Ignore Router-Id In Best-Path Calculation; Four-Byte As Numbers; As4 Number Representation - Dell S4048–ON Configuration Manual

Ignore Router-ID in Best-Path Calculation

You can avoid unnecessary BGP best-path transitions between external paths under certain conditions. The bgp bestpath
router-id ignore command reduces network disruption caused by routing and forwarding plane changes and allows for faster
convergence.

Four-Byte AS Numbers

You can use the 4-Byte (32-bit) format when configuring autonomous system numbers (ASNs).
The 4-Byte support is advertised as a new BGP capability (4-BYTE-AS) in the OPEN message. If a 4-Byte BGP speaker has sent
and received this capability from another speaker, all the messages will be 4-octet. The behavior of a 4-Byte BGP speaker is different
with the peer depending on whether the peer is a 4-Byte or 2-Byte BGP speaker.
Where the 2-Byte format is 1-65535, the 4-Byte format is 1-4294967295. Enter AS numbers using the traditional format. If the ASN
is greater than 65535, the dot format is shown when using the show ip bgp commands. For example, an ASN entered as
3183856184 appears in the show commands as 48581.51768; an ASN of 65123 is shown as 65123. To calculate the comparable dot
format for an ASN from a traditional format, use ASN/65536. ASN%65536.
Traditional DOT Format
Format
65001 0.65501
65536 1.0
100000 1.34464
4294967295 65535.65535
When creating Confederations, all the routers in a Confederation must be either 4-Byte or 2-Byte identified routers. You cannot mix
them.
Configure 4-byte AS numbers with the four-octet-support command.

AS4 Number Representation

Dell Networking OS supports multiple representations of 4-byte AS numbers: asplain, asdot+, and asdot.
NOTE: The ASDOT and ASDOT+ representations are supported only with the 4-Byte AS numbers feature. If 4-Byte AS
numbers are not implemented, only ASPLAIN representation is supported.
ASPLAIN is the default method the system uses. With the ASPLAIN notation, a 32-bit binary AS number is translated into a decimal
value.
• All AS numbers between 0 and 65535 are represented as a decimal number when entered in the CLI and when displayed in the
show commands output.
• AS numbers larger than 65535 are represented using ASPLAIN notation. When entered in the CLI and when displayed in the
show commands output, 65546 is represented as 65546.
ASDOT+ representation splits the full binary 4-byte AS number into two words of 16 bits separated by a decimal point (.): <high-
order 16 bit value>.<low-order 16 bit value>. Some examples are shown in the following table.
• All AS numbers between 0 and 65535 are represented as a decimal number, when entered in the CLI and when displayed in the
show commands outputs.
• AS Numbers larger than 65535 is represented using ASDOT notation as <higher 2 bytes in decimal>.<lower 2 bytes in decimal>.
For example: AS 65546 is represented as 1.10.
ASDOT representation combines the ASPLAIN and ASDOT+ representations. AS numbers less than 65536 appear in integer format
(asplain); AS numbers equal to or greater than 65536 appear in the decimal format (asdot+). For example, the AS number 65526
appears as 65526 and the AS number 65546 appears as 1.10.
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Border Gateway Protocol IPv4 (BGPv4)