Bad Peer AS with 4B AS issue

[Łukasz Jarosz]

I highly doubt that, but their NOC is not exactly helpful on the matter.

They say that peer is configured for my ASN, but as I said router is out of my control.
Nothing else, just Bad peer AS. I hope screenshot was not cut, but in case tshark dump below:
BIRD initiation:
Border Gateway Protocol - OPEN Message
Marker: ffffffffffffffffffffffffffffffff
Length: 51
Type: OPEN Message (1)
Version: 4
My AS: 23456 (AS_TRANS)
Hold Time: 240
BGP Identifier: [redacted]
Optional Parameters Length: 22
Optional Parameters
Optional Parameter: Capability
Parameter Type: Capability (2)
Parameter Length: 20
Capability: Multiprotocol extensions capability
Type: Multiprotocol extensions capability (1)
Length: 4
AFI: IPv4 (1)
Reserved: 00
SAFI: Unicast (1)
Capability: Route refresh capability
Type: Route refresh capability (2)
Length: 0
Capability: Graceful Restart capability
Type: Graceful Restart capability (64)
Length: 2
[Expert Info (Chat/Request): Graceful Restart Capability supported in Helper mode only]
[Graceful Restart Capability supported in Helper mode only]
[Severity level: Chat]
[Group: Request]
Restart Timers: 0x0078
0... .... .... .... = Restart state: No
.0.. .... .... .... = Graceful notification: No
.... 0000 0111 1000 = Time: 120
Capability: Support for 4-octet AS number capability
Type: Support for 4-octet AS number capability (65)
Length: 4
AS Number: [redacted 6-digits]
Capability: Enhanced route refresh capability
Type: Enhanced route refresh capability (70)
Length: 0

PEER response:
Border Gateway Protocol - OPEN Message
Marker: ffffffffffffffffffffffffffffffff
Length: 63
Type: OPEN Message (1)
Version: 4
My AS: [redacted 4 digits]
Hold Time: 90
BGP Identifier: [redacted]
Optional Parameters Length: 34
Optional Parameters
Optional Parameter: Capability
Parameter Type: Capability (2)
Parameter Length: 6
Capability: Multiprotocol extensions capability
Type: Multiprotocol extensions capability (1)
Length: 4
AFI: IPv4 (1)
Reserved: 00
SAFI: Unicast (1)
Optional Parameter: Capability
Parameter Type: Capability (2)
Parameter Length: 2
Capability: Route refresh capability (Cisco)
Type: Route refresh capability (Cisco) (128)
Length: 0
Optional Parameter: Capability
Parameter Type: Capability (2)
Parameter Length: 2
Capability: Route refresh capability
Type: Route refresh capability (2)
Length: 0
Optional Parameter: Capability
Parameter Type: Capability (2)
Parameter Length: 4
Capability: Graceful Restart capability
Type: Graceful Restart capability (64)
Length: 2
[Expert Info (Chat/Request): Graceful Restart Capability supported in Helper mode only]
[Graceful Restart Capability supported in Helper mode only]
[Severity level: Chat]
[Group: Request]
Restart Timers: 0x4078, Graceful notification
0... .... .... .... = Restart state: No
.1.. .... .... .... = Graceful notification: Yes
.... 0000 0111 1000 = Time: 120
Optional Parameter: Capability
Parameter Type: Capability (2)
Parameter Length: 6
Capability: Support for 4-octet AS number capability
Type: Support for 4-octet AS number capability (65)
Length: 4
AS Number: [redacted 4 digits]
Optional Parameter: Capability
Parameter Type: Capability (2)
Parameter Length: 2
Capability: Long-Lived Graceful Restart (LLGR) Capability
Type: Long-Lived Graceful Restart (LLGR) Capability (71)
Length: 0
Border Gateway Protocol - NOTIFICATION Message
Marker: ffffffffffffffffffffffffffffffff
Length: 21
Type: NOTIFICATION Message (3)
Major error Code: OPEN Message Error (2)
Minor error Code (Open Message): Bad Peer AS (2)

Best regards,
Łukasz Jarosz
On cze 14 2023, at 2:40 pm, Ondrej Zajicek <santiago at crfreenet.org> wrote:
> On Wed, Jun 14, 2023 at 12:20:37PM +0200, Łukasz Jarosz wrote:
> > I think worth mentioning is that I have 4B AS whilst my peer has 2B AS.
> > All I get is this error:
> >
> > I checked pcap dumps and they seem reasonable. BIRD open is followed by peer OPEN with piggybacked NOTIFICATION message.
> >
> > Based on MAC address my peer is Juniper, but that is just my guess.
>
> It is possible that the peer is so old that it does not support 4B ASN extension?
> Or isn't the peer just misconfigured, expecting different ASN?
> In logs, aren't there some value in 'Bad peer AS' message after
> colon (like 'Bad peer AS: XYZ')?
>
> --
> Elen sila lumenn' omentielvo
>
> Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
> OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
> "To err is human -- to blame it on a computer is even more so."
>

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