Expand Networks has updated its WAN acceleration software, solving what it claims is a common industry problem, but has immediately been accused of spreading fear, uncertainty and doubt.

The company claims the addition of its router transparency mode (RTM) means it is the only WAN optimiser that does not conflict with network monitoring software or with established network capabilities such as Cisco QoS and ACLs. This is because it compresses only the payload and not the packet headers.

"An acceleration box affects the packet headers," says Pedro Colaco, Expand's marketing VP. "We preserve the packet markers, as do our competitors, but an MPLS router also wants to look at the header, for example to see the destination server, while ACLs on a router look at the source and destination IPs for security.

"But by compressing, the Expand device changes those and breaks the ability to use the header parameters - we believe this is our biggest obstacle. Performance is critical, but so is transparency - it's no good if it breaks Netflow or NetScout."

However, another WAN acceleration vendor accused Expand of hyping up a problem that doesn't exist. "They're spreading FUD around header preservation," says Steve Wastie, Peribit's international marketing manager. "Can we maintain header data when we compress? Yes we can - it's a relatively minor feature. I don't know why they're focusing on it."

He adds that Peribit already has customers using its devices with Cisco networks and on MPLS: "Some users turn header preservation on, most don't. It's not an issue."