Incredible Adventures of the OSPF Huawei

We found SUDDENLY that OPSF with hello-timer=1 on the Huawei NE40E got convergency more then 20 seconds. And any changing of timers is not helped. We have schemes with such timer value, the reason is some old equipment without BFD. And everything worked fine 1-2 month ago. Official Huawei TAC respond — For mitigation OSPF … Continue reading »

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Mirroring of untagged ports in Extreme\Huawei switches

I faced with task of mirroring few untagged ports from Extreme and Huawei switches to one monitoring server. It is trivial task, but I found some interesting issue.

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Problem with CIsco WLC and AIR-AP1231G

Recently I met problem with old Cisco AP (model AIR-AP1231G). The problem was in the connection between WLC and AP. The procedure with new LWAPP\CAPWAP AP look like this: – AP with factory ios for autonomy work try to find WLC when loading; – if AP did not find WLC, it stays to live like … Continue reading »

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Cisco SSH Denial of Service Vulnerability

If you used Cisco router as border or vpn concentrator (that is somebody has access to it from Internet), you would update software near time. Remote attacker could exploit this vulnerability by attempting a reverse SSH login with a crafted username

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BGPlay and BGPviz

If you have AS and more then one upstream you can meet strange traffics behavior sometimes. Suddenly you can see that biggest part of you traffic goes from one upstream or familiar pattern of traffics distribution has changed. It happens cause something changes, far away from you and your provider . Maybe one big provider … Continue reading »

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The small cisco digest

– Cisco announces the end-of-sale and end-of life dates for the very popular old models of Cisco Catalyst – 3750G, 3560G, 3750-E, and 3560-E Series. You have 1 year for buy it. And five years for fix it 😉 ( – Cisco announces the new corporate Wi-Fi Access Point “Cisco Aironet 3600”. “Clean Air”, 802.11r … Continue reading »

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Trouble with PoE with linecard WS-X4648-RJ45V+E

There was issue with linecard WS-X4648-RJ45V+E in the 4510 chassis. Without any records in the logs new PoE devices that were attached to the switch on linecard didn`t work (switch did not provide power for them). Furthermore, we turned off\on old device (that still working on this moment) and it did not work too. From … Continue reading »

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F5 3600 BIG-IP LTM redundancy

I recently tested this balancers (two – cause redundancy). I liked these devices, especially for iRules functionality. But I strongly disappointed about his realisation of redundancy (Active-Standby). If we want to determine what device from redundancy couple should be active, after reboot this “active” device redundancy scheme don’t work correctly. From tests with traffic dump … Continue reading »

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Simple advise

Do not configure both redundant links on the switch simultaneously 🙁

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Simple IP SLA jitter test

There is simple way to test your channel on jitter with ip sla in Cisco IOS. This test is ideal for testing Internet-connection in the back-office or something like that. If you need check jitter in the voice channel or some tcp-ip server-client connections, you need more complicated decision.

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