[c-nsp] Replacement for HSRP

[Bulgaria Online - Assen Totin]

	Hi all,

I have a pretty weird situation and I'm trying to figure out a
work-around for it. 

We have 2 Cisco 2821 each equipped with a 16-port switch (Service
Module). Both act as gateways to a local network - each LAN device is
connected to both Service Modules (bonding interface) and one of the two
Gi ports of the each router are connected to one and same ISP. 

The Service Modules utilize HSRP to provide all LAN devices with a
default gateway address. 

However, the ISP blocks multicast packets on our external interfaces, so
the routers cannot talk to each other, hence HSRP is not actually
running - both external interfaces claim to be master because no slave
can be reached. (The ISP is in Japan and it is difficult to understand
why they do so; they have not been very co-operative.)

Since the Service Modules are separate entities running their own IOS,
the router has no way of tracking the status of the internal interface. 

My last resort may be to connect the two routers to each other using the
available Gi ports on each chassis, then somehow monitor this link (if
one of the devices goes down, the link will go down; this is much worse
than HSRP, but is still better than nothing) and enable/disable the ISP
interface, depending on the status of this link (or may be just bring up
and down a secondary IP address). Basically, this means the ability to
enable/disable one Ethernet interface depending on the link status of
another Ethernet interface. 

Any ideas how to achieve this (if possible at all) are welcome - up to
writing a TCL job to run in the router... 

Thanks in advance,

Assen Totin