Flow Control Help! 4507 Gigabit Connection to F5 BigIP

[btraister]

I have an F5 bigip 5100 connected to a 4507 on a gig fiber connection. We have been having some problems with retransmissions to devices being content switched over this connection. The show interface output shows that there are a lot of output drops. When I do a show int flow control this particular interface is showing up with DISAGREE under the flow control setting.

Do I need to configure send AND receive pauses?

[Kevin Dorrell]

Is this CatOS or IOS? Here is how you do it under CatOS:

http://www.cisco.com/en/US/products/hw/switches/ps4324/products_configuration_guide_chapter09186a00801c6251.html#1019996

And here is how you do it in IOS:

http://www.cisco.com/en/US/products/hw/switches/ps4324/products_command_reference_chapter09186a008037a05d.html#wp1301253

Each of these allows you to configure the flow control independently in each direction.

Hope this helps.

Kevin Dorrell

Luxembourg

[btraister]

It does not appear to matter which direction. Theoretically it can only help?

[Kevin Dorrell]

Just for completeness, here is the description of the show flowcontrol.

http://www.cisco.com/en/US/products/hw/switches/ps4324/products_command_reference_chapter09186a008037a05d.html#wp1301253

Are you getting "disagree" for both directions? I see from the document that they are listed independently. The "disagree" means they failed to negotiate, which probably means you will have to set them manually.

How do you have the flow control configured at the moment? Do you happen to know what the flow control and/or negotiation capabilities are in the other switch? Could you post the full results of the show?

Kevin Dorrell

Luxembourg

[btraister]

The interface I am most interested in right now is 3/17

Gi3/17 on disagree desired off 0 0

show interface:

switch4#sh int gi3/17

GigabitEthernet3/17 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet Port, address is 000b.5ffa.a6be (bia 000b.5ffa.a6be)

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseSX

input flow-control is off, output flow-control is off

ARP type: ARPA, ARP Timeout 04:00:00

Last input never, output never, output hang never

Last clearing of "show interface" counters 9w6d

Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 293764

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 19000 bits/sec, 31 packets/sec

5 minute output rate 219000 bits/sec, 58 packets/sec

5916682462 packets input, 4329589272385 bytes, 0 no buffer

Received 98563 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

3963 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 input packets with dribble condition detected

7035798567 packets output, 5987094706494 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out

switch4#

Its the output drops that I am most concerned with.

[Kevin Dorrell]

IMHO, I think you may have two distinct problems here: the "disagree" and the output drops, and I am not convinced they are related.

For now, let us look at the "disgree". I see that the show flowcontrol show the send flowcontrol administratively on, BUT the interface reports that output flowcontrol is actually off. Does that mean that you have configured it forced on at this end but nonegotiate? What are the configured flow control options at this end and at the other end?

Here are my reasons for thinking they may be two separate problems, but if anyone else can interpret it differently then please do chip in.

This interface believes that output flow-control is off. It therefore believes it is allowed to transmit frames as fast as the line will take them. Output flow-control is off, so output flow control cannot hold up the output queue. Now, it may well be that the other end believes it can do flow control, but in this case the lost frames would be seen as input queue drops or overruns at the other end, rather than output queue drops at this end.

I could be wrong, but I don't think there is any mechanism whereby if the remote end gets overrun with frames, it can signal the fact to the local end so that it can count them as output drops. So I don't think the output drops are anything to do with flow control.

It looks like this end is experiencing packets for transmission greater than 1 Gbit for bursts of more than 40 packets - the size of the output queue. At this point you might consider doing WRR QoS.

But I am aware that this does not seem to fit the bill either. I am guessing this is a WS-X4418 card, for which Gx/17 is an oversubscribed port. So I don't see how the backplane can feed it at more than 1 Gbps anyway. Do you see anything similar on the other ports that share the same backplane connection, i.e. G3/15, G3/16, and G3/18 ?

Kevin Dorrell

Luxembourg

[nehatsadriu]

My name is Nehat i'm new in this froum and i wanted to see if somebody can help me?

I have a switch cat 6506 and i have problems with IOS

in the begining I had this promt Router(boot)#

I was thinking that i have porblems with boot loader IOS. Traying to solve this problem i formatet the bootflash and now when i try to go to session 15 it tells me that "The module 15 is not installed"

How can i solve this problem

Thanks in advance

Nehat