ppp0 is v.34 -> hostA
ppp1 is isdn -> hostB

default route -> hostB
ip addresses are a subset from hostA so the loop for packets from 
machines other than the gateway is:

	  ---> ISDN -> hostB --> NET
[machine]
	  <--- v.34 <- hostA <-- NET

unfortunately this sometimes leads to terrible loops where the
ISDN TD light is solid on and the v.34 RD is solid on.  Mbuf use
shoots up and everything locks down.  It seems to be ftp from a 
mac on the local net that locks everything like this.  Ideas?
Packets look like this:

20:20:19.598423 millschick.abattoir.com.ssh > gabriella.abattoir.com.1023: . ack 1 win 16500 <nop,nop,timestamp 3327422 205333> (DF) [tos 0x10]
20:20:19.635673 millschick.abattoir.com.ssh > gabriella.abattoir.com.1023: . ack 1 win 16500 <nop,nop,timestamp 3327422 205333> (DF) [tos 0x10]
20:20:19.787415 millschick.abattoir.com.ssh > gabriella.abattoir.com.1023: . ack 1 win 16500 <nop,nop,timestamp 3327422 205333> (DF) [tos 0x10]
20:20:19.817846 millschick.abattoir.com.ssh > gabriella.abattoir.com.1023: . ack 1 win 16500 <nop,nop,timestamp 3327422 205333> (DF) [tos 0x10]
20:20:20.000642 millschick.abattoir.com.ssh > gabriella.abattoir.com.1023: . ack 1 win 16500 <nop,nop,timestamp 3327423 205333> (DF) [tos 0x10]