Issue:
BGP packets got bounced on Netscaler. Customer has configured BGP on the Netscaler. Customer has reported that, in the nstrace, he could see the BGP packet coming from the peer switch was not accepted by the Netscaler.

-Issue was resolved by rebuilding the VPX, the BGP session has become stable and no BGP packets got bounced on NetScaler. Also issue was observed on this specific VPX instance of SDX and other VPX instance where the BGP was working fine. Please note that this is a secondary Netscaler with INC.

A permanent solution to this problem is by configuring the "constant router id". Configure the constant router id for the system so that router id updates are not triggered:

C48_DUT1#conf t C48_DUT1(config)#router-id 10.236.255.57 C48_DUT1(config)#end

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Problem Cause

 
It is observed from the newnslogs that the LA/1 interface is flapping. Since LA/1 is bound to VLAN 128,when LA/1 goes down VLAN 128 also goes down. 
This triggers the automatic router id selection process and this results in the BGP session is being reset. The reason for LA channel flap is below.

The VPX which had the issue is 10.236.25.73_13. When checked in xenstore_info.out [/var/shell in collector] the LA channel configuration is not found. If LA channel is configured from SVM, it will be seen in the Xenstore_info output. This value is fetched from XenServer at the time the collector was captured. If LA channel is added from VPX, it is not observed in the XenStore_info. Hence it is assumed that the LA channel was added/created at the VPX level. 

On observing the VPX which was working in 10.236.25.45, it can be seen that the LA channel configuration in Xenstore_info.out. 

Logs: 

[jobinb@sjanalysis-1 /upload/ftp/70327476/collector_S_10.236.25.73_13Jul2015_10_31/shell]$ more xenstore_info.out vmname_mac_table = "{'cdl128-bda01ma-wius':['3a:20:0b:66:4b:0b','ca:9b:0d:5d\..." 
interface = "" 
mtu = "[10/1:1500,10/2:1500]" 
L2mode = "0" 
dedicated = "0" 
gateway = "10.236.25.1" 
ip = "10.236.25.73" 
netmask = "255.255.255.0" 
nsvlan_id = "0" 
nsvlan_intflist = "" 
nsvlan_tagged = "0" 
physical_intflist = "" 
priv = "b84ac6745ffa4cd4819c19a3a0b9f022" 
priv2 = "ce8299aad9866985ac44c430119d528854a60381941eafaabf57e2e4e437ca36eb6\..." 
pw = "1cb5e4e3103eee2d53c282ef0ef677de3841a6f25610d5247" 
vlan_id = "0" 

Priv2 = ce8299aad9866985ac44c430119d528854a60381941eafaabf57e2e4e437ca36eb69890905d912e0c57134fb4e40844c2366c56c25daff722646e505c220ebb7 

Mac_interface_list = 8e_85_a3_63_f0_15-0/1,ee_82_8a_8a_ed_f5-0/2,3a_20_0b_66_4b_0b-10/1,ca_9b_0d_5d_29_1e-10/2 


[jobinb@sjanalysis-1 /upload/ftp/70327476/collector_S_10.236.25.45_11Aug2015_01_44/shell]$ more xenstore_info.out | more vmname_mac_table = "{'cdl100-bda01ma-wius':['42:f7:5c:c3:ca:80','9a:2e:09:9a\..." 
interface = "" 
mtu = "[10/1:1500,10/2:1500,LA/1:1500]" 
L2mode = "0" 
dedicated = "0" 
gateway = "10.236.25.1" 
ip = "10.236.25.45" 
netmask = "255.255.255.0" 
nsvlan_id = "0" 
nsvlan_intflist = "" 
nsvlan_tagged = "0" 
physical_intflist = "" 
priv = "7831c14f1eba5d6550ccaee1e7ff2659" 
priv2 = "a6b0193917bc48f68f165c69408db2a611780aa76f1005de5ae5bbd571fdb319b44\..." 
pw = "157bec273b3ceb5cad5a442d070864fd2306c616af58bc09c" 
vlan_id = "0" 
LA = "" 
1 = "" 
interface_list = "10/1,10/2" 
mac = "00_e0_ed_44_9e_69" 
type = "LACP" 

Priv2 = a6b0193917bc48f68f165c69408db2a611780aa76f1005de5ae5bbd571fdb319b448e37d1d570dc49f8f2ab17336632d507727fdcc5673a504d569fa32f9aa77 

Mac_interface_list = 72_01_22_66_6b_ae-0/1,ea_80_88_b2_65_73-0/2,42_f7_5c_c3_ca_80-10/1,9a_2e_09_9a_ac_94-10/2