You are browsing a read-only backup copy of Wikitech. The live site can be found at wikitech.wikimedia.org
LVS and Varnish
LVS and Varnish infrastructure
"upload" and "mobile" traffic operate similarly to "text" shown here.
Within the caching layer (cpxxx machines), the jump from nginx to varnish:80 is direct on the local host only.
However, the jump from varnish:80 (frontend) to varnish:3128 (backend) is different: for that jump, we hash on the URL (etc) when balancing to the backends to divide the cache space among all machines, and thus the request typically moves from one machine to another within the cache layer here.