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Troubleshooting Guide

CloudEngine 16800, 12800, 12800E, 8800, 7800, 6800, and 5800 Series Switches

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Web Pages Are Partially Displayed When a CE12800 Functions as the Gateway for Web Page Access

Web Pages Are Partially Displayed When a CE12800 Functions as the Gateway for Web Page Access

Keywords

Gateway, web page, CE12800, switch

Abstract

Web pages are partially displayed when a CE12800 functions as the gateway for web page access.

Problem Description

Figure 14-13 Network topology

Two CE12800s set up a CSS to function as a Layer 3 gateway, connect to an S9300, and have links of two carriers (carrier A and carrier B). The CE12800s have routes configured, among which default routes point to carrier A's network device. The CE12800s import servers' Internet access traffic to the link connected with carrier B's network device through 300 specific routes. The S9300 is a carrier's device, connects to the CE12800s through Layer 3 interfaces, and does not run IGPs such as OSPF.

Fault Symptom

After routes are configured on the CE12800s, the PC that is connected to the CE12800s and uses an IP address on the same network segment as carrier B's network device accesses web pages through carrier B's link at a very low speed. Additionally, the PC cannot open many web pages but can access some services, such as QQ chat application.

Procedure

After this fault occurs in commissioning, external network access is tested and proven to be normal when only default routes are configured. This indicates that external network access through carrier A's link is normal.

After specific routes destined for carrier B's network device are configured, the fault occurs. The PC is then connected to the S9300 to test whether its external network access is normal. The results show that its external network access is normal, indicating that the S9300 is working properly. When the PC is connected to the CE12800s, the fault occurs. The outbound interface of the default routes is then changed to the outbound interface of carrier B's network device, and the PC can access external networks normally. When the outbound interface of the default routes is the outbound interface of carrier A's network device, some external network access traffic forwarded by carrier B's network device may be transmitted to carrier A's network device instead of being forwarded along specific routes and so is interrupted.

Packet headers are obtained for further analysis. Baidu website access is used as an example for a test. Obtained packet header information shows that the Baidu website's address returned by the DNS service of carrier B does not match carrier B's specific routes.

Solution

Considering that carriers assign a fixed public network IP address to users, use PBR to redirect all the traffic with the source IP address as carrier B's fixed public network IP address to carrier B's link and configure default routes to point to carrier A's network device. Additionally, configure lower-priority default routes to point to carrier B' network device to ensure uplink backup.

The configuration details are as follows:

[~HUAWEI] acl number 3006
[*HUAWEI-acl4-advance-3006] description LianTongDiZhi
[*HUAWEI-acl4-advance-3006] rule 5 permit ip source XX.XX.XX.0 0.0.0.127 //Carrier B's public network address assigned to the customer
[*HUAWEI-acl4-advance-3006] quit
[*HUAWEI] commit
[~HUAWEI] traffic classifier liantong type or
[*HUAWEI-classifier-liantong] if-match acl 3006
[*HUAWEI-classifier-liantong] quit
[*HUAWEI] commit
[~HUAWEI] traffic behavior liantong
[*HUAWEI-behavior-liantong] redirect nexthop XX.XX.XX.XX  //The next hop is the IP address of carrier B's public network outbound interface
[*HUAWEI-behavior-liantong] quit
[*HUAWEI] commit
[~HUAWEI] traffic policy liantong
[*HUAWEI-trafficpolicy-liantong] classifier liantong behavior liantong precedence 5
[*HUAWEI-trafficpolicy-liantong] quit
[*HUAWEI] commit
[~HUAWEI] ip route-static 0.0.0.0 0.0.0.0 XX.XX.XX.XX preference 80 //Carrier B's link is the backup of carrier A's link
[*HUAWEI] ip route-static 0.0.0.0 0.0.0.0 XX.XX.XX.XX  //Carrier A's link
[*HUAWEI] commit

When web page access faults occur, locate the fault on different access points and then obtain packet headers to determine whether route selection is correct. If the destination IP address will change in carrier network access, use PBR to change route selection results based on the fixed source IP address and consider link backup.

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Updated: 2020-01-07

Document ID: EDOC1000060766

Views: 610266

Downloads: 2956

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