ospf: T9606: document "compatible rfc1583" and "compatible rfc7474"T9606-ospf-compatible

The RFC1583 option moved from "parameters rfc1583-compatibility" to
"compatible rfc1583". Its entry now uses the new path and notes the
automatic migration.

The new "compatible rfc7474" option enables strict sequence number
validation for cryptographic authentication. Without it, packets with
equal sequence numbers are also accepted, as needed for interoperability
with e.g. Cisco NX-OS.

1 files changed, 25 insertions, 13 deletions

diff --git a/docs/configuration/protocols/ospf.md b/docs/configuration/protocols/ospf.md
index b3297b3d..767624a3 100644
--- a/docs/configuration/protocols/ospf.md
+++ b/docs/configuration/protocols/ospf.md
@@ -64,6 +64,31 @@ with the same router-ID!
 
 #### Optional
 
+```{cfgcmd} set protocols ospf compatible rfc1583
+
+{rfc}`2328`, the successor to {rfc}`1583`, suggests according to section
+G.2 (changes) in section 16.4.1 a change to the path preference algorithm
+that prevents possible routing loops that were possible in the old version
+of OSPFv2. More specifically it demands that inter-area paths and
+intra-area backbone path are now of equal preference but still both
+preferred to external paths.
+
+This command should NOT be set normally.
+```
+
+
+```{cfgcmd} set protocols ospf compatible rfc7474
+
+Enable strict {rfc}`7474` sequence number validation for OSPFv2
+cryptographic authentication (MD5 and HMAC-SHA). Received packets must
+then have a strictly increasing sequence number.
+
+When this option is not set, packets with equal sequence numbers are also
+accepted. This is required for interoperability with implementations that
+may reuse sequence numbers, such as Cisco NX-OS.
+```
+
+
 ```{cfgcmd} set protocols ospf default-information originate [always] [metric \<number\>] [metric-type \<1|2\>] [route-map \<name\>]
 
 Originate an AS-External (type-5) LSA describing a default route into all
@@ -142,19 +167,6 @@ see ospf-shortcut-abr-02.txt
 ```
 
 
-```{cfgcmd} set protocols ospf parameters rfc1583-compatibility
-
-{rfc}`2328`, the successor to {rfc}`1583`, suggests according to section
-G.2 (changes) in section 16.4.1 a change to the path preference algorithm
-that prevents possible routing loops that were possible in the old version
-of OSPFv2. More specifically it demands that inter-area paths and
-intra-area backbone path are now of equal preference but still both
-preferred to external paths.
-
-This command should NOT be set normally.
-```
-
-
 ```{cfgcmd} set protocols ospf interface \<interface\> passive [disable]
 
 This command specifies interface as passive. Passive interface advertises