Problem with two network cards!

[MAD_2]

We have configured two network cards on our HP-UX 11.0. One of the cards is a FastEthernet card 10/100 and the other is a Gigabit card.

Unfortunaly, after a router configuration change that took place this past weekend, it seems every request (telnet, FTP, rcp) coming from the server uses the slowest of the two cards.

Any ideas?

See the following (IP addresses changed):
# netstat -rn
Routing tables
Dest/Netmask Gateway Flags Refs Use Interface Pmtu
127.0.0.1 127.0.0.1 UH 0 243355887 lo0 4136
199.99.99.59 199.99.99.59 UH 0 3341383 lan1 4136
199.99.99.60 199.99.99.60 UH 0 4 lan0 4136
199.99.99.0 199.99.99.60 U 2 0 lan0 1500
199.99.99.0 199.99.99.59 U 2 0 lan1 1500
127.0.0.0 127.0.0.1 U 0 0 lo0 4136
default 199.99.99.5 UG 0 0 lan1 1500

[melvyn burnard]

So are htese two cards on hte same subnet? if so, htat is not a supported configuration, and can give weird problems.

[John Palmer]

Having two cards on the same subnet isn't supported. Why configure the slowest card? If you simply want two IP addresses then configure the first as normal then add the second with
ifconfig lan0:1

Regards,
John

[MAD_2]

Yes, the subnet mask is the same Melvyn! My question is, why was it working before?

[MAD_2]

What is the autonegotiation for in SAM? How does it work? What changes do I need to make so that the Giga card is primarily used instead of the 10/100 and can I make this happen without disrupting service?

[Chuck J]

Why don't you just configure the second LAN with another IP then shut it down, that way all traffic will go through the first card. Also, is everyone coming through to your server via a DNS name, if so make the IP of the gig card correspond to the DNS name.

Here's the command to shutdown the second NIC if required:

# ifconfig lan1:1 down

[John Palmer]

Autonegotiation is a facility where the NIC and the switch negotiate speed setting etc. It's not recommended, you're much better advised locking the speed settings at both ends of the connection.

As I indicated earlier, I'd only configure the fastest NIC. If you are looking for resilience then the standby card facility of MC/Serviceguard may be an option or you could possibly use Auto Port Aggregation (if you've got a compatible switch).

Regards,
John

[Sanjay_6 · Accepted solution]

Hi Adam,

It is not a good idea to have multiple network cards from the same system on the same subnet. What i would suggest is to put the netowkr cards in different subnets and then use the faster speed card ip subnet as the default router.

Hope this helps.

Regds

[MAD_2]

I went back through SAM's networking and communications and reset the GIGACARD, now it seems everything is taking place with the GIGACARD. I think it's probably best if I disable the 10/100 card, unless I can set up a different Subnet Mask for it.

See below:

GIGACARD:
==============================================
Card Name: lan1

IP Interface #: 0

Hardware Path: 0/10/0/0
Station Address (hex): xxxxxxx

Card Type: [ 1000Base-T ->]
Speed : [ 1000 ->]
Duplex Mode: [ FULL ->]
Autoneg: [ ON ->]

Internet Address: 199.99.99.59 [ Modify Host Name Aliases.. ]

Subnet Mask: 255.255.254.0 (optional)


10/100 CARD:
==============================================
Card Name: lan0

IP Interface #: 0

Hardware Path: 0/0/0/0
Station Address (hex): xxxxxxxx

Card Type: [ Fast Ether ->]

Autoneg: [ OFF ->]
Speed (million bps): [ 100 ->]
Duplex Mode: [ FULL ->]

Internet Address: 172.16.52.80 [ Add Host Name Aliases.. ]

Subnet Mask: 255.255.254.0 (optional)

[MAD_2]

Sanjay, once the Subnet is changed for the 10/100 card, how do I make the Gigacard's subnet the default? Thanks!

[John Palmer]

The very fact that you've changed the 100base card to a different IP address *will* make the 1000base the default.

