<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Thank you Jörg for the quick update.<div><br></div><div>Yes, I had a few messages with Mikrotik regarding this issue, and they keep saying that the devices are old, and almost I agree with them because I cannot duplicate the issue using Quagga/FRR/Bird and Cisco IOS/XR BGP. That is why I am asking the experts.<div><br></div><div>Mikrotik said this in their last reply:</div><div><br></div><div>"<span style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;">As it was mentioned before, RouterOS sends ASes encoded in 4bytes even if ASN fit in 2bytes because RFC states</span></div><p style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;">"</p><p style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;">" A BGP speaker that advertises such a capability to a particular peer, and receives from that peer the advertisement of such a capability, MUST encode AS numbers as four-octet entities in both the AS_PATH attribute and the AGGREGATOR attribute in the updates it sends to the peer and MUST assume that these attributes in the updates received from the peer encode AS numbers as four-octet entities. "</p><p style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;">"</p><p style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;"> </p><p style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;">No matter you like it or not, that old software on remote peers are not RFC compliant, there were other customers who complained about the same problem, upgrade of this old software fixes the problem.</p><p style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;"> </p><p style="caret-color: rgb(23, 43, 77); color: rgb(23, 43, 77); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif; font-size: 14px;"> We will not make hacks just to support software from 2007 that are not current RFC compliant."<br></p><div><br></div><div><br><div><br><blockquote type="cite"><div>On 29 Jun 2023, at 15:31, Jörg Kost <jk@ip-clear.de> wrote:</div><br class="Apple-interchange-newline"><div><div>Hello Bogdan,<br><br>According to https://www.rfc-editor.org/rfc/rfc4271.html,<br><br>"the AGGREGATOR is an attribute of length 6", not 8.<br><br>According to https://www.rfc-editor.org/rfc/rfc6793.html,<br><br>"the AS4_AGGREGATOR attribute in an UPDATE message SHALL be considered malformed if the attribute length is not 8".<br><br>I think it looks like a bug in the Mikrotik BGP code that tries to encode AS4 in an AS attribute.<br><br>BR<br>Jörg<br><br><br>On 29 Jun 2023, at 13:44, Bogdan-Stefan Rotariu wrote:<br><br><blockquote type="cite">Hi there,<br><br>We have some CER2024 in our network, and we are starting to encounter issues when receiving prefixes from Mikrotik CCR2216 that is running with ROSv7. Has anyone any ideea except replacing the CER’s?<br><br>The peer is has AS4 capability negociated:<br><br> Neighbor AS4 Capability Negotiation:<br> Peer Negotiated AS4 capability<br> Peer configured for AS4 capability<br><br>We are running version 6.3.0.fT183:<br><br>IronWare : Version 6.3.0fT183 Copyright (c) 2017-2019 Extreme Networks, Inc.<br>Compiled on Jul 14 2022 at 21:38:40 labeled as ce06300f<br>(18589108 bytes) from Primary<br><br>last-packet-with-error decode shows :<br><br>Received Message Length: 94<br>BGP Message:<br> 0xffffffff 0xffffffff 0xffffffff 0xffffffff 0x005e0200<br> 0x00004340 0x01010050 0x02001602 0x05000022 0x04000015<br> 0xe60000ad 0x820000ad 0x820000ad 0x82400304 0x0a0b010f<br> 0x40050400 0x00006440 0x0600d008 0x00042204 0x0064d007<br> 0x00080000 0xad825509 0x1f8617c3 0xd204<br><br>BGP Header<br> Marker: 0xffffffff 0xffffffff 0xffffffff 0xffffffff<br> Message Length: (0x005e) 94<br> Message Type: (0x02) UPDATE<br><br>UPDATE Message<br>Unfeasible route length: (0x0000) 0<br>Update path attributes<br>Total Path Attribute length: (0x0043) 67<br> Flags : (0x40) Well Known, Transitive, Complete<br> Type : (0x01) Origin<br> Length: (0x01) 1<br> Origin: (0x00) IGP<br><br> Flags : (0x50) Well Known, Transitive, Complete, Extended length<br> Type : (0x02) AS Path<br> Length: (0x0016) 22<br> Segment Type : (0x02) AS Sequence<br> Segment Length: (0x05) 5<br> AS Numbers : (0x0000) 0, (0x2204) 8708, (0x0000) 0, (0x15e6) 5606, (0x0000) 0,<br> Segment Type : (0xad) Unknown(173)<br> Segment Length: (0x82) 130<br> AS Numbers : (0x0000) 0, (0xad82) 44418, (0x0000) 0, (0xad82) 44418,<br><br> Flags : (0x40) Well Known, Transitive, Complete<br> Type : (0x03) Next Hop<br> Length: (0x04) 4<br> Next Hop IP address: (0x0a0b010f) 10.11.1.15<br><br> Flags : (0x40) Well Known, Transitive, Complete<br> Type : (0x05) Local Preference<br> Length: (0x04) 4<br> Local Preference: (0x00000064) 100<br><br> Flags : (0x40) Well Known, Transitive, Complete<br> Type : (0x06) Atomic Aggregate<br> Length: (0x00) 0<br><br> Flags : (0xd0) Optional, Transitive, Complete, Extended length<br> Type : (0x08) Community<br> Length: (0x0004) 4<br> Community List: (0x22040064) 8708:100<br><br> Flags : (0xd0) Optional, Transitive, Complete, Extended length<br> Type : (0x07) Aggregator<br> Length: (0x0008) 8<br>Error: Invalid AGGREGATOR attribute length 8<br>_______________________________________________<br>foundry-nsp mailing list<br>foundry-nsp@puck.nether.net<br>http://puck.nether.net/mailman/listinfo/foundry-nsp<br></blockquote></div></div></blockquote></div><br></div></div></body></html>