Some sites become unavailable

[klumpen]

Hi,

Have a big problem with my EX switches (3 EX4200 in VC).

Sometimes sites become unavailable. A lot of customers have complained the last weeks that some sites suddently gets slow (in the browers it says "waiting for www.site.com". 

They can open a new tab, write in the exact new site, and it startes to load immediately (waiting for... in the other tab)

I'm running 9.5R1.8, but will try to upgrade to 9.5R2.7 to monday. 

Have anyone experience with problems like this before?

Had problems like this in earlier junos releases, but this disappeared after upgrading to 9.5R1.8. It seems that it is back know.

Anyone any clue what this can be? 

[firewall72]

Hi,

Based on what you wrote, you may have an underlying connectivity or DNS issue.  I would first rule out issues at L1/2 and work your way up from them.  Try the following:

1. Identify the switch ports your test machine and dns server are plugged into
2. Check the interfaces for errors (i.e. show interfaces xxxx detail) 
3. Run a persistent ping (ping x.x.x.x -t) to the DNS server and one other resource on the same switch
4. Run a "nslookup domain.com" to a test destination using a browser on the test machine
5. Does the nslookup resolve an IP?  Any errors?  Dropped packets?
6. If needed, check the trunks, VLAN's (show interfaces vlan terse" and "show ethernet-switching interfaces)\

I hope this helps.

-John

[klumpen]

My network is splitted into two parts.

Have a "layer 2" network and a MPLS network. Both is terminated in a layer3 switch (hp procurve 6200yl).

Topologi:

Inet transitt 

       |

ISG 2000 adv (transparent)

       |

Hp 6200yl

  |          |

MPLS   Juniper VC

The problem is only in the "Juniper VC network", not the MPLS net.  They both share the same transit connection, dns servers, dhcp e.g.

Can not see any problem on the trunk to the gepon or link to our cmts. Both is behind the Juniper switch, and both have problems. 

Customers have reported that the problem only conserns web-traffic. Gaming, email e.g works without problem.

[firewall72]

Hi,

Based on your response, I don't think you're having connectivity issues.  However, I would recommend testing connectivity and name resolution from a problematic machine.  Where does your DNS server sit?  What you explained in your first post is leaning me towards DNS.  I would try nslookups to 10 domains and record the results.  If you get a some errors or time-outs, I would clear the cache and then run some tests to the internet using a web browser.  Feel free to report findings.

-John