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Cisco Bug: CSCvs63891 - APIC CallHome Mail Data Line Termination Incorrect not Respecting SMTP RFC 5321

Last Modified

May 12, 2020

Products (1)

  • Cisco Application Policy Infrastructure Controller (APIC)

Known Affected Releases

4.0(3d)

Description (partial)

Symptom:
-	Issue is some emails sent to the CallHome dest grp SMTP Server from the APICs arent arriving at the email recipient
-	Emails sent from the switches are arriving without any issues at the SMTP Server and email recipients
-	ACI Fabric is running fw rel 4.0(3d) with a Microsoft based SMTP Server
-	The CallHome Dest format is set for RFC compliant and short-txt format
-	Tcpdump on the APICs and SMTP Server shows SMTP packets being exchanged fine
-	The APIC2 tcpdump show correct SMTP Request params/codes and data fragments being exchanged between APIC 
        and SMTP Server
-	HOWEVER, the issue is observed towards the end of the data fragments after the end of the mail body is sent ending 
        o	The SMTP client should indicate the end-of-message by sending the following ASCII character sequence -> ?<CR><LF>.<CR><LF>? as per RFC 5321
        o	There are special ASCII chars which are a Carriage Return (CR) followed a LineFeed (LF) a dot char followed by another CR and LF again

-	The ?<CRLF>.<CRLF>? is not observed in the short-txt end of the mail body
        o	Instead we observe the following ?<LF>.<CR><LF>?
        o	See example below from the APIC tcpdump written to pcap and opened in WireShark

        	Simple Mail Transfer Protocol
        	    Line-based text data (3 lines)
        	        Created: 1574869726189\n
                        <snip>
        	        Severity: info.\r\n

        o	As shown there is only an <LF> before the dot char and <CR><LF> after the dot character. The initial <CR> is missing

-	After this the APIC sends an SMTP QUIT command which respects the SMTP RFCs, but then the SMTP Server sends a message with SMTP Response Code 451 Response Param 4.7.0

        	From the same APIC pcap
        	Simple Mail Transfer Protocol
        	    Response: 451 4.7.0 Timeout waiting for client input\r\n
        	        Response code: Requested action aborted: local error in processing (451)
        	        Response parameter: 4.7.0 Timeout waiting for client input

-	This is then followed by a FIN, ACK from the APIC and a subsequent ACK from the SMTP Server

Conditions:
-	ACI Fabric running fw rel 4.0(3d) with a Microsoft based SMTP Server
-	The CallHome Dest format is set for RFC compliant and short-txt format
-       Is an issue only on mails generated from the APICs themselves
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