Route-based VPN between Juniper and Cisco

crypto isakmp policy 1
 encr aes 256
 authentication pre-share
 group 5

crypto isakmp invalid-spi-recovery
crypto isakmp keepalive 10
crypto isakmp key 0 keyforlab123 address 2.2.2.2

crypto ipsec transform-set ESP_AES_256 esp-aes 256 esp-sha-hmac

crypto ipsec profile CIPHER-AES-256
 set transform-set ESP_AES_256

interface Tunnel18
 description tunnel_to_srx
 ip address 192.168.100.1 255.255.255.252
 tunnel source GigabitEthernet0/0
 tunnel destination 2.2.2.2
 tunnel mode ipsec ipv4
 tunnel protection ipsec profile CIPHER-AES-256
end

interfaces {
    st0 {
        unit 0 {
            family inet {
                mtu 1514;
                address 192.168.100.2/30;

security {
    ike {
        proposal p1-aes {
            authentication-method pre-shared-keys;
            dh-group group5;
            authentication-algorithm sha1;
            encryption-algorithm aes-256-cbc;
        }
        policy ike-policy-1 {
            mode main;
            proposals p1-aes;
            pre-shared-key ascii-text "keyforlab123"
        }
        gateway cisco {
            ike-policy ike-policy-1;
            address 1.1.1.1;
            dead-peer-detection;
            external-interface fe-0/0/0;
        }
    }
    ipsec {
        proposal ipsec-proposal-1 {
            protocol esp;
            authentication-algorithm hmac-sha1-96;
            encryption-algorithm aes-256-cbc;
        }
        policy ipsec-policy-1 {
            perfect-forward-secrecy {
                keys group5;
            }
            proposals ipsec-proposal-1;
        }
        vpn vpn-to-cisco {
            bind-interface st0.0;
            ike {
                gateway cisco;
                ipsec-policy ipsec-policy-1;
            }
            establish-tunnels immediately;
        }
    }
}