, WAN acceleration, web caching proxy, and video and streaming media. Stephen holds a bachelor's degree in computer engineering from Ohio University.  He also holds CCIE #23917 certification in Security and is a Red Hat Certified Engineer, and is VMWare Certified Professional #71728.

Remember to use the rating system to let Stephen know if you have received an adequate response.

Stephen might not be able to answer each question due to the volume expected during this event. Remember that you can continue the conversation on the Unified Computing discussion forum shortly after the event. This event lasts through April 22, 2011. Visit this forum often to view responses to your questions and the questions of other community members.

[wu.kristi]

Hi Steve,

Do you have any pointers on how to configure a vPC peer-link on my Nexus? I would also be interested to know of any know issues with this configuration that I should be aware, like any bugs.

[stmccabe]

Hello Kristi,

So the vPC peer-link is used to synchronize state between two vPC peer devices (e.g., 5K-A and 5K-B).  The vPC link must be configured on a 10GE interface, and I would highly recommend atleast two interfaces bundled as a portchannel via LACP.. The vPC peer link leverages CFSoE (cisco fabric services) to synchronize state between vPC peers.

To add resiliency you can also configure a vPC fault-tolerant (FT) link, which is an additional mechanism to detect "liveness" of the peer. The vPC FT link can use any L3 port, but by default will use management network. One added note, the vPC FT link is used only when peer-link is down and does NOT carry any state information

For your vPC peer link the recommended port mode would be to 'trunk' allowing the links to support multiple VLANs including the access VLANs.

Recommended port-channel mode is Link Aggregation Control Protocol (LACP) for the following reasons:

• Dynamically react to runtime changes and failures
• Lossless membership change
• Detection of mis-configuration

*As a side note: vPC supports a maximum 8 ports in a port-channel in on-mode  and 16 ports with 8 operational ports/8 standby in a LACP  port-channel*

Many of your follow up questions can probably be answered by reviewing the following configuration guide:

http://www.cisco.com/en/US/partner/docs/switches/datacenter/nexus5000/sw/layer2/502_n2_1/Cisco_n5k_layer2_config_gd_rel_502_N2_1_chapter8.html

Before configuring vPC read the following guide on type1 and type2  consistency checks and understand how this works with the 5K running  vPC:

http://www.cisco.com/en/US/partner/docs/switches/datacenter/nexus5000/sw/operations/n5k_vpc_ops.html#wp424990

As for bugs, I always recommend customers read the release notes for a particular version of software (NXOS or any other) to understand what/if any vulnerabilities might exist for their particular environment with that particular code. 

Hth.  Best Regards.

[simon.geary]

Can you tell me if the C460 can boot from iSCSI using Windows 2008 R2?

I have read the interoperability matrix for this server and it implies that iSCSI boot is supported using Broadcom adapters without actually calling it out specifically.

http://www.cisco.com/en/US/docs/unified_computing/ucs/interoperability/matrix/r_hcl_C_rel1.12_C460_only_v3.pdf

As a seconary question, any idea if\when iSCSI boot will be avalable on the B-Series?

Thanks

[stmccabe]

Hello Simon,

That is correct, both the C250 and C460 with the Broadcom 5709 GE LOM supports iSCSI boot.  When you boot the C460 and launch the virtual media pointing to the Win2K8 OS, the server will kick of an Initialization of the iSCSI Initiator, and then scan for iSCSI nodes.  Once a valid target is discovered the OS will got through the install/boot process.

The B-series also has this capability with the with the Cisco M51KR-B/Broadcom BCM57711 Mezz card. All b-series blades support this card (b-200m1/m2, B-250's). The data sheet for the BCM57711 Mezz card can be found here:

http://www.cisco.com/en/US/prod/collateral/ps10265/ps10493/data_sheet_c78-624706.html

BR.

[bdowns838]

Hello Simon-

I have 5x UCS 5108 chassis running- all with 3x p/s N+1.  4 of them have 8x B200-M2 blades and work fine.  The last one has 6x B230-M1 which always causes a "thermal-problem" (F0411) at the chassis and fails to discover any servers.  Its not a chasis problem as I have swapped servers/chassis.  Am I missing a basic configuration rule or compatibility issue?

Thanks,

Bryan

[stmccabe]

Bryan,

Can I ask what firmware version you are running in your b-series?  There are some thermal related issues in 1.3.1x, that have been addressed in later 1.4.1x releases.

Thanks.

Stephen McCabe

[bdowns838]

1.3.1c.  I'll try the f/w update- thanks.

[simon.geary]

That is great news, thanks.

I also had no idea that you could currently do iSCSI boot using B-Series. Very good to know. Thanks again.

[Robert Burns]

It's worth noting that for iSCSI boot with B-Series the configuration is manual at this time.  The Broadcom iSCSI option ROM is not yet integrated into UCSM, but this is tentatively slated for the next UCSM release slated in the next few months.  After this release you'll be able to configure iSCSI boot targets as part of your Service Profile's boot policy.

Regards,

Robert