Your users will presumably only be using the 199.99.99.59 IP address and the default gateway 199.99.99.5 is in the same subnet therefore they can only use the 1000base card.

The problem with having two NICS in the same subnet is that the system has two possibilities for outgoing connections and you can't be certain which one it will use.

Regards,
John

[Adam J Markiewicz]

Hi

To make it short and clear:
1. Listen to the John good advice (first one) and use only one interface in the same subnet. No choice for kernel - no problem for you. Two cards in the same network doesn't mean double transmission speed.
2. Look at the John good advice (the last one). What you did is you've changed the IP for the slower card. No, if you didn't change enything else, according to your previous routing:

If you want connection to: 199.99.99.x or 199.99.98.x (netmask is 255.255.254.0) it goes directly through faster card.

If you want connection to: 172.16.52.x or 172.16.53.x (netmask also 255.255.254.0) it goes directly through slower card. (And if it is not what is directly connected to your local network, you probably receive no answer).

Everything else is chosen to go through the default gateway, that is 199.99.99.5, which actually belongs to the net serviced by the faster card.

Think what you want to archive. Thats what you have now. If you don't belive me - check it with traceroute.

Hope I helped a bit.
Adam

[MAD_2]

Thank you everyone for you participation and your responses. I am sorry but I think I created a little confusion with one of my last postings. In one of my previous replies I meant to say I reset the gigacard IP but I never changed IP addresses for either of the cards. The IP addresses were always different, I just forgot to replace the real IP on my example with a fictitious one. Here is the corrected scenario of what I had posted:


GIGACARD:
==============================================
Card Name: lan1
IP Interface #: 0
Hardware Path: 0/10/0/0
Station Address (hex): xxxxxxx
Card Type: [ 1000Base-T ->]
Speed : [ 1000 ->]
Duplex Mode: [ FULL ->]
Autoneg: [ ON ->]
Internet Address: 199.99.99.59 [ Modify Host Name Aliases.. ]
Subnet Mask: 255.255.254.0 (optional)


10/100 CARD:
==============================================
Card Name: lan0
IP Interface #: 0
Hardware Path: 0/0/0/0
Station Address (hex): xxxxxxxx
Card Type: [ Fast Ether ->]
Autoneg: [ OFF ->]
Speed (million bps): [ 100 ->]
Duplex Mode: [ FULL ->]
Internet Address: 199.99.99.60 [ Add Host Name Aliases.. ]
Subnet Mask: 255.255.254.0 (optional)

++++++++++++++++++++++++++++++++++++++++++++

So the IP addresses are different (they have always been), but both have the same Subnet, I guess it will be best to disable for now the slowest card until I can replace the IP/subnet of the slowest card (given Sanjay and Melvyn comments regarding conflicts using the same subnet).

The scenario I encountered was that for a long time packets sent were using only the Gigacard, however recently (I do not know the reason) the delivery switched momentarily to the slowest card until I did the reset yesterday, then it went back to delivering packets with the fastest of the two cards again.

[Gerhard Roets]

They are on the same subnet ... like John said it causes erratic results. Meaning it might work at times(even for a long time) and at other times it wont work at all.

The basic thing is the machines bases its IP decisions on the cards network and station address. But with two cards in the same subnet(even if they have different IP's) that will cause problems.

Regards
Gerhard

[rick jones]

Indeed, assigning two separate NICs IP addresses in the same subnet is not a good idea with HP-UX. While both will receive traffic, only one will be used for outbound traffic. If the two NICs are not then connected to the same switches/routers (that is, that the switches are not meshed together) one can have "issues" with connectivity.

One can force replies to go out the interface on which they entered by setting ip_strong_es_model to a value of 1. This will also mean that traffic for IP A will not be accepted on NIC B and vice versa.

One might also setup a bunch of host/network routes pointing at each interface IP as apropriate.

Finally though, if what you really want is some sort of fail-over, the best thing to do is to get and install the Auto Port Aggregation (APA) software and configure the two NICs under the LAN Monitor functionality.