Riverbed SteelHead 5080, Руководство по установке и настройке

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Troubleshooting | 53
Asymmetric routing
Asymmetric routing
If there’s an asymmetric routing issue, many connections fail during data transfer or they fail to start.
Possible cause
Asymmetric routing occurs when a TCP connection takes one path to the destination and another when
returning to the source. If the SteelHead sees only the LAN-to-WAN or only the WAN-to-LAN packets,
it can’t optimize the data.
Solutions
To resolve the asymmetric routing issue, do one of the following:
• Rank these options from most to least preferable with respect to complexity and cost, and then
select an option:
– configure a fixed-target rule.
– use a logical in-path configuration such as WCCP or PBR.
– use four-port or six-port SteelHead.
– configure connection-forwarding with two SteelHeads.
• Remove the asymmetry.
Packet ricochet
These symptoms occur due to packet ricochet:
• Performance is less than expected.
• A log message similar to this appears:
kernel:[intercept.NOTICE] nat_check: SYN packet for already natted connection a.a.a.a:xxxx ->
b.b.b.b:yyyy ==> a.a.a.a:xxxx -> c.c.c.c:7801
where:
a.a.a.a is the client IP address
xxxx is the source port
b.b.b.b is the server IP address
yyyy is the destination port
c.c.c.c:7801 is the local SteelHead in-path IP address
Possible cause
Traffic to the LAN is traveling to the WAN router on the way to the LAN.
Solutions
To resolve packet ricochet issues:
• Change the in-path gateway to the LAN router.