Declaration of alternate route in static configuration

[a8965]

Configuration : L1000 in HPUX 11.00

For a dedicated subnet, I'd like to configure 2 different static routes (through 2 different routers : routerA & routerB / redundancy of routers).

routerA is used for primary route (first declaration in routing table).

Ex : netstat -rn
destination Gateway Flags Interface
10.8.5.0 routerA UG lan0
10.8.5.0 routerB UG lan0

If routerA fails, what will happen?
Will the traffic be automatically processed by routerB as declared in routing table or will the server continue to try to proceed through routerA ??

In fact, I'd like to know if the route switching is automatic when 2 routes are declared for a same subnet and when the primary route goes down

[Ravi_8]

Hi, Olivier

In /etc/rc.config.d/netconf file
ROUTE_DESTINATION[0]="default"
ROUTE_MASK[0]=""
ROUTE_GATEWAY[0]="x.x.x.x"
ROUTE_COUNT[0]="1"
ROUTE_ARGS[0]=""

For each additional route, add a set of variable assignments like the above
changing the index to"[0]", "[1]".
and you have to start the gated daemon.
In the same file change the GATED flag to 1

GATED=1

and stop/start the network

#/sbin/init.d/nettl stop
#/sbin/init.d/net stop
#/sbin/init.d/net.init stop

and start in the reverse way.

[benoit Bruckert]

Olivier,
the failed gateway is using a round robin algorithm in HP-UX, this means that if router 1 failed, then It will used router B.
But when router A is back, your system will not use it , it will continue to use router B unless this one is failing. In fact, after a failure of one router, and this one is back, the system will used any one of them.
If the cost of the route between each router, you can define 2 statics routes. If you want to define a priority, then the only way is to used gated on the server, and rip,ospf, or any other routing method....
On my side, with the same kind of trouble, I defined on each router, a rip server, with 2 differents costs for the route ! In order to control exactly which router is the main !

hth
Benoit

[rick jones]

Going the gated route may be a bit of overkill here.

The description of how UX will switch from one route to the other sounds good - I'd add that one probably needs to have the dead gateway detection enabled for it to work (but I'm not certain). That is on by default, and assumes that the router(s) will respond to ICMP echo requests (pings) from the host.

Depending on the capabilities of the routers, you might also simply point the 10.8.5.0 route at the IP address for lan0 and give it a metric of 0 - this will then rely on the two routers supporting ProxyARP, and the existing ARP cache mechanaisms/ndd settings would come into play. In theory the two routers would decide who would reply, even if not, if one were down, it wouldn't reply to the ARP requests from the host for hosts in the 10.8.5.0 network and only the other could :)