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Some PPPOE subscriber cannot access Internet even pass authentication after reset the service board

Publication Date:  2014-12-16 Views:  92 Downloads:  0
Issue Description

【 ProblemSu mm ary 】 ME60 Slot 5 has memory alarm , after changing the board, some PPPoE subscriber authentication successfully , but cannot open the web page.
【 ProblemDetails 】 after changing the issue board, some PPPoE subscriber authentication successfully , but cannot open the webpage.

Handling Process

1 check the CPU and the alarm, there is no abnormal state;

2 suspect that may ME60 ACL filter TCP 80 port, there is no ACL port filter after checking on the device;

3 suspect that may has QOS limit, there is no QOS limit on device;

4 suspect the board or card has hardware issue, changing the board and card, issue still happen. not the board issue.

5 after the subscriber obtain the address, ping DNS ok, ping Baidu address ok , but cann't open web pages;

6 Capture packet at the terminal end. found there is many TCP retransmission information (picture: terminal send a large amount of retransmission message).

7 Check the configuration, one command : portal - server redirect-limit 5 . This command is configured for When the Subscriber passed the authentication, it need to redirect 5 times before is can access the internet;

8 Check the board protocol packet statistics, a large number of portal packet discarding ;

 [XX-XX-ME60-B1-diagnose]display cpu-defend statistics-all slot 5
CarID Index Packet-Info Passed-Packets Dropped-Packets
--------------------------------------------------------------------------------
8 15 PES_EXCP_CAUSE_ARP 1 0
49 181 PES_EXCP_CAUSE_DIPBC 306488 0
50 51 PES_EXCP_CAUSE_IPOPT 31 0
51 182 PES_EXCP_CAUSE_DIP224 683461 0
59 39 PES_EXCP_CAUSE_TTLERR 2949991 2893
61 184 PES_EXCP_CAUSE_V4TNLEND 2773 0
139 193 PES_EXCP_CAUSE_OTHER_PRCL 2 0
151 200 PES_EXCP_CAUSE_PSF 3621637 0
214 223 PES_EXCP_CAUSE_TEST_PKT 1322502 0
218 9 PES_EXCP_CAUSE_NEW_RIP 6 0
231 19 PES_EXCP_CAUSE_NEW_NTP 18729 0
234 22 PES_EXCP_CAUSE_NEW_LSP_PING 2 0
237 23 PES_EXCP_CAUSE_NEW_IGMP 1 0
239 12 PES_EXCP_CAUSE_NEW_ICMP 6399574 0
242 48 PES_EXCP_CAUSE_NEW_TCPSYN 378323 0
243 17 PES_EXCP_CAUSE_NEW_DHCP 55315 0
249 241 PES_EXCP_CAUSE_NEW_TCPSYN_TELNET 3 0
288 238 PES_EXCP_ID_WLAN_WAP 1 0
301 270 PES_EXCP_ID_QVCT_MISS_ARP 9405230 268966
316 228 PES_EXCP_ID_MSE_IPARP_TRIGGER 555393 0
333 1134 EXCP_ID_PADI 10638799 863901
363 253 PES_EXCP_ID_PPPOE_CTRL 45145234 45766
364 254 PES_EXCP_ID_PPPOE_IGMP 214103 0
366 230 PES_EXCP_ID_PPPOE_PORTAL 8936980 168426418 // a huge discarding
367 268 PES_EXCP_ID_PPPOE_ECHO 181288138 0
368 225 PES_EXCP_ID_HOST_CAR_TO_CP 2155 67
370 259 PES_EXCP_ID_DHCP_V6PKT 199343 0
371 260 PES_EXCP_ID_IPOE_V6_LINK_LOCAL_PKT 2 0
373 262 PES_EXCP_ID_IPOE_ICMP_V6_MC_PKT 214367 0
378 266 PES_EXCP_ID_BRAS_IPV4_DHCP 505633 0
390 1103 EXCP_ID_PADR 8793657 309262
--------------------------------------------------------------------------------

9 ME60 board  Portal Car is 512K by default, modify  to 800K ,issue is fixed.

Root Cause

ME60 equipment board Portal Car is 512K by default. When a large number of subscriber ( 9000 user) get online at the same time, there will be a huge PPPOE PORTAL discarding, this  is the root cause of the issue.

HTTP request packet is small, why there is so many discarding? Through analysis (picture: redirection packet) we can see, HTTP use the TCP protocol, TCP must complete three handshake before it transfer data. even one packet discard, TCP retransmission occurs, this negotiation end, and it will begin next TCP negotiation.

Solution

【 ResolutionSu mm ary 】 After the portal car is modified problem solved

【 ResolutionDetails 】

Configure cpu-defend

#

Cpu - defendpolicy 1
car portal cir 800

#

In the user access card delivery

   Slot 5
  cpu - defend policy 1

The board portal car from the default 512K, is changed to 800K.

Suggestions

The configuration requirements need to redirect five times, that is the subscriber pass the authentication, open a web page by browser, it can access the internet after 5 times redirection . once there is Portal Car discarding, it will lead to retransmission, subscriber cannot access the Internet. Though this issue is fixed by modifying Portal Car, this issue will also happen if a large amount subscriber get online at the same time. Therefore, we suggest config as this :  After the subscriber pass the authentication, if the subscriber access the Internet by browser in 3 seconds, there will be redirection.   if the subscriber access the Internet by browser after 3 seconds, there is no need redirection. The configuration in Domain view: portal-redirect redirect-time 3

END