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You hit everything except the first thing I would check. Are the ports on
the switch configured with the same speeds, packet size, etc. as the HMC is
expecting. I'd suggest hard coding them if the negotiate does not seem to
work.

--
Jim Oberholtzer
Agile Technology Architects


-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of
Taylor Hammerling
Sent: Wednesday, May 11, 2016 2:31 PM
To: midrange-l@xxxxxxxxxxxx
Subject: ARP issues with HMC and iSeries

We have an HMC which we have been having issues talking to.
This all started when we moved offices, although everything is plugged into
the core exactly like it was in our old office.

Here is what I have found so far.

1) When attempting to ping 192.168.1.218 from vlan6 (our user vlan), the
first reply was successful, but the other three timed out, as did subsequent
tries.

2) when attempting to ping 192.168.1.218 from vlan4 (our server vlan) it
appears to be very hit or miss.

3) when attempting to tracert to 192.168.1.218 from vlan6 (our user vlan),
the first hop it hits is 172.18.6.1 (which is the gateway of vlan 6 and the
vlan 6 interface on the core)
The second hop is 192.168.1.213 (which is very odd)

4) when attempting to tracert to 192.168.1.218 from vlan4 (our server vlan),
the first hop it hits is 192.168.1.213 (which is very odd)

5) when checking the arp on a windows server, I see (This is what it should
look like)
Interface: 192.168.1.131 --- 0xb
Internet Address Physical Address Type
(unimportant information redacted)e
192.168.1.213 5c-f3-fc-eb-37-3f dynamic
192.168.1.218 00-14-5e-fa-f9-4a dynamic

---sometimes, and this other times (this is what it looks like when we are
having issues communicating with the HMC)

Interface: 192.168.1.131 --- 0xb
Internet Address Physical Address Type
(unimportant information redacted)
192.168.1.213 5c-f3-fc-eb-37-3f dynamic
192.168.1.218 5c-f3-fc-eb-37-3f dynamic

6) when I checked the arp on the core, I see CORE# show arp

IP ARP table

IP Address MAC Address Type Port
--------------- ----------------- ------- ----
(unimportant information redacted)
192.168.1.213 5cf3fc-eb373f dynamic 1/15
192.168.1.215 5cf3fc-eb373f dynamic 1/15
192.168.1.218 5cf3fc-eb373f dynamic 1/15

192.168.1.213 is a physical ethernet line on the P7
192.168.1.215 is a virtial ethernet line on the P7
192.168.1.218 is a physical ethernet line on the rw-ihmc

The gateway for vlan6 and the vlan6 interface on the core is 192.168.6.1 The
gateway for vlan4 and the vlan4 interface on the core is 192.168.1.1.

I have cleared the arp cache on both rw-app2 (vlan 4 server) and the core
switch.

I set up port mirroring on the core by running the following commands conf t
mirror 1 port 1/1 int 1/15 monitor all both mirror 1 no-tag-added This will
cause traffic on port 1/15 (the iSeries vlan 4 interface on the core) to be
mirrored to port 1/1. I plugged in my laptop into port 1/1, started a packet
sniff, cleared the arp cache on the core, pinged 192.168.1.218, and then
inspected the packet sniff.
I found that the vlan 4 NIC of the iSeries was replying to the "who has" ARP
requests for both 192.168.1.213 and 192.168.1.218, even though it only has
192.168.1.213 on it!

I then took the HMC offline (unplugged it from the core) cleared the ARP
cache on the core switch, tried to ping 192.168.1.218 from the core, ran a
show arp on the core,

Same results as before, the ARP cache on the core shows both 192.168.1.213
and 192.168.1.218 as having the same MAC address, and being plugged into
port 1/15

Then I changed the IP address of the HMC to 192.168.1.214 cleared the ARP
cache on the core switch pinged 192.168.1.214 from the core switch did a
show ARP

and it's showing the exact same thing as initially (with the modified IP
address). 192.168.1.213 and 192.168.1.214 in the ARP cache both have the
same MAC address and port number 1/15

At this point I'm feeling like there has to be some IBM specific piece of
software or configuration I'm missing.

Thanks in advance for any help you can provide me!


Taylor Hammerling
IT Manager | RateWatch [cid:image001.jpg@01CF54C9.F7AC2F10]
<https://www.linkedin.com/company/ratewatch?trk=top_nav_home>
[cid:image002.jpg@01CF54C9.F7AC2F10]
800.348.1831 x4302 |
taylor.hammerling@xxxxxxxxxxxxxx<mailto:taylor.hammerling@xxxxxxxxxxxxxx> |
rate-watch.com<http://www.rate-watch.com/>
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