Why is in OSPF LSA sequence nuber in range 0x80000001 to 0x7FFFFFFF

Question

Why is in OSPF LSA sequence number in range 0x80000001 to 0x7FFFFFFF. I suppose that it is for some historical reasons but cannot google it.

score 2 · Accepted Answer · edited Oct 07 '21 at 06:06

2

LSA sequence number is a signed 32-bit integer.

So 0x80000001 to 0x7fffffff basically covers the whole possible range except one number: 0x80000000, and this special number is reserved.

You can read this page of RFC 2328 for more details.

edited Oct 07 '21 at 06:06

Community

answered Feb 23 '13 at 23:30

zzk

score 1 · Answer 2 · answered Jun 02 '14 at 16:07

1

As a signed integer, the sequence number counts from -2 147 483 647 to 2 147 483 647.

If it would count from 0x00000001 to 0xffffffff, it would appear as a count from 1 to 2 147 483 647 and then from -2 147 483 648 to -1.

answered Jun 02 '14 at 16:07

Wasp

2 Answers2