Colin,
You are correct that the way to define a memorable IPv6 address with stateless autoconfiguration is to define your own interface ID.
Stateless autoconfiguration is mutually exclusive with defining your own IP addresses, so you cannot define an additional IP address on an autoconfigured IPv6 interface. Well you can, but that will turn off autoconfiguration. Here is the reference, from the IPv6 Network and Application Design Guide: Stateless autoconfiguration is supported for an OSA-Express® QDIO interface in z/OS® Communications Server if no manually configured addresses are defined on the interface. Also: A stateless autoconfigured address is deleted when its valid lifetime expires or when a manually defined address is added to the interface.
There is more information in that section you might find useful.
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Mike Fox
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Original Message:
Sent: Tue April 09, 2024 08:36 AM
From: Colin Paice
Subject: Configuring static routes, is there a reason why defaultx is different ?
Hi Mike,
Thanks for your reply, I've a follow on question about Stateless configuration.
I had to configure radvd on Linux for it to work.
If I defined an IP address on my z/OS definitions, it ignored the prefix from RADVD and the advertisements (this is documented)
It gave me an IP address with a mangled MAC address.
If I want a nice short memorable IP address such as 2001:4::6, . I could do it if I had
INTERFACE JFPORTCP6
DEFINE IPAQENET6
CHPIDTYPE OSD
PORTNAME PORTC
PRIROUTER
INTFID 0:0:0:6
Is there a better way?
So to get this to work, I need to
- configure radvd to have prefix 2001:4::/64,
- specify the intfid on the z/OS interface
- remove any manually configured IP addresses
Is this correct?
If so, how do I give the interface a second IP address, such as 2001:4::17
regards
Colin
Do you have any thoughts on this?
Original Message:
Sent: 3/28/2024 3:34:00 PM
From: Mike Fox
Subject: RE: Configuring static routes, is there a reason why defaultx is different ?
A static default route needs a next hop address configured because the purpose of a default route to tell the host what router to forward packets to, when it doesn't have a more specific route to the destination. The next hop address identifies that router.
IPv6 supports stateless address configuration. With that function you don't have to configure these static routes, instead when z/OS comes up it will send a broadcast router solicitation message asking who is the router on this LAN. The router will respond with a router advertisement telling z/OS the prefix of the LAN (which would get your prefix route automatically added to the routing table) and the router's link local address (which would get the correct default route with the correct link local address automatically added to the routing table). This is the preferred way to implement IPv6 and is illustrated in the attached screenshot.
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Mike Fox
Original Message:
Sent: Mon February 12, 2024 05:06 AM
From: Colin Paice
Subject: Configuring static routes, is there a reason why defaultx is different ?
I can configure a static route
ROUTE 2001:db8:1::/64 = JFPORTCP6 MTU 5000
and a default route
ROUTE default6 2001:db8:3::3 JFPORTCP6 MTU 1492
With the default route I have to explicitly configure 2001:db8:3::3 at the remote end to match.
With the '=' I do not have to explicitly code 2001:db8:3::3 - it seems to take the randomly generated address (eg fe80::50d9:7aff:fe37:9679) which changes every time I restart.
Is there a technical reason why default6 ( and default) need the explicit address?
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Colin Paice
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