Document ID: 17648
Contents
Introduction
Prerequisites
Requirements
Affected Products
Affected Versions
More Information
Related Information
Introduction
When you use a subnet mask of 255.255.255.248 (four hosts) on a network that starts with network number 232, you cannot reach a host numbered 235 on the network attached to the router when you route through the router.
Prerequisites
Requirements
There are no specific requirements for this document.
Affected Products
1200i, 1220i, 1250i, 1270i, 2600i, 2900i, 2200R, 2220R, 2250R, 2270R, 3500R, 3800R, VSR-2, and VSR-8
Affected Versions
Versions later than 5.0 but earlier than 5.1
More Information
The specific problem is where the router is an Ethernet to WAN router, the WAN is a numbered Frame Relay link and the Ethernet port is numbered at x.x.x.233. Nodes numbered at 234, 236 on the Ethernet can be reached across the Frame Relay link. However, the node numbered at 235 cannot be reached through the router.
The default network broadcast is the problem.
For example, with the networks of:
WAN 198.14.9.64 255.255.255.252 LAN 198.14.9.80 255.255.255.240
The call to netmask() matches the WAN network when trying to set the default network broadcast for the LAN network. The invalid combination of the mask of 255.255.255.252 with the network of 198.41.9.80 has led to a 198.41.9.83 being added to the broadcast table.
Before the fix:
2270R>show ip broadcast ========================== IP Broadcast Table Entries -------------------------- 198.41.11.207 198.41.11.255 198.41.11.192 198.41.9.95 198.41.9.80 198.41.9.64 198.41.9.83 <---- The cause of the problem 198.41.9.67 198.41.9.0 198.41.12.0 198.41.9.255 198.41.11.0 198.41.12.255
After the fix:
2270R>show ip broadcast ========================== IP Broadcast Table Entries -------------------------- 198.41.11.207 198.41.11.255 198.41.11.192 198.41.9.95 198.41.9.80 198.41.9.64 198.41.9.67 198.41.9.0 198.41.12.0 198.41.9.255 198.41.11.0 198.41.12.255
Related Information
| Updated: May 03, 2004 | Document ID: 17648 |