[c-nsp] Nexus 7k MSDP issue

Wed Jun 20 12:06:53 EDT 2012

Just a follow up for anyone who googles this.  From Cisco:

The problem here is that TCP 3-way handshake is taking more time than expected. In NX-OS MSDP implementation, after triggering 3-way handshake(by calling connect()), we wait for 1ms for it to complete. If the handshake is not complete, we try the same operation in loop for 5 times. Even after 5 such iterations if handshake is not complete, we retry after msdp reconnect interval. 

Issue has been fixed as part of "CSCtw53967    N7k-reg: MSDP peers failed to established due to TCP read Error" by increasing wait-time to 50ms and loop count to 50.
Fixed in 6.1(1)S, 6.0(2)S25 and 5.2(4)S

The bug is not externally visible.

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of James Slepicka (c-nsp)
Sent: Thursday, June 07, 2012 9:02 AM
To: cisco-nsp (cisco-nsp at puck.nether.net)
Subject: [c-nsp] Nexus 7k MSDP issue

I'm having trouble establishing an MSDP session between a 7k running 6.0(1) and a 4900M running 12.2(53)SG2.  When the 7k (1.1.1.1) attempts to connect to the 4900M (2.2.2.2), it immediately resets the connection.  Some info and ethanalyzer output is below.  I have a TAC case open but we haven't made much progress, so I'm just reaching out to see if anyone has run into this before.

Thanks,
James

7k# sh ip msdp sum
MSDP Peer Status Summary for VRF "default"
Local ASN: 65000, originator-id: 1.1.1.1

Number of configured peers:  1
Number of established peers: 0
Number of shutdown peers:    0

Peer            Peer        Connection      Uptime/   Last msg  (S,G)s
Address         ASN         State           Downtime  Received  Received
2.2.2.2         0           Inactive        00:02:52  never     0

7k# sh ip msdp event-history tcp

 tcp events for MSDP process
2012 May  2 07:15:53.337376 msdp [11883]: : msdp_connect_main(): EXIT, tid 0xb11a6b90
2012 May  2 07:15:53.337006 msdp [11883]: : msdp_open_peer() connect() 2.2.2.2 default Operation already in progress
2012 May  2 07:15:53.335934 msdp [11883]: : connect() returned Operation already in progress
2012 May  2 07:15:53.334701 msdp [11883]: : connect() returned Operation already in progress
2012 May  2 07:15:53.333471 msdp [11883]: : connect() returned Operation already in progress
2012 May  2 07:15:53.332239 msdp [11883]: : connect() returned Operation already in progress
2012 May  2 07:15:53.330996 msdp [11883]: : connect() returned Operation now in progress
2012 May  2 07:15:53.329597 msdp [11883]: : msdp_connect_main(): open peer, tid 0xb11a6b90
2012 May  2 07:15:53.329230 msdp [11883]: : Socket is setup, sid: 43, peer address 2.2.2.2
2012 May  2 07:15:53.328126 msdp [11883]: : msdp_connect_main(): Start Connect thread, tid 0xb11a6b90
2012 May  2 07:15:53.327696 msdp [11883]: : Opened connection with peer 2.2.2.2
2012 May  2 07:15:53.327692 msdp [11883]: : Started thread, We are connect (active) side of connection, using local address 1.1.1.1
2012 May  2 07:15:53.327456 msdp [11883]: : We are connect (active) side of connection, using local address 1.1.1.1
2012 May  2 07:15:53.327449 msdp [11883]: : Retry opening connection with peer 2.2.2.2

No.     Time                       Source             Destination      Protocol Info
      1 2012-05-16 15:17:36.872947 1.1.1.1            2.2.2.2          TCP      46602 > msdp [SYN] Seq=0 Win=16384 Len=0 MSS=536 WS=1 TSval=33148882 TSecr=0
      2 2012-05-16 15:17:36.891431 2.2.2.2            1.1.1.1          TCP      msdp > 46602 [SYN, ACK] Seq=0 Ack=1 Win=16384 Len=0 MSS=536
      3 2012-05-16 15:17:36.891602 1.1.1.1            2.2.2.2          TCP      46602 > msdp [RST] Seq=1 Win=0 Len=0
      4 2012-05-16 15:17:46.892898 1.1.1.1            2.2.2.2          TCP      46825 > msdp [SYN] Seq=0 Win=16384 Len=0 MSS=536 WS=1 TSval=33148977 TSecr=0
      5 2012-05-16 15:17:46.911616 2.2.2.2            1.1.1.1          TCP      msdp > 46825 [SYN, ACK] Seq=0 Ack=1 Win=16384 Len=0 MSS=536
      6 2012-05-16 15:17:46.911827 1.1.1.1            2.2.2.2          TCP      46825 > msdp [RST] Seq=1 Win=0 Len=0

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