On 25 Feb 2016, at 13:41, Benoit Claise <bcla...@cisco.com> wrote:
Dear all,
Sorry for the delay (mix of vacation and business travel).
Let me try to summarize the situation as I see it:
- From the routing RFCs, BGP Identifier, OSPF router ID, TE identifier, and LSR
identifiers are all an unsigned integers.
- We need consistency for the router ID and identifier in YANG leaf/typedef
- The OSPF MIB module has defined
RouterID ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"A OSPF Router Identifier.
Note that the Router ID, in OSPF, has the same format
as an IP address, but identifies the router independent
of its IP address."
SYNTAX IpAddress
ospfRouterId OBJECT-TYPE
SYNTAX RouterID
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"A 32-bit integer uniquely identifying the
router in the Autonomous System.
By convention, to ensure uniqueness, this
should default to the value of one of the
router's IP interface addresses.
As Adrian mentioned: it is NOT an IP address but the MIB module uses the
notational formatting of n IP address for display purposes.
- An IPv4 address as OSPF router ID doesn't make sense in an IPv6 environment
Based on this, I believe that:
- We must not associate an IP address semantic with the router ID
- Based on Brian's feedback (which I agree with) "As long as the YANG module does
not specify a format that makes the routerID display like an IPv4 address", it was
probably a mistake to have defined RouterID as IpAdress in OSPF MIB module.
- Interestingly, https://tools.ietf.org/html/draft-ietf-netmod-routing-cfg-20
contains:
grouping router-id {
description
"This grouping provides router ID.";
leaf router-id {
type yang:dotted-quad;
description
"A 32-bit number in the form of a dotted quad that is used by
some routing protocols identifying a router.";
reference
"
RFC 2328
: OSPF Version 2.";
}
}
This should be an uint32 number.
- An union-based solution is a bad compromise
From draft-raza-mpls-ldp-mldp-yang-02
leaf lsr-id {
type union {
type yang:dotted-quad;
type uint32;
}
description "LSR ID.";
Since the question was asked: as AD, I would support uint32 everywhere.
Now, practically, how to move forward?
- Either all drafts reference draft-ietf-netmod-routing-cfg-20 (with the uint32
modification),
- Or you create a "Common Routing YANG Data Types", similarly to RFC 6991
including the router IDs. I see already many typedef in draft-raza-mpls-ldp-mldp-yang-02
- Or you define you own types in your own draft
But, if we have agreement on the uint32, let's document this now
somewhere/somehow, and let's not revisit this on regular basis (yes, I see it
coming...)
A few lines of explanation in the draft would already help for example, in an
operational section, explaining to people the mapping of the MIB OSPF RouterID
to the YANG object
Regards, Benoit
Hi Adrian,
On 2/16/16 7:53 AM, Adrian Farrel wrote:
Hi Brian,
I said I wasn't going to participate in this discussion :-)
Nice try. ;)
I should not respond to questions that I don't fully understand, but:
the BGP Identifier is an unsigned integer
the OSPF router ID is an unsigned integer
I assume the above is based on the YANG definition of OSPF routerID. RFC
4750 says the routerID is an IPv4 address. Is that an issue?
To quote from 4750...
RouterID ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"A OSPF Router Identifier.
Note that the Router ID, in OSPF, has the same format
as an IP address, but identifies the router independent
of its IP address."
SYNTAX IpAddress
So it explicitly says it is NOT an IP address but the MIB module uses the
notational formatting of n IP address for display purposes.
I think this is done because the router ID is often chosen to be an IP address
of the router, and because it is easier for humans to deal with a.b.c.d where
each element is a 3-digit number less than 256, than it is to manage a single
number in the range 0 to 2^32 -1.
The above is the textual convention, whereas the following is the actual
OSPF routerID...
ospfRouterId OBJECT-TYPE
SYNTAX RouterID
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"A 32-bit integer uniquely identifying the
router in the Autonomous System.
By convention, to ensure uniqueness, this
should default to the value of one of the
router's IP interface addresses.
So the MIB actually says the default is to use an IPv4 address...
All that being said, my point was further along where I said:
I am not concerned with what the operator will choose as his/her
routerID value. I am concerned with what format options will be
associated with the routerID in the yang module. As long as the format
options does not allow display in dotted decimal notation, I am fine.
As long as the YANG module does not specify a format that makes the
routerID display like an IPv4 address, I am fine.
Brian
