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MARK BAKER
Enthusiast

san-port-channel question on 6248-FI

On a customer's UCS deployment, I saw that the 6248-FI had 4 FC ports for each VSAN (A and B). I see that they are not configured in san-port-channels and wondered why since I believed that would give them load-balancing capability. When I checked the connected NEXUS 5548 FC ports, I saw that each of the individual FC ports were passing traffic in both directions. I didn't expect to see this since they are not in a san-port-channel. I thought it may have been an auto san-port-channel, but that wasn't the case.

1. Are the individual FC links load-balancing using some type of FC multi-pathing? I saw mention of it, but don't know the details of it.

2. Is there a benefit of using a san-port-channel since the individual links appear to already be load-balancing?

Thank you,
Mark

2 REPLIES 2
padramas
Cisco Employee

Hello Mark,

Can you please share output from N5K that indicates load balancing among individual FC links ?

In addition to load balancing the traffic, san port channels offer link redundancy and aggregates the bandwidth.

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5500/sw/san_switching/602_N1_2/b_5500_SAN_Switching_Config_602N12_chapter_0111.html#con_1248420

http://www.cisco.com/en/US/docs/unified_computing/ucs/sw/gui/config/guide/2.1/b_UCSM_GUI_Configuration_Guide_2_1_chapter_0110.html#concept_27BF341DAC6441EDB93F363AA6284E23

Padma

Padramas,

At first I thought san-port-channel 2 was configured, but it doesn't look like it was ever completed. All of these FC ports on the 5500 connect to the same 6248-FI using the same VSAN. They are not members of any san-port-channel but appear to all be transmitting and receiving traffic. There's no san-port-channel configured on the FIs either.

fc2/1 is up   
    Hardware is Fibre Channel, SFP is short wave laser w/o OFC (SN)
    Admin port mode is auto, trunk mode is on
    Port mode is F, FCID is 0xa7aaa1
    Port vsan is 1201
    1 minute input rate 4368592 bits/sec, 546074 bytes/sec, 365 frames/sec
    1 minute output rate 1538928 bits/sec, 192366 bytes/sec, 277 frames/sec
      2694130638 frames input, 4442925329352 bytes

fc2/2 is up
    Hardware is Fibre Channel, SFP is short wave laser w/o OFC (SN)
    Admin port mode is auto, trunk mode is on
    Port mode is F, FCID is 0xa7aaaa
    Port vsan is 1201
    1 minute input rate 4317608 bits/sec, 539701 bytes/sec, 529 frames/sec
    1 minute output rate 6198560 bits/sec, 774820 bytes/sec, 875 frames/sec
      4203477442 frames input, 5435444223112 bytes

fc2/3 is up
    Hardware is Fibre Channel, SFP is short wave laser w/o OFC (SN)
    Admin port mode is auto, trunk mode is on
    Port mode is F, FCID is 0xa7aaad
    Port vsan is 1201
    1 minute input rate 9855624 bits/sec, 1231953 bytes/sec, 901 frames/sec
    1 minute output rate 5449880 bits/sec, 681235 bytes/sec, 889 frames/sec
      4987584426 frames input, 8195595883960 bytes

fc2/4 is up
    Hardware is Fibre Channel, SFP is short wave laser w/o OFC (SN)
    Admin port mode is auto, trunk mode is on
    Port mode is F, FCID is 0xa7aaae
    Port vsan is 1201
    1 minute input rate 1337344 bits/sec, 167168 bytes/sec, 117 frames/sec
    1 minute output rate 2957152 bits/sec, 369644 bytes/sec, 245 frames/sec
      2614211091 frames input, 4249643735980 bytes


-------------------------------------------------------------------------------
Interface  Vsan   Admin  Admin   Status          SFP    Oper    Oper    Port
                         Mode   Trunk                                   Mode  Speed  Channel
                                     Mode                                            (Gbps)
-------------------------------------------------------------------------------
fc2/1      1201   auto   on      up               swl    F       8    --
fc2/2      1201   auto   on      up               swl    F       8    --
fc2/3      1201   auto   on      up               swl    F       8    --
fc2/4      1201   auto   on      up               swl    F       8    --

Group  Port-      Type     Protocol  Member Ports
       Channel
--------------------------------------------------------------------------------
2      San-po2              FC      NONE     (D)  FC       --

Mark

